WEBVTT Kind: captions Language: en 00:00:16.039 --> 00:00:23.359 align:start position:0% hi<00:00:18.830> hi<00:00:19.830> my<00:00:20.100> name's<00:00:20.279> Dominic<00:00:20.580> once<00:00:20.910> I<00:00:22.369> founder 00:00:23.359 --> 00:00:23.369 align:start position:0% hi hi my name's Dominic once I founder 00:00:23.369 --> 00:00:25.099 align:start position:0% hi hi my name's Dominic once I founder of<00:00:23.490> just<00:00:24.090> a<00:00:24.180> research<00:00:24.480> project<00:00:24.750> called 00:00:25.099 --> 00:00:25.109 align:start position:0% of just a research project called 00:00:25.109 --> 00:00:27.490 align:start position:0% of just a research project called affinity<00:00:25.529> which<00:00:26.060> seeks<00:00:27.060> to<00:00:27.210> advance 00:00:27.490 --> 00:00:27.500 align:start position:0% affinity which seeks to advance 00:00:27.500 --> 00:00:30.200 align:start position:0% affinity which seeks to advance blockchain<00:00:28.500> technology<00:00:28.970> with<00:00:29.970> a<00:00:30.000> particular 00:00:30.200 --> 00:00:30.210 align:start position:0% blockchain technology with a particular 00:00:30.210 --> 00:00:34.160 align:start position:0% blockchain technology with a particular focus<00:00:30.449> on<00:00:30.869> scalability<00:00:32.120> in<00:00:33.120> the<00:00:33.780> process<00:00:34.079> of 00:00:34.160 --> 00:00:34.170 align:start position:0% focus on scalability in the process of 00:00:34.170 --> 00:00:35.920 align:start position:0% focus on scalability in the process of doing<00:00:34.320> that<00:00:34.440> we<00:00:34.649> look<00:00:34.800> at<00:00:34.920> many<00:00:35.160> different 00:00:35.920 --> 00:00:35.930 align:start position:0% doing that we look at many different 00:00:35.930 --> 00:00:39.229 align:start position:0% doing that we look at many different types<00:00:36.930> of<00:00:37.170> distributed<00:00:37.829> algorithm<00:00:38.760> and<00:00:39.000> in 00:00:39.229 --> 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position:0% space we often spend a lot of time talking<00:00:47.190> about<00:00:47.629> block<00:00:48.629> chains<00:00:48.989> and<00:00:49.440> block 00:00:49.610 --> 00:00:49.620 align:start position:0% talking about block chains and block 00:00:49.620 --> 00:00:55.459 align:start position:0% talking about block chains and block chain<00:00:49.860> like<00:00:50.100> consensus<00:00:52.460> systems<00:00:53.460> and<00:00:54.469> think 00:00:55.459 --> 00:00:55.469 align:start position:0% chain like consensus systems and think 00:00:55.469 --> 00:00:57.229 align:start position:0% chain like consensus systems and think the<00:00:55.829> purpose<00:00:56.309> of<00:00:56.340> my<00:00:56.430> talk<00:00:56.640> is<00:00:56.670> to<00:00:57.030> introduce 00:00:57.229 --> 00:00:57.239 align:start position:0% the purpose of my talk is to introduce 00:00:57.239 --> 00:00:59.810 align:start position:0% the purpose of my talk is to introduce another<00:00:58.079> form<00:00:58.410> of<00:00:58.469> consensus<00:00:58.859> which<00:00:59.579> has<00:00:59.699> been 00:00:59.810 --> 00:00:59.820 align:start position:0% another form of consensus which has been 00:00:59.820 --> 00:01:04.219 align:start position:0% another form of consensus which has been around<00:01:00.000> for<00:01:00.329> longer<00:01:01.010> Luna's<00:01:02.989> byzantium<00:01:03.989> fault 00:01:04.219 --> 00:01:04.229 align:start position:0% around for longer Luna's byzantium fault 00:01:04.229 --> 00:01:06.289 align:start position:0% around for longer Luna's byzantium fault tolerant<00:01:04.589> consensus<00:01:05.129> which<00:01:05.820> is<00:01:05.970> based<00:01:06.150> on 00:01:06.289 --> 00:01:06.299 align:start position:0% tolerant consensus which is based on 00:01:06.299 --> 00:01:10.070 align:start position:0% tolerant consensus which is based on message<00:01:06.630> passing<00:01:08.659> so<00:01:09.659> I'm<00:01:09.720> going<00:01:09.869> to<00:01:09.900> try<00:01:10.049> and 00:01:10.070 --> 00:01:10.080 align:start position:0% message passing so I'm going to try and 00:01:10.080 --> 00:01:12.200 align:start position:0% message passing so I'm going to try and do<00:01:10.290> this<00:01:10.470> in<00:01:10.680> 20<00:01:11.100> minutes<00:01:11.250> which<00:01:11.520> is<00:01:11.700> kind<00:01:12.180> of 00:01:12.200 --> 00:01:12.210 align:start position:0% do this in 20 minutes which is kind of 00:01:12.210 --> 00:01:14.450 align:start position:0% do this in 20 minutes which is kind of challenging<00:01:12.720> but<00:01:12.990> I<00:01:13.229> want<00:01:13.740> to<00:01:13.770> just<00:01:13.979> give<00:01:14.280> it<00:01:14.400> a 00:01:14.450 --> 00:01:14.460 align:start position:0% challenging but I want to just give it a 00:01:14.460 --> 00:01:16.370 align:start position:0% challenging but I want to just give it a give<00:01:15.090> you<00:01:15.180> a<00:01:15.210> fear<00:01:15.509> of<00:01:15.540> some<00:01:15.840> of<00:01:15.960> the<00:01:16.080> issues 00:01:16.370 --> 00:01:16.380 align:start position:0% give you a fear of some of the issues 00:01:16.380 --> 00:01:18.289 align:start position:0% give you a fear of some of the issues involved<00:01:16.830> and<00:01:17.220> what<00:01:17.850> these<00:01:17.970> kind<00:01:18.240> of 00:01:18.289 --> 00:01:18.299 align:start position:0% involved and what these kind of 00:01:18.299 --> 00:01:22.490 align:start position:0% involved and what these kind of consensus<00:01:18.990> protocols<00:01:19.680> look<00:01:19.860> like<00:01:20.540> so<00:01:21.540> first 00:01:22.490 --> 00:01:22.500 align:start position:0% consensus protocols look like so first 00:01:22.500 --> 00:01:24.530 align:start position:0% consensus protocols look like so first of<00:01:22.619> all<00:01:22.710> quickly<00:01:23.640> it's<00:01:23.820> worth<00:01:23.970> just<00:01:24.210> asking 00:01:24.530 --> 00:01:24.540 align:start position:0% of all quickly it's worth just asking 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and the answer is they're<00:01:34.110> useful<00:01:34.380> for<00:01:34.860> creating<00:01:35.240> scale-out 00:01:36.230 --> 00:01:36.240 align:start position:0% they're useful for creating scale-out 00:01:36.240 --> 00:01:39.789 align:start position:0% they're useful for creating scale-out crips<00:01:36.780> alleges<00:01:37.200> that's<00:01:37.470> crypt<00:01:38.159> alleges<00:01:38.490> that 00:01:39.789 --> 00:01:39.799 align:start position:0% crips alleges that's crypt alleges that 00:01:39.799 --> 00:01:42.410 align:start position:0% crips alleges that's crypt alleges that increase<00:01:40.799> their<00:01:41.009> transaction<00:01:41.610> throughput<00:01:42.210> as 00:01:42.410 --> 00:01:42.420 align:start position:0% increase their transaction throughput as 00:01:42.420 --> 00:01:47.510 align:start position:0% increase their transaction throughput as more<00:01:43.549> nodes<00:01:44.549> join<00:01:44.970> the<00:01:45.119> network<00:01:45.680> so<00:01:46.680> you<00:01:47.399> know 00:01:47.510 --> 00:01:47.520 align:start position:0% more nodes join the network so you know 00:01:47.520 --> 00:01:49.219 align:start position:0% more nodes join the network so you know the<00:01:47.640> objective<00:01:48.329> of<00:01:48.390> the<00:01:48.509> research<00:01:48.810> effort<00:01:49.110> is 00:01:49.219 --> 00:01:49.229 align:start position:0% the objective of the research effort is 00:01:49.229 --> 00:01:51.260 align:start position:0% the objective of the research effort is to<00:01:49.259> transport<00:01:49.890> the<00:01:50.159> creation<00:01:50.610> of<00:01:50.700> sort<00:01:51.210> of 00:01:51.260 --> 00:01:51.270 align:start position:0% to transport the creation of sort of 00:01:51.270 --> 00:01:54.859 align:start position:0% to transport the creation of sort of limitless<00:01:51.600> to<00:01:52.170> centralize<00:01:52.590> clouds<00:01:53.420> that<00:01:54.420> can 00:01:54.859 --> 00:01:54.869 align:start position:0% limitless to centralize clouds that can 00:01:54.869 --> 00:01:57.020 align:start position:0% limitless to centralize clouds that can be<00:01:54.990> used<00:01:55.229> in<00:01:55.560> the<00:01:56.340> case<00:01:56.490> of<00:01:56.520> an<00:01:56.729> open 00:01:57.020 --> 00:01:57.030 align:start position:0% be used in the case of an open 00:01:57.030 --> 00:01:59.749 align:start position:0% be used in the case of an open decentralized<00:01:58.100> virtual<00:01:59.100> machine<00:01:59.399> like 00:01:59.749 --> 00:01:59.759 align:start position:0% decentralized virtual machine like 00:01:59.759 --> 00:02:02.469 align:start position:0% decentralized virtual machine like etherium<00:02:00.210> to<00:02:00.509> run<00:02:00.869> you<00:02:01.049> know<00:02:01.170> gmail<00:02:01.710> goober 00:02:02.469 --> 00:02:02.479 align:start position:0% etherium to run you know gmail goober 00:02:02.479 --> 00:02:05.469 align:start position:0% etherium to run you know gmail goober Facebook<00:02:03.479> Twitter<00:02:03.750> that<00:02:04.049> kind<00:02:04.290> of<00:02:04.350> thing 00:02:05.469 --> 00:02:05.479 align:start position:0% Facebook Twitter that kind of thing 00:02:05.479 --> 00:02:07.760 align:start position:0% Facebook Twitter that kind of thing internet<00:02:06.479> of<00:02:06.570> things 00:02:07.760 --> 00:02:07.770 align:start position:0% internet of things 00:02:07.770 --> 00:02:10.890 align:start position:0% internet of things services<00:02:08.770> layer<00:02:08.950> and<00:02:09.070> so<00:02:09.280> on<00:02:09.340> and<00:02:09.600> the<00:02:10.600> most<00:02:10.780> of 00:02:10.890 --> 00:02:10.900 align:start position:0% services layer and so on and the most of 00:02:10.900 --> 00:02:11.910 align:start position:0% services layer and so on and the most of the<00:02:10.960> three<00:02:11.140> different<00:02:11.470> kinds<00:02:11.620> of 00:02:11.910 --> 00:02:11.920 align:start position:0% the three different kinds of 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decentralized<00:02:20.260> systems<00:02:20.680> as<00:02:21.340> of<00:02:21.760> the<00:02:22.240> type 00:02:22.500 --> 00:02:22.510 align:start position:0% decentralized systems as of the type 00:02:22.510 --> 00:02:24.240 align:start position:0% decentralized systems as of the type that<00:02:22.780> banks<00:02:23.140> are<00:02:23.260> currently<00:02:23.560> creating<00:02:23.800> for 00:02:24.240 --> 00:02:24.250 align:start position:0% that banks are currently creating for 00:02:24.250 --> 00:02:27.290 align:start position:0% that banks are currently creating for settlement<00:02:24.790> of<00:02:24.850> clearing<00:02:25.150> and<00:02:25.390> also<00:02:26.320> think 00:02:27.290 --> 00:02:27.300 align:start position:0% settlement of clearing and also think 00:02:27.300 --> 00:02:29.730 align:start position:0% settlement of clearing and also think actually<00:02:28.300> the<00:02:28.570> centralization<00:02:29.380> is<00:02:29.470> a 00:02:29.730 --> 00:02:29.740 align:start position:0% actually the centralization is a 00:02:29.740 --> 00:02:31.140 align:start position:0% actually the centralization is a completely<00:02:30.130> new<00:02:30.250> computing<00:02:30.640> paradigm<00:02:30.820> and 00:02:31.140 --> 00:02:31.150 align:start position:0% completely new computing paradigm and 00:02:31.150 --> 00:02:33.030 align:start position:0% completely new computing paradigm and we're<00:02:31.300> going<00:02:31.420> to<00:02:31.450> see<00:02:31.660> it<00:02:31.860> within<00:02:32.860> the 00:02:33.030 --> 00:02:33.040 align:start position:0% we're going to see it within the 00:02:33.040 --> 00:02:35.970 align:start position:0% we're going to see it within the enterprise<00:02:33.240> so<00:02:34.240> people<00:02:35.230> are<00:02:35.440> going<00:02:35.530> to<00:02:35.650> create 00:02:35.970 --> 00:02:35.980 align:start position:0% enterprise so people are going to create 00:02:35.980 --> 00:02:39.150 align:start position:0% enterprise so people are going to create to<00:02:36.580> centralize<00:02:36.970> databases<00:02:37.570> which<00:02:38.160> highly 00:02:39.150 --> 00:02:39.160 align:start position:0% to centralize databases which highly 00:02:39.160 --> 00:02:40.890 align:start position:0% to centralize databases which highly fault<00:02:39.400> tolerant<00:02:39.790> because<00:02:39.910> you<00:02:40.660> know<00:02:40.720> that's 00:02:40.890 --> 00:02:40.900 align:start position:0% fault tolerant because you know that's 00:02:40.900 --> 00:02:43.380 align:start position:0% fault tolerant because you know that's where<00:02:41.110> the<00:02:41.170> design<00:02:41.440> they<00:02:41.940> easy<00:02:42.940> to<00:02:43.060> administer 00:02:43.380 --> 00:02:43.390 align:start position:0% where the design they easy to administer 00:02:43.390 --> 00:02:45.900 align:start position:0% where the design they easy to administer because<00:02:43.990> they're<00:02:44.200> symmetric<00:02:44.650> every<00:02:44.950> server 00:02:45.900 --> 00:02:45.910 align:start position:0% because they're symmetric every server 00:02:45.910 --> 00:02:48.720 align:start position:0% because they're symmetric every server involved<00:02:46.330> has<00:02:46.780> a<00:02:46.810> similar<00:02:47.710> role<00:02:47.980> there<00:02:48.520> is<00:02:48.580> no 00:02:48.720 --> 00:02:48.730 align:start position:0% involved has a similar role there is no 00:02:48.730 --> 00:02:50.580 align:start position:0% involved has a similar role there is no kind<00:02:48.820> of<00:02:48.910> master<00:02:49.150> slave<00:02:49.510> arrangement<00:02:50.500> like 00:02:50.580 --> 00:02:50.590 align:start position:0% kind of master slave arrangement like 00:02:50.590 --> 00:02:54.120 align:start position:0% kind of master slave arrangement like you<00:02:50.710> see<00:02:50.920> in<00:02:51.330> mysql<00:02:52.500> databases<00:02:53.500> or<00:02:53.860> something 00:02:54.120 --> 00:02:54.130 align:start position:0% you see in mysql databases or something 00:02:54.130 --> 00:02:57.540 align:start position:0% you see in mysql databases or something like<00:02:54.220> that<00:02:54.280> and<00:02:55.500> once<00:02:56.500> these<00:02:56.920> decentralized 00:02:57.540 --> 00:02:57.550 align:start position:0% like that and once these decentralized 00:02:57.550 --> 00:03:02.160 align:start position:0% like that and once these decentralized networks<00:02:57.940> can<00:02:58.090> scale<00:03:01.170> multi-party 00:03:02.160 --> 00:03:02.170 align:start position:0% networks can scale multi-party 00:03:02.170 --> 00:03:04.590 align:start position:0% networks can scale multi-party computation<00:03:02.800> can<00:03:03.250> be<00:03:03.340> introduced<00:03:03.760> to<00:03:03.940> secure 00:03:04.590 --> 00:03:04.600 align:start position:0% computation can be introduced to secure 00:03:04.600 --> 00:03:08.100 align:start position:0% computation can be introduced to secure the<00:03:04.810> data<00:03:05.050> inside<00:03:05.530> them<00:03:05.770> so<00:03:06.600> you<00:03:07.600> probably<00:03:07.900> all 00:03:08.100 --> 00:03:08.110 align:start position:0% the data inside them so you probably all 00:03:08.110 --> 00:03:09.750 align:start position:0% the data inside them so you probably all heard<00:03:08.290> about<00:03:08.410> the<00:03:08.620> hacks<00:03:08.920> that<00:03:09.220> target<00:03:09.670> in 00:03:09.750 --> 00:03:09.760 align:start position:0% heard about the hacks that target in 00:03:09.760 --> 00:03:11.160 align:start position:0% heard about the hacks that target in America<00:03:10.270> and<00:03:10.570> the<00:03:10.630> Office<00:03:10.870> of<00:03:10.990> Personnel 00:03:11.160 --> 00:03:11.170 align:start position:0% America and the Office of Personnel 00:03:11.170 --> 00:03:13.560 align:start position:0% America and the Office of Personnel Management<00:03:11.950> I<00:03:11.980> think<00:03:12.160> in<00:03:12.280> the<00:03:12.370> UK<00:03:12.730> Talk<00:03:13.540> Talk 00:03:13.560 --> 00:03:13.570 align:start position:0% Management I think in the UK Talk Talk 00:03:13.570 --> 00:03:16.710 align:start position:0% Management I think in the UK Talk Talk has<00:03:14.020> just<00:03:14.200> lost<00:03:14.380> a<00:03:14.530> lot<00:03:14.680> of<00:03:14.709> customer<00:03:15.640> data<00:03:15.820> I 00:03:16.710 --> 00:03:16.720 align:start position:0% has just lost a lot of customer data I 00:03:16.720 --> 00:03:18.110 align:start position:0% has just lost a lot of customer data I think<00:03:17.200> we're<00:03:17.290> going<00:03:17.380> to<00:03:17.470> see<00:03:17.530> you<00:03:17.920> know 00:03:18.110 --> 00:03:18.120 align:start position:0% think we're going to see you know 00:03:18.120 --> 00:03:20.580 align:start position:0% think we're going to see you know enterprise<00:03:19.120> decentralized<00:03:19.600> databases<00:03:20.230> where 00:03:20.580 --> 00:03:20.590 align:start position:0% enterprise decentralized databases where 00:03:20.590 --> 00:03:23.490 align:start position:0% enterprise decentralized databases where the<00:03:21.010> data<00:03:21.520> is<00:03:21.700> distributed<00:03:22.150> across<00:03:23.080> a<00:03:23.170> large 00:03:23.490 --> 00:03:23.500 align:start position:0% the data is distributed across a large 00:03:23.500 --> 00:03:25.590 align:start position:0% the data is distributed across a large number<00:03:23.890> of<00:03:23.920> different<00:03:24.370> servers<00:03:24.730> and<00:03:24.910> you<00:03:25.480> can 00:03:25.590 --> 00:03:25.600 align:start position:0% number of different servers and you can 00:03:25.600 --> 00:03:28.729 align:start position:0% number of different servers and you can only<00:03:25.690> access<00:03:25.780> it<00:03:26.290> by<00:03:26.440> running<00:03:27.400> running 00:03:28.729 --> 00:03:28.739 align:start position:0% only access it by running running 00:03:28.739 --> 00:03:33.090 align:start position:0% only access it by running running authorized<00:03:29.739> requests<00:03:30.430> which<00:03:31.980> access<00:03:32.980> the 00:03:33.090 --> 00:03:33.100 align:start position:0% authorized requests which access the 00:03:33.100 --> 00:03:34.380 align:start position:0% authorized requests which access the days<00:03:33.220> are<00:03:33.340> in<00:03:33.370> a<00:03:33.459> certain<00:03:33.640> way<00:03:33.760> you<00:03:34.150> can<00:03:34.300> ask 00:03:34.380 --> 00:03:34.390 align:start position:0% days are in a certain way you can ask 00:03:34.390 --> 00:03:36.720 align:start position:0% days are in a certain way you can ask when<00:03:34.690> you<00:03:34.810> can<00:03:34.989> run<00:03:35.709> a<00:03:35.770> query<00:03:36.040> against<00:03:36.459> the<00:03:36.610> day 00:03:36.720 --> 00:03:36.730 align:start position:0% when you can run a query against the day 00:03:36.730 --> 00:03:38.250 align:start position:0% when you can run a query against the day to<00:03:36.790> say<00:03:37.030> but<00:03:37.090> you<00:03:37.330> can't<00:03:37.570> retrieve<00:03:37.930> all<00:03:38.230> the 00:03:38.250 --> 00:03:38.260 align:start position:0% to say but you can't retrieve all the 00:03:38.260 --> 00:03:40.229 align:start position:0% to say but you can't retrieve all the data<00:03:38.350> from<00:03:38.530> the<00:03:38.680> database<00:03:38.769> so<00:03:39.250> you<00:03:39.940> know<00:03:40.060> with 00:03:40.229 --> 00:03:40.239 align:start position:0% data from the database so you know with 00:03:40.239 --> 00:03:42.570 align:start position:0% data from the database so you know with with<00:03:40.390> a<00:03:40.450> and<00:03:40.989> a<00:03:41.769> decentralized<00:03:42.100> enterprise 00:03:42.570 --> 00:03:42.580 align:start position:0% with a and a decentralized enterprise 00:03:42.580 --> 00:03:44.790 align:start position:0% with a and a decentralized enterprise database<00:03:42.940> which<00:03:43.209> is<00:03:43.239> using<00:03:43.570> NPC<00:03:43.989> all<00:03:44.320> of<00:03:44.680> these 00:03:44.790 --> 00:03:44.800 align:start position:0% database which is using NPC all of these 00:03:44.800 --> 00:03:46.410 align:start position:0% database which is using NPC all of these kind<00:03:45.010> of<00:03:45.040> hacks<00:03:45.310> that<00:03:45.580> you<00:03:45.640> hear<00:03:45.820> about<00:03:45.910> would 00:03:46.410 --> 00:03:46.420 align:start position:0% kind of hacks that you hear about would 00:03:46.420 --> 00:03:51.780 align:start position:0% kind of hacks that you hear about would their<00:03:46.540> laundry<00:03:46.690> possible<00:03:49.350> so 00:03:51.780 --> 00:03:51.790 align:start position:0% their laundry possible so 00:03:51.790 --> 00:03:57.179 align:start position:0% their laundry possible so I<00:03:51.879> think<00:03:53.069> the<00:03:55.260> more<00:03:56.260> specifically<00:03:56.709> for<00:03:56.950> some 00:03:57.179 --> 00:03:57.189 align:start position:0% I think the more specifically for some 00:03:57.189 --> 00:04:02.220 align:start position:0% I think the more specifically for some lesser<00:03:57.879> sister<00:04:00.689> probably<00:04:01.689> in<00:04:01.750> the<00:04:01.810> long<00:04:01.989> term 00:04:02.220 --> 00:04:02.230 align:start position:0% lesser sister probably in the long term 00:04:02.230 --> 00:04:05.729 align:start position:0% lesser sister probably in the long term I<00:04:02.530> think<00:04:03.010> that<00:04:03.640> the<00:04:04.260> scale<00:04:05.260> out<00:04:05.409> kind<00:04:05.680> of 00:04:05.729 --> 00:04:05.739 align:start position:0% I think that the scale out kind of 00:04:05.739 --> 00:04:07.640 align:start position:0% I think that the scale out kind of systems<00:04:06.069> will<00:04:06.250> use<00:04:06.790> a<00:04:06.819> number<00:04:07.120> of<00:04:07.269> different 00:04:07.640 --> 00:04:07.650 align:start position:0% systems will use a number of different 00:04:07.650 --> 00:04:11.670 align:start position:0% systems will use a number of different kinds<00:04:08.650> of<00:04:08.879> consensus<00:04:10.109> system<00:04:11.109> in<00:04:11.290> their 00:04:11.670 --> 00:04:11.680 align:start position:0% kinds of consensus system in their 00:04:11.680 --> 00:04:15.469 align:start position:0% kinds of consensus system in their overall<00:04:12.040> network<00:04:12.370> architecture<00:04:12.970> and<00:04:14.099> this<00:04:15.099> is 00:04:15.469 --> 00:04:15.479 align:start position:0% overall network architecture and this is 00:04:15.479 --> 00:04:19.439 align:start position:0% overall network architecture and this is an<00:04:16.479> architecture<00:04:16.989> that<00:04:17.019> I<00:04:17.169> pursue<00:04:17.639> and<00:04:18.639> you 00:04:19.439 --> 00:04:19.449 align:start position:0% an architecture that I pursue and you 00:04:19.449 --> 00:04:21.390 align:start position:0% an architecture that I pursue and you can<00:04:19.600> see<00:04:19.810> at<00:04:19.930> the<00:04:20.019> very<00:04:20.169> top<00:04:20.410> level<00:04:20.470> them<00:04:20.919> it's 00:04:21.390 --> 00:04:21.400 align:start position:0% can see at the very top level them it's 00:04:21.400 --> 00:04:22.740 align:start position:0% can see at the very top level them it's got<00:04:21.549> several<00:04:21.850> layers<00:04:22.060> you've<00:04:22.270> got<00:04:22.360> a<00:04:22.389> master 00:04:22.740 --> 00:04:22.750 align:start position:0% got several layers you've got a master 00:04:22.750 --> 00:04:24.150 align:start position:0% got several layers you've got a master consensus<00:04:23.259> layer<00:04:23.470> you<00:04:23.620> got<00:04:23.710> a<00:04:23.740> scalable 00:04:24.150 --> 00:04:24.160 align:start position:0% consensus layer you got a scalable 00:04:24.160 --> 00:04:25.469 align:start position:0% consensus layer you got a scalable validation<00:04:24.669> there<00:04:24.820> and<00:04:24.910> you<00:04:24.970> get<00:04:25.060> a<00:04:25.090> storage 00:04:25.469 --> 00:04:25.479 align:start position:0% validation there and you get a storage 00:04:25.479 --> 00:04:28.560 align:start position:0% validation there and you get a storage layer<00:04:26.110> and<00:04:26.530> at<00:04:26.650> the<00:04:26.710> very<00:04:26.740> top<00:04:27.070> level<00:04:27.570> it's 00:04:28.560 --> 00:04:28.570 align:start position:0% layer and at the very top level it's 00:04:28.570 --> 00:04:32.070 align:start position:0% layer and at the very top level it's going<00:04:28.810> to<00:04:28.870> block<00:04:29.050> chain<00:04:29.320> like<00:04:30.900> it's<00:04:31.900> going<00:04:32.050> to 00:04:32.070 --> 00:04:32.080 align:start position:0% going to block chain like it's going to 00:04:32.080 --> 00:04:34.529 align:start position:0% going to block chain like it's going to watching<00:04:32.410> it<00:04:33.009> may<00:04:33.520> not<00:04:33.669> use<00:04:34.090> proof-of-work 00:04:34.529 --> 00:04:34.539 align:start position:0% watching it may not use proof-of-work 00:04:34.539 --> 00:04:36.420 align:start position:0% watching it may not use proof-of-work could<00:04:35.349> use<00:04:35.530> something<00:04:35.740> like<00:04:35.860> Casper<00:04:36.280> or<00:04:36.370> it 00:04:36.420 --> 00:04:36.430 align:start position:0% could use something like Casper or it 00:04:36.430 --> 00:04:40.040 align:start position:0% could use something like Casper or it could<00:04:36.550> use<00:04:36.699> something<00:04:37.240> else<00:04:37.449> altogether<00:04:38.789> but 00:04:40.040 --> 00:04:40.050 align:start position:0% could use something else altogether but 00:04:40.050 --> 00:04:42.570 align:start position:0% could use something else altogether but that's<00:04:41.050> only<00:04:41.169> one<00:04:41.620> component<00:04:42.160> of<00:04:42.460> the<00:04:42.550> overall 00:04:42.570 --> 00:04:42.580 align:start position:0% that's only one component of the overall 00:04:42.580 --> 00:04:45.480 align:start position:0% that's only one component of the overall network<00:04:43.180> we<00:04:43.479> also<00:04:43.630> have<00:04:43.960> this<00:04:44.710> validation 00:04:45.480 --> 00:04:45.490 align:start position:0% network we also have this validation 00:04:45.490 --> 00:04:49.070 align:start position:0% network we also have this validation layer<00:04:46.389> and<00:04:46.599> we<00:04:46.720> have<00:04:46.930> a<00:04:47.169> storage<00:04:47.979> layer<00:04:48.220> and 00:04:49.070 --> 00:04:49.080 align:start position:0% layer and we have a storage layer and 00:04:49.080 --> 00:04:53.120 align:start position:0% layer and we have a storage layer and these<00:04:50.080> green<00:04:50.380> dots<00:04:50.410> these<00:04:51.130> represents 00:04:53.120 --> 00:04:53.130 align:start position:0% these green dots these represents 00:04:53.130 --> 00:04:55.800 align:start position:0% these green dots these represents traditional<00:04:54.130> consensus<00:04:54.729> processes<00:04:55.509> that<00:04:55.690> are 00:04:55.800 --> 00:04:55.810 align:start position:0% traditional consensus processes that are 00:04:55.810 --> 00:04:58.379 align:start position:0% traditional consensus processes that are being<00:04:55.960> run<00:04:56.169> because<00:04:57.030> for<00:04:58.030> various<00:04:58.330> reasons 00:04:58.379 --> 00:04:58.389 align:start position:0% being run because for various reasons 00:04:58.389 --> 00:05:00.570 align:start position:0% being run because for various reasons it's<00:04:58.840> very<00:04:59.050> difficult<00:04:59.260> to<00:04:59.560> create<00:04:59.860> strongly 00:05:00.570 --> 00:05:00.580 align:start position:0% it's very difficult to create strongly 00:05:00.580 --> 00:05:03.029 align:start position:0% it's very difficult to create strongly consistent<00:05:01.210> master<00:05:01.750> chain<00:05:02.530> that<00:05:02.770> is<00:05:02.919> if 00:05:03.029 --> 00:05:03.039 align:start position:0% consistent master chain that is if 00:05:03.039 --> 00:05:04.050 align:start position:0% consistent master chain that is if you're<00:05:03.130> very<00:05:03.430> large<00:05:03.610> number<00:05:03.789> of<00:05:03.909> nodes 00:05:04.050 --> 00:05:04.060 align:start position:0% you're very large number of nodes 00:05:04.060 --> 00:05:05.760 align:start position:0% you're very large number of nodes imagine<00:05:04.479> if<00:05:04.539> you<00:05:04.599> had<00:05:04.630> a<00:05:04.750> million<00:05:04.960> nodes<00:05:05.260> in<00:05:05.650> a 00:05:05.760 --> 00:05:05.770 align:start position:0% imagine if you had a million nodes in a 00:05:05.770 --> 00:05:08.129 align:start position:0% imagine if you had a million nodes in a distributed<00:05:06.400> virtual<00:05:06.699> machine<00:05:07.090> be<00:05:07.870> very 00:05:08.129 --> 00:05:08.139 align:start position:0% distributed virtual machine be very 00:05:08.139 --> 00:05:11.790 align:start position:0% distributed virtual machine be very difficult<00:05:08.289> to<00:05:08.620> have<00:05:09.300> strong<00:05:10.300> consistency<00:05:10.800> at 00:05:11.790 --> 00:05:11.800 align:start position:0% difficult to have strong consistency at 00:05:11.800 --> 00:05:15.390 align:start position:0% difficult to have strong consistency at that<00:05:11.979> level<00:05:12.159> so<00:05:12.960> if<00:05:13.960> if<00:05:14.289> the<00:05:14.320> master<00:05:14.860> chain<00:05:15.220> can 00:05:15.390 --> 00:05:15.400 align:start position:0% that level so if if the master chain can 00:05:15.400 --> 00:05:17.430 align:start position:0% that level so if if the master chain can reorganize<00:05:15.580> itself<00:05:16.030> and<00:05:16.330> drive<00:05:16.539> other 00:05:17.430 --> 00:05:17.440 align:start position:0% reorganize itself and drive other 00:05:17.440 --> 00:05:19.409 align:start position:0% reorganize itself and drive other changes<00:05:17.860> lower<00:05:18.070> low<00:05:18.370> down<00:05:18.610> we<00:05:18.760> don't<00:05:18.970> want<00:05:19.150> to 00:05:19.409 --> 00:05:19.419 align:start position:0% changes lower low down we don't want to 00:05:19.419 --> 00:05:23.010 align:start position:0% changes lower low down we don't want to have<00:05:19.570> weekly<00:05:20.409> consistent<00:05:21.190> to<00:05:21.940> be<00:05:22.360> you<00:05:22.900> know 00:05:23.010 --> 00:05:23.020 align:start position:0% have weekly consistent to be you know 00:05:23.020 --> 00:05:24.960 align:start position:0% have weekly consistent to be you know composing<00:05:23.620> weekly<00:05:23.919> consistent<00:05:24.460> consensus 00:05:24.960 --> 00:05:24.970 align:start position:0% composing weekly consistent consensus 00:05:24.970 --> 00:05:28.800 align:start position:0% composing weekly consistent consensus process<00:05:25.630> is<00:05:25.930> further<00:05:26.139> down<00:05:26.380> so<00:05:27.659> you<00:05:28.659> know 00:05:28.800 --> 00:05:28.810 align:start position:0% process is further down so you know 00:05:28.810 --> 00:05:30.450 align:start position:0% process is further down so you know consensus<00:05:29.650> really<00:05:29.860> does<00:05:30.010> have<00:05:30.159> a<00:05:30.220> really 00:05:30.450 --> 00:05:30.460 align:start position:0% consensus really does have a really 00:05:30.460 --> 00:05:33.390 align:start position:0% consensus really does have a really important<00:05:30.820> role<00:05:30.970> to<00:05:31.000> play<00:05:31.270> in<00:05:32.099> creating<00:05:33.099> these 00:05:33.390 --> 00:05:33.400 align:start position:0% important role to play in creating these 00:05:33.400 --> 00:05:36.149 align:start position:0% important role to play in creating these kinds<00:05:33.789> of<00:05:33.820> network<00:05:34.150> and<00:05:34.470> in<00:05:35.470> this<00:05:35.949> diagram 00:05:36.149 --> 00:05:36.159 align:start position:0% kinds of network and in this diagram 00:05:36.159 --> 00:05:38.629 align:start position:0% kinds of network and in this diagram here<00:05:36.490> these<00:05:36.699> green<00:05:36.940> dots<00:05:36.970> are<00:05:37.510> in<00:05:37.630> fact 00:05:38.629 --> 00:05:38.639 align:start position:0% here these green dots are in fact 00:05:38.639 --> 00:05:43.220 align:start position:0% here these green dots are in fact traditional<00:05:39.639> consensus<00:05:40.240> instances<00:05:40.949> soon 00:05:43.220 --> 00:05:43.230 align:start position:0% traditional consensus instances soon 00:05:43.230 --> 00:05:45.960 align:start position:0% traditional consensus instances soon what<00:05:44.230> is<00:05:44.380> the<00:05:44.530> sort<00:05:44.860> of<00:05:44.890> xan<00:05:45.430> team<00:05:45.610> consensus 00:05:45.960 --> 00:05:45.970 align:start position:0% what is the sort of xan team consensus 00:05:45.970 --> 00:05:50.490 align:start position:0% what is the sort of xan team consensus challenge<00:05:48.870> very<00:05:49.870> basically<00:05:50.140> you've<00:05:50.350> got<00:05:50.470> a 00:05:50.490 --> 00:05:50.500 align:start position:0% challenge very basically you've got a 00:05:50.500 --> 00:05:53.790 align:start position:0% challenge very basically you've got a bunch<00:05:50.710> of<00:05:51.150> nodes<00:05:52.150> that<00:05:52.840> are<00:05:53.230> connected<00:05:53.680> by 00:05:53.790 --> 00:05:53.800 align:start position:0% bunch of nodes that are connected by 00:05:53.800 --> 00:05:56.280 align:start position:0% bunch of nodes that are connected by some<00:05:54.070> kind<00:05:54.280> of<00:05:54.340> network<00:05:54.990> here<00:05:55.990> are<00:05:56.110> cool<00:05:56.260> man 00:05:56.280 --> 00:05:56.290 align:start position:0% some kind of network here are cool man 00:05:56.290 --> 00:05:59.130 align:start position:0% some kind of network here are cool man processes<00:05:56.860> so<00:05:57.190> I'll<00:05:57.250> try<00:05:57.460> and<00:05:57.490> use<00:05:57.940> that<00:05:58.140> non 00:05:59.130 --> 00:05:59.140 align:start position:0% processes so I'll try and use that non 00:05:59.140 --> 00:06:03.210 align:start position:0% processes so I'll try and use that non closure<00:05:59.580> and<00:06:01.170> then<00:06:02.170> you'll<00:06:02.290> have<00:06:02.470> a<00:06:02.740> value 00:06:03.210 --> 00:06:03.220 align:start position:0% closure and then you'll have a value 00:06:03.220 --> 00:06:04.380 align:start position:0% closure and then you'll have a value that<00:06:03.340> they<00:06:03.550> want<00:06:03.730> to<00:06:03.790> propose<00:06:04.030> and<00:06:04.300> they've 00:06:04.380 --> 00:06:04.390 align:start position:0% that they want to propose and they've 00:06:04.390 --> 00:06:06.450 align:start position:0% that they want to propose and they've got<00:06:04.420> to<00:06:04.600> agree<00:06:04.690> on<00:06:04.900> this<00:06:05.410> value<00:06:05.740> and<00:06:05.950> the 00:06:06.450 --> 00:06:06.460 align:start position:0% got to agree on this value and the 00:06:06.460 --> 00:06:07.740 align:start position:0% got to agree on this value and the important<00:06:06.820> point<00:06:07.000> is<00:06:07.120> that<00:06:07.150> some<00:06:07.600> of<00:06:07.690> these 00:06:07.740 --> 00:06:07.750 align:start position:0% important point is that some of these 00:06:07.750 --> 00:06:09.720 align:start position:0% important point is that some of these most<00:06:08.440> of<00:06:08.560> these<00:06:08.650> nodes<00:06:08.800> are<00:06:09.010> correct<00:06:09.370> which 00:06:09.720 --> 00:06:09.730 align:start position:0% most of these nodes are correct which 00:06:09.730 --> 00:06:12.510 align:start position:0% most of these nodes are correct which means<00:06:10.000> they<00:06:10.270> follow<00:06:11.020> the<00:06:11.170> protocol<00:06:11.590> but<00:06:12.310> some 00:06:12.510 --> 00:06:12.520 align:start position:0% means they follow the protocol but some 00:06:12.520 --> 00:06:14.400 align:start position:0% means they follow the protocol but some of<00:06:12.610> them<00:06:12.670> are<00:06:12.760> faulty<00:06:13.120> and<00:06:13.360> that<00:06:13.960> means<00:06:14.140> they 00:06:14.400 --> 00:06:14.410 align:start position:0% of them are faulty and that means they 00:06:14.410 --> 00:06:16.950 align:start position:0% of them are faulty and that means they can<00:06:14.590> behave<00:06:14.770> completely<00:06:15.010> arbitrarily<00:06:15.960> which 00:06:16.950 --> 00:06:16.960 align:start position:0% can behave completely arbitrarily which 00:06:16.960 --> 00:06:22.650 align:start position:0% can behave completely arbitrarily which is<00:06:17.140> what<00:06:17.470> is<00:06:17.530> meant<00:06:17.680> by<00:06:17.740> presenting<00:06:21.480> so<00:06:22.480> what 00:06:22.650 --> 00:06:22.660 align:start position:0% is what is meant by presenting so what 00:06:22.660 --> 00:06:25.110 align:start position:0% is what is meant by presenting so what is<00:06:22.750> Byzantium<00:06:23.290> consensus<00:06:23.920> so<00:06:24.040> I<00:06:24.100> it's<00:06:25.030> the 00:06:25.110 --> 00:06:25.120 align:start position:0% is Byzantium consensus so I it's the 00:06:25.120 --> 00:06:26.700 align:start position:0% is Byzantium consensus so I it's the easiest<00:06:25.360> way<00:06:25.510> to<00:06:25.570> think<00:06:25.750> about<00:06:25.900> it<00:06:26.050> is<00:06:26.320> as<00:06:26.650> a 00:06:26.700 --> 00:06:26.710 align:start position:0% easiest way to think about it is as a 00:06:26.710 --> 00:06:31.620 align:start position:0% easiest way to think about it is as a game<00:06:27.420> the<00:06:28.420> correct<00:06:29.050> processes<00:06:30.480> run<00:06:31.480> this 00:06:31.620 --> 00:06:31.630 align:start position:0% game the correct processes run this 00:06:31.630 --> 00:06:33.360 align:start position:0% game the correct processes run this protocol<00:06:32.110> and<00:06:32.380> try<00:06:32.620> and<00:06:32.680> reach<00:06:32.830> agreement<00:06:33.280> by 00:06:33.360 --> 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anniversary try to either prevent<00:06:41.590> consensus<00:06:42.250> being<00:06:42.430> reached<00:06:42.640> or<00:06:43.030> to 00:06:43.740 --> 00:06:43.750 align:start position:0% prevent consensus being reached or to 00:06:43.750 --> 00:06:47.970 align:start position:0% prevent consensus being reached or to make<00:06:44.050> correct<00:06:44.380> nodes<00:06:45.120> decide<00:06:46.650> invalid<00:06:47.650> values 00:06:47.970 --> 00:06:47.980 align:start position:0% make correct nodes decide invalid values 00:06:47.980 --> 00:06:49.320 align:start position:0% make correct nodes decide invalid values that<00:06:48.130> is<00:06:48.280> think<00:06:48.520> they've<00:06:48.670> reached<00:06:48.820> agreement 00:06:49.320 --> 00:06:49.330 align:start position:0% that is think they've reached agreement 00:06:49.330 --> 00:06:52.380 align:start position:0% that is think they've reached agreement on<00:06:49.390> something<00:06:49.600> that<00:06:49.870> they<00:06:50.110> happen<00:06:51.210> so<00:06:52.210> on 00:06:52.380 --> 00:06:52.390 align:start position:0% on something that they happen so on 00:06:52.390 --> 00:06:55.280 align:start position:0% on something that they happen so on these<00:06:52.630> 1402<00:06:53.340> processes<00:06:54.340> what<00:06:54.490> can<00:06:54.610> they<00:06:54.700> do 00:06:55.280 --> 00:06:55.290 align:start position:0% these 1402 processes what can they do 00:06:55.290 --> 00:06:57.720 align:start position:0% these 1402 processes what can they do their<00:06:56.290> Byzantine<00:06:56.830> and<00:06:56.860> what<00:06:57.220> that<00:06:57.340> means<00:06:57.550> is 00:06:57.720 --> 00:06:57.730 align:start position:0% their Byzantine and what that means is 00:06:57.730 --> 00:07:01.560 align:start position:0% their Byzantine and what that means is they<00:06:57.970> can<00:06:58.270> adopt<00:06:58.980> arbitrary<00:06:59.980> tactics<00:07:00.580> they 00:07:01.560 --> 00:07:01.570 align:start position:0% they can adopt arbitrary tactics they 00:07:01.570 --> 00:07:04.200 align:start position:0% they can adopt arbitrary tactics they can<00:07:01.840> just<00:07:02.110> decide<00:07:02.380> to<00:07:02.620> crash<00:07:02.950> and<00:07:03.220> fail<00:07:03.460> they 00:07:04.200 --> 00:07:04.210 align:start position:0% can just decide to crash and fail they 00:07:04.210 --> 00:07:07.890 align:start position:0% can just decide to crash and fail they can<00:07:04.920> corrupt<00:07:05.920> data<00:07:06.310> and<00:07:06.580> messages<00:07:07.000> they<00:07:07.660> can 00:07:07.890 --> 00:07:07.900 align:start position:0% can corrupt data and messages they can 00:07:07.900 --> 00:07:10.200 align:start position:0% can corrupt data and messages they can subtly<00:07:08.460> subvert<00:07:09.460> the<00:07:09.580> communications 00:07:10.200 --> 00:07:10.210 align:start position:0% subtly subvert the communications 00:07:10.210 --> 00:07:12.180 align:start position:0% subtly subvert the communications protocol<00:07:10.660> and<00:07:10.900> they<00:07:11.260> can<00:07:11.440> coordinate<00:07:11.890> their 00:07:12.180 --> 00:07:12.190 align:start position:0% protocol and they can coordinate their 00:07:12.190 --> 00:07:14.490 align:start position:0% protocol and they can coordinate their their<00:07:12.490> actions<00:07:12.880> so<00:07:13.780> they<00:07:13.930> really<00:07:14.140> can<00:07:14.350> do 00:07:14.490 --> 00:07:14.500 align:start position:0% their actions so they really can do 00:07:14.500 --> 00:07:19.290 align:start position:0% their actions so they really can do anything<00:07:14.890> at<00:07:15.130> all<00:07:17.940> depending<00:07:18.940> on<00:07:19.060> the<00:07:19.150> model 00:07:19.290 --> 00:07:19.300 align:start position:0% anything at all depending on the model 00:07:19.300 --> 00:07:21.240 align:start position:0% anything at all depending on the model that's<00:07:19.600> being<00:07:19.780> used<00:07:19.870> the<00:07:20.530> adversary<00:07:20.980> can<00:07:21.100> also 00:07:21.240 --> 00:07:21.250 align:start position:0% that's being used the adversary can also 00:07:21.250 --> 00:07:23.640 align:start position:0% that's being used the adversary can also do<00:07:21.460> things<00:07:21.580> like<00:07:21.730> controlling<00:07:22.360> the<00:07:22.720> control 00:07:23.640 --> 00:07:23.650 align:start position:0% do things like controlling the control 00:07:23.650 --> 00:07:25.950 align:start position:0% do things like controlling the control the<00:07:23.770> scheduling<00:07:24.220> and<00:07:24.370> messages<00:07:24.790> right<00:07:25.540> it<00:07:25.780> can 00:07:25.950 --> 00:07:25.960 align:start position:0% the scheduling and messages right it can 00:07:25.960 --> 00:07:28.830 align:start position:0% the scheduling and messages right it can impact<00:07:26.530> the<00:07:26.800> network<00:07:27.210> he<00:07:28.210> may<00:07:28.420> have<00:07:28.450> full 00:07:28.830 --> 00:07:28.840 align:start position:0% impact the network he may have full 00:07:28.840 --> 00:07:31.650 align:start position:0% impact the network he may have full information<00:07:28.990> about<00:07:29.560> process<00:07:30.040> States<00:07:30.310> and<00:07:30.660> he 00:07:31.650 --> 00:07:31.660 align:start position:0% information about process States and he 00:07:31.660 --> 00:07:34.080 align:start position:0% information about process States and he can<00:07:31.930> during<00:07:32.650> the<00:07:32.770> consensus<00:07:33.280> protocol<00:07:34.000> you 00:07:34.080 --> 00:07:34.090 align:start position:0% can during the consensus protocol you 00:07:34.090 --> 00:07:39.440 align:start position:0% can during the consensus protocol you can<00:07:35.010> corrupt<00:07:36.010> correct<00:07:36.490> nodes<00:07:36.670> at<00:07:36.850> will<00:07:38.220> so 00:07:39.440 --> 00:07:39.450 align:start position:0% can corrupt correct nodes at will so 00:07:39.450 --> 00:07:43.710 align:start position:0% can corrupt correct nodes at will so just<00:07:40.450> to<00:07:40.540> clarify<00:07:41.730> what<00:07:42.730> consensus<00:07:43.270> is<00:07:43.450> the 00:07:43.710 --> 00:07:43.720 align:start position:0% just to clarify what consensus is the 00:07:43.720 --> 00:07:47.400 align:start position:0% just to clarify what consensus is the first<00:07:44.680> of<00:07:44.830> all<00:07:44.950> consensus<00:07:45.580> is<00:07:45.760> agreement<00:07:46.410> here 00:07:47.400 --> 00:07:47.410 align:start position:0% first of all consensus is agreement here 00:07:47.410 --> 00:07:48.760 align:start position:0% first of all consensus is agreement here we<00:07:47.560> have 00:07:48.760 --> 00:07:48.770 align:start position:0% we have 00:07:48.770 --> 00:07:51.129 align:start position:0% we have network<00:07:49.639> of<00:07:49.759> just<00:07:50.000> four<00:07:50.150> nodes<00:07:50.360> the<00:07:50.960> green 00:07:51.129 --> 00:07:51.139 align:start position:0% network of just four nodes the green 00:07:51.139 --> 00:07:52.480 align:start position:0% network of just four nodes the green ones<00:07:51.349> are<00:07:51.470> correct<00:07:51.800> and<00:07:51.949> the<00:07:52.039> red<00:07:52.190> one<00:07:52.370> is 00:07:52.480 --> 00:07:52.490 align:start position:0% ones are correct and the red one is 00:07:52.490 --> 00:07:56.409 align:start position:0% ones are correct and the red one is faulty<00:07:52.849> and<00:07:53.500> the<00:07:54.500> green<00:07:55.099> cracks<00:07:55.759> nodes<00:07:56.060> all 00:07:56.409 --> 00:07:56.419 align:start position:0% faulty and the green cracks nodes all 00:07:56.419 --> 00:07:58.930 align:start position:0% faulty and the green cracks nodes all start<00:07:56.720> off<00:07:56.840> wanting<00:07:57.229> to<00:07:58.069> propose<00:07:58.400> different 00:07:58.930 --> 00:07:58.940 align:start position:0% start off wanting to propose different 00:07:58.940 --> 00:08:02.020 align:start position:0% start off wanting to propose different values<00:07:59.840> and<00:08:00.169> after<00:08:01.099> consensus<00:08:01.639> is<00:08:01.819> run 00:08:02.020 --> 00:08:02.030 align:start position:0% values and after consensus is run 00:08:02.030 --> 00:08:04.510 align:start position:0% values and after consensus is run they've<00:08:02.240> all<00:08:02.360> agreed<00:08:02.449> on<00:08:02.960> the<00:08:03.169> same<00:08:03.199> value<00:08:03.800> XYZ 00:08:04.510 --> 00:08:04.520 align:start position:0% they've all agreed on the same value XYZ 00:08:04.520 --> 00:08:11.460 align:start position:0% they've all agreed on the same value XYZ and<00:08:04.759> that's<00:08:05.750> I<00:08:06.940> guess<00:08:07.940> pretty<00:08:08.270> intuitive 00:08:11.460 --> 00:08:11.470 align:start position:0% 00:08:11.470 --> 00:08:13.930 align:start position:0% agreement<00:08:12.470> source<00:08:12.680> of<00:08:12.830> validity<00:08:13.099> noting<00:08:13.849> in 00:08:13.930 --> 00:08:13.940 align:start position:0% agreement source of validity noting in 00:08:13.940 --> 00:08:21.070 align:start position:0% agreement source of validity noting in this<00:08:14.120> case<00:08:14.389> means<00:08:14.900> that<00:08:16.690> if<00:08:18.460> all<00:08:19.460> the<00:08:20.080> nodes 00:08:21.070 --> 00:08:21.080 align:start position:0% this case means that if all the nodes 00:08:21.080 --> 00:08:24.339 align:start position:0% this case means that if all the nodes start<00:08:21.740> off<00:08:21.860> proposing<00:08:22.460> the<00:08:22.550> same<00:08:22.789> value<00:08:23.349> then 00:08:24.339 --> 00:08:24.349 align:start position:0% start off proposing the same value then 00:08:24.349 --> 00:08:27.580 align:start position:0% start off proposing the same value then they<00:08:24.620> decide<00:08:25.130> that<00:08:25.159> same<00:08:25.759> value<00:08:26.150> and<00:08:26.590> there's 00:08:27.580 --> 00:08:27.590 align:start position:0% they decide that same value and there's 00:08:27.590 --> 00:08:28.809 align:start position:0% they decide that same value and there's two<00:08:27.770> forms<00:08:28.069> of<00:08:28.130> this<00:08:28.280> actually<00:08:28.610> there's 00:08:28.809 --> 00:08:28.819 align:start position:0% two forms of this actually there's 00:08:28.819 --> 00:08:33.310 align:start position:0% two forms of this actually there's there's<00:08:29.180> week<00:08:29.930> validity<00:08:30.650> which<00:08:32.320> requires 00:08:33.310 --> 00:08:33.320 align:start position:0% there's week validity which requires 00:08:33.320 --> 00:08:35.980 align:start position:0% there's week validity which requires that<00:08:33.620> every<00:08:33.860> single<00:08:34.399> and<00:08:34.729> process<00:08:35.510> starts<00:08:35.839> off 00:08:35.980 --> 00:08:35.990 align:start position:0% that every single and process starts off 00:08:35.990 --> 00:08:38.500 align:start position:0% that every single and process starts off proposing<00:08:36.469> the<00:08:36.620> same<00:08:36.940> value<00:08:37.940> and<00:08:38.120> the<00:08:38.180> strong 00:08:38.500 --> 00:08:38.510 align:start position:0% proposing the same value and the strong 00:08:38.510 --> 00:08:40.959 align:start position:0% proposing the same value and the strong validity<00:08:39.349> which<00:08:39.649> requires<00:08:40.070> that<00:08:40.370> only<00:08:40.789> the 00:08:40.959 --> 00:08:40.969 align:start position:0% validity which requires that only the 00:08:40.969 --> 00:08:45.250 align:start position:0% validity which requires that only the correct<00:08:42.700> processes<00:08:43.700> need<00:08:44.029> stop<00:08:44.329> to<00:08:44.930> start<00:08:45.170> off 00:08:45.250 --> 00:08:45.260 align:start position:0% correct processes need stop to start off 00:08:45.260 --> 00:08:47.380 align:start position:0% correct processes need stop to start off proposing<00:08:45.860> the<00:08:45.920> same<00:08:46.100> value<00:08:46.339> anyway<00:08:46.700> in<00:08:46.910> this 00:08:47.380 --> 00:08:47.390 align:start position:0% proposing the same value anyway in this 00:08:47.390 --> 00:08:50.050 align:start position:0% proposing the same value anyway in this diagram<00:08:47.870> here<00:08:48.170> all<00:08:48.950> of<00:08:49.010> the<00:08:49.220> processes<00:08:49.640> have 00:08:50.050 --> 00:08:50.060 align:start position:0% diagram here all of the processes have 00:08:50.060 --> 00:08:53.519 align:start position:0% diagram here all of the processes have started<00:08:50.510> started<00:08:51.290> off<00:08:51.500> proposing<00:08:52.010> and<00:08:52.160> mo<00:08:52.459> and 00:08:53.519 --> 00:08:53.529 align:start position:0% started started off proposing and mo and 00:08:53.529 --> 00:08:55.740 align:start position:0% started started off proposing and mo and after<00:08:54.529> consensus<00:08:55.040> all<00:08:55.250> of<00:08:55.399> the<00:08:55.490> correct 00:08:55.740 --> 00:08:55.750 align:start position:0% after consensus all of the correct 00:08:55.750 --> 00:09:00.970 align:start position:0% after consensus all of the correct processes<00:08:57.520> have<00:08:58.520> decided<00:08:59.390> an<00:08:59.510> NM<00:09:00.020> o<00:09:00.140> of<00:09:00.740> course 00:09:00.970 --> 00:09:00.980 align:start position:0% processes have decided an NM o of course 00:09:00.980 --> 00:09:03.040 align:start position:0% processes have decided an NM o of course the<00:09:01.220> faulty<00:09:01.670> process<00:09:02.029> has<00:09:02.180> come<00:09:02.360> up<00:09:02.420> with<00:09:02.570> XYZ 00:09:03.040 --> 00:09:03.050 align:start position:0% the faulty process has come up with XYZ 00:09:03.050 --> 00:09:05.710 align:start position:0% the faulty process has come up with XYZ it<00:09:03.320> could<00:09:03.470> be<00:09:03.529> anything<00:09:04.149> it's<00:09:05.149> faulty<00:09:05.510> it<00:09:05.600> can 00:09:05.710 --> 00:09:05.720 align:start position:0% it could be anything it's faulty it can 00:09:05.720 --> 00:09:09.090 align:start position:0% it could be anything it's faulty it can do<00:09:05.810> what<00:09:05.930> it<00:09:06.020> likes<00:09:06.050> can<00:09:06.680> behave<00:09:06.860> arbitrarily 00:09:09.090 --> 00:09:09.100 align:start position:0% do what it likes can behave arbitrarily 00:09:09.100 --> 00:09:14.050 align:start position:0% do what it likes can behave arbitrarily so<00:09:10.100> this<00:09:10.399> is<00:09:10.579> um<00:09:11.470> an<00:09:12.470> important<00:09:13.070> one<00:09:13.160> consensus 00:09:14.050 --> 00:09:14.060 align:start position:0% so this is um an important one consensus 00:09:14.060 --> 00:09:18.069 align:start position:0% so this is um an important one consensus is<00:09:14.209> also<00:09:14.540> termination<00:09:15.579> or<00:09:16.750> what<00:09:17.750> that<00:09:17.779> means 00:09:18.069 --> 00:09:18.079 align:start position:0% is also termination or what that means 00:09:18.079 --> 00:09:21.280 align:start position:0% is also termination or what that means is<00:09:18.260> that<00:09:18.290> the<00:09:19.510> before<00:09:20.510> contentious<00:09:20.870> protocol 00:09:21.280 --> 00:09:21.290 align:start position:0% is that the before contentious protocol 00:09:21.290 --> 00:09:25.389 align:start position:0% is that the before contentious protocol that<00:09:22.040> it<00:09:22.160> would<00:09:22.490> eventually<00:09:22.700> terminate<00:09:24.399> it 00:09:25.389 --> 00:09:25.399 align:start position:0% that it would eventually terminate it 00:09:25.399 --> 00:09:28.180 align:start position:0% that it would eventually terminate it can't<00:09:25.700> go<00:09:25.970> on<00:09:26.000> forever<00:09:26.240> that's<00:09:26.870> a<00:09:27.440> valid 00:09:28.180 --> 00:09:28.190 align:start position:0% can't go on forever that's a valid 00:09:28.190 --> 00:09:34.470 align:start position:0% can't go on forever that's a valid consensus<00:09:28.760> protocol<00:09:29.120> has<00:09:29.300> has<00:09:29.690> to<00:09:29.839> terminate 00:09:34.470 --> 00:09:34.480 align:start position:0% 00:09:34.480 --> 00:09:39.040 align:start position:0% so<00:09:35.480> as<00:09:35.839> you<00:09:36.680> probably<00:09:36.950> guessed<00:09:37.750> listening<00:09:38.750> so 00:09:39.040 --> 00:09:39.050 align:start position:0% so as you probably guessed listening so 00:09:39.050 --> 00:09:42.550 align:start position:0% so as you probably guessed listening so far<00:09:39.290> as<00:09:39.520> there<00:09:40.520> are<00:09:40.579> actually<00:09:41.050> many<00:09:42.050> different 00:09:42.550 --> 00:09:42.560 align:start position:0% far as there are actually many different 00:09:42.560 --> 00:09:44.949 align:start position:0% far as there are actually many different models<00:09:43.399> that<00:09:44.300> these<00:09:44.420> consensus 00:09:44.949 --> 00:09:44.959 align:start position:0% models that these consensus 00:09:44.959 --> 00:09:47.740 align:start position:0% models that these consensus protocols<00:09:45.410> are<00:09:45.680> designed<00:09:46.010> to<00:09:46.130> work<00:09:46.430> for<00:09:46.790> and 00:09:47.740 --> 00:09:47.750 align:start position:0% protocols are designed to work for and 00:09:47.750 --> 00:09:53.079 align:start position:0% protocols are designed to work for and so<00:09:48.079> here<00:09:48.290> some<00:09:48.890> of<00:09:48.980> the<00:09:49.839> main<00:09:50.839> ones<00:09:51.910> first<00:09:52.910> one 00:09:53.079 --> 00:09:53.089 align:start position:0% so here some of the main ones first one 00:09:53.089 --> 00:09:55.129 align:start position:0% so here some of the main ones first one is<00:09:53.240> network<00:09:54.020> behavior 00:09:55.129 --> 00:09:55.139 align:start position:0% is network behavior 00:09:55.139 --> 00:09:58.579 align:start position:0% is network behavior and<00:09:56.420> generally<00:09:57.420> speaking<00:09:57.869> consensus 00:09:58.579 --> 00:09:58.589 align:start position:0% and generally speaking consensus 00:09:58.589 --> 00:10:01.369 align:start position:0% and generally speaking consensus protocols<00:09:59.009> are<00:09:59.839> divided<00:10:00.839> into<00:10:00.989> synchronous 00:10:01.369 --> 00:10:01.379 align:start position:0% protocols are divided into synchronous 00:10:01.379 --> 00:10:02.869 align:start position:0% protocols are divided into synchronous consensus<00:10:02.069> protocols<00:10:02.459> and<00:10:02.549> partly 00:10:02.869 --> 00:10:02.879 align:start position:0% consensus protocols and partly 00:10:02.879 --> 00:10:04.249 align:start position:0% consensus protocols and partly synchronous<00:10:03.269> consensus<00:10:03.720> protocols<00:10:04.139> and 00:10:04.249 --> 00:10:04.259 align:start position:0% synchronous consensus protocols and 00:10:04.259 --> 00:10:06.379 align:start position:0% synchronous consensus protocols and asynchronous<00:10:04.859> protocols<00:10:05.279> and<00:10:05.910> in 00:10:06.379 --> 00:10:06.389 align:start position:0% asynchronous protocols and in 00:10:06.389 --> 00:10:10.309 align:start position:0% asynchronous protocols and in synchronous<00:10:06.929> protocols<00:10:08.179> the<00:10:09.179> network<00:10:09.720> is 00:10:10.309 --> 00:10:10.319 align:start position:0% synchronous protocols the network is 00:10:10.319 --> 00:10:14.389 align:start position:0% synchronous protocols the network is assumed<00:10:11.249> to<00:10:11.399> deliver<00:10:12.829> messages<00:10:13.829> within<00:10:14.069> some 00:10:14.389 --> 00:10:14.399 align:start position:0% assumed to deliver messages within some 00:10:14.399 --> 00:10:17.179 align:start position:0% assumed to deliver messages within some bounded<00:10:14.910> predictable<00:10:15.449> time<00:10:15.689> and<00:10:16.189> in 00:10:17.179 --> 00:10:17.189 align:start position:0% bounded predictable time and in 00:10:17.189 --> 00:10:19.729 align:start position:0% bounded predictable time and in asynchronous<00:10:17.850> networks<00:10:18.529> there<00:10:19.529> are<00:10:19.619> no 00:10:19.729 --> 00:10:19.739 align:start position:0% asynchronous networks there are no 00:10:19.739 --> 00:10:23.059 align:start position:0% asynchronous networks there are no timing<00:10:20.129> assumptions<00:10:20.549> whatsoever<00:10:21.709> so<00:10:22.709> and 00:10:23.059 --> 00:10:23.069 align:start position:0% timing assumptions whatsoever so and 00:10:23.069 --> 00:10:24.949 align:start position:0% timing assumptions whatsoever so and this<00:10:23.459> actually<00:10:23.639> is<00:10:23.850> kind<00:10:24.179> of<00:10:24.239> realistic<00:10:24.689> for 00:10:24.949 --> 00:10:24.959 align:start position:0% this actually is kind of realistic for 00:10:24.959 --> 00:10:27.409 align:start position:0% this actually is kind of realistic for the<00:10:25.019> internet<00:10:25.379> right<00:10:25.619> you<00:10:25.980> can<00:10:26.129> get<00:10:26.419> arbitrary 00:10:27.409 --> 00:10:27.419 align:start position:0% the internet right you can get arbitrary 00:10:27.419 --> 00:10:29.590 align:start position:0% the internet right you can get arbitrary partitions<00:10:27.989> a<00:10:28.169> correct<00:10:28.679> node<00:10:28.889> can<00:10:29.100> be<00:10:29.220> deduced 00:10:29.590 --> 00:10:29.600 align:start position:0% partitions a correct node can be deduced 00:10:29.600 --> 00:10:36.139 align:start position:0% partitions a correct node can be deduced right<00:10:30.600> and<00:10:34.220> the<00:10:35.220> second<00:10:35.609> one<00:10:35.699> of<00:10:35.730> course<00:10:35.819> is 00:10:36.139 --> 00:10:36.149 align:start position:0% right and the second one of course is 00:10:36.149 --> 00:10:39.769 align:start position:0% right and the second one of course is the<00:10:36.419> fault<00:10:36.749> type<00:10:37.079> so<00:10:38.419> this<00:10:39.419> is<00:10:39.569> a<00:10:39.600> pretty 00:10:39.769 --> 00:10:39.779 align:start position:0% the fault type so this is a pretty 00:10:39.779 --> 00:10:43.039 align:start position:0% the fault type so this is a pretty oversimplification<00:10:40.709> but<00:10:41.269> the<00:10:42.269> pretty<00:10:42.749> heaven 00:10:43.039 --> 00:10:43.049 align:start position:0% oversimplification but the pretty heaven 00:10:43.049 --> 00:10:45.729 align:start position:0% oversimplification but the pretty heaven consensus<00:10:43.949> algorithm<00:10:44.189> called<00:10:44.459> pack<00:10:44.699> sauce 00:10:45.729 --> 00:10:45.739 align:start position:0% consensus algorithm called pack sauce 00:10:45.739 --> 00:10:48.139 align:start position:0% consensus algorithm called pack sauce anyone<00:10:46.739> it<00:10:46.889> so<00:10:47.129> use<00:10:47.279> it<00:10:47.309> was<00:10:47.549> use<00:10:47.699> it's<00:10:47.879> used<00:10:48.029> in 00:10:48.139 --> 00:10:48.149 align:start position:0% anyone it so use it was use it's used in 00:10:48.149 --> 00:10:50.449 align:start position:0% anyone it so use it was use it's used in like<00:10:48.269> Google<00:10:48.689> chubby<00:10:49.079> and<00:10:49.319> thanks<00:10:49.799> possibly 00:10:50.449 --> 00:10:50.459 align:start position:0% like Google chubby and thanks possibly 00:10:50.459 --> 00:10:52.929 align:start position:0% like Google chubby and thanks possibly zookeeper<00:10:50.879> and<00:10:50.970> things<00:10:51.149> like<00:10:51.269> that<00:10:51.329> so<00:10:52.259> it's<00:10:52.410> a 00:10:52.929 --> 00:10:52.939 align:start position:0% zookeeper and things like that so it's a 00:10:52.939 --> 00:10:55.369 align:start position:0% zookeeper and things like that so it's a consensus<00:10:53.939> algorithm<00:10:54.209> where<00:10:54.660> the<00:10:54.809> only<00:10:55.049> kinds 00:10:55.369 --> 00:10:55.379 align:start position:0% consensus algorithm where the only kinds 00:10:55.379 --> 00:10:57.169 align:start position:0% consensus algorithm where the only kinds of<00:10:55.499> faults<00:10:55.859> that<00:10:55.919> are<00:10:56.040> handled<00:10:56.459> a<00:10:56.549> crash<00:10:56.850> fault 00:10:57.169 --> 00:10:57.179 align:start position:0% of faults that are handled a crash fault 00:10:57.179 --> 00:10:59.989 align:start position:0% of faults that are handled a crash fault so<00:10:57.480> it<00:10:57.540> can<00:10:57.720> deal<00:10:57.929> with<00:10:58.459> processes<00:10:59.459> crashing 00:10:59.989 --> 00:10:59.999 align:start position:0% so it can deal with processes crashing 00:10:59.999 --> 00:11:01.970 align:start position:0% so it can deal with processes crashing but<00:11:00.179> it<00:11:00.269> can't<00:11:00.540> deal<00:11:01.439> with<00:11:01.589> them<00:11:01.709> behaving 00:11:01.970 --> 00:11:01.980 align:start position:0% but it can't deal with them behaving 00:11:01.980 --> 00:11:04.939 align:start position:0% but it can't deal with them behaving arbitrarily<00:11:02.489> and<00:11:02.850> of<00:11:03.360> course<00:11:03.509> the<00:11:03.629> wider<00:11:03.949> set 00:11:04.939 --> 00:11:04.949 align:start position:0% arbitrarily and of course the wider set 00:11:04.949 --> 00:11:06.939 align:start position:0% arbitrarily and of course the wider set of<00:11:04.980> fault<00:11:05.279> fault<00:11:05.610> types<00:11:05.910> is<00:11:06.059> presenting<00:11:06.569> where 00:11:06.939 --> 00:11:06.949 align:start position:0% of fault fault types is presenting where 00:11:06.949 --> 00:11:13.249 align:start position:0% of fault fault types is presenting where processes<00:11:07.949> can<00:11:08.220> behave<00:11:08.459> up<00:11:08.669> too<00:11:08.879> early<00:11:11.929> so<00:11:12.929> if 00:11:13.249 --> 00:11:13.259 align:start position:0% processes can behave up too early so if 00:11:13.259 --> 00:11:15.439 align:start position:0% processes can behave up too early so if there's<00:11:13.470> anything<00:11:13.799> just<00:11:14.730> to<00:11:14.790> take<00:11:15.029> from<00:11:15.209> this 00:11:15.439 --> 00:11:15.449 align:start position:0% there's anything just to take from this 00:11:15.449 --> 00:11:20.179 align:start position:0% there's anything just to take from this this<00:11:16.139> useful<00:11:16.410> it's<00:11:16.889> that<00:11:17.509> obviously<00:11:18.860> if<00:11:19.860> a 00:11:20.179 --> 00:11:20.189 align:start position:0% this useful it's that obviously if a 00:11:20.189 --> 00:11:21.859 align:start position:0% this useful it's that obviously if a consensus<00:11:20.639> protocol<00:11:21.029> is<00:11:21.149> byzantium<00:11:21.629> fault 00:11:21.859 --> 00:11:21.869 align:start position:0% consensus protocol is byzantium fault 00:11:21.869 --> 00:11:23.989 align:start position:0% consensus protocol is byzantium fault tolerant<00:11:22.319> it's<00:11:22.799> resistant<00:11:23.369> to<00:11:23.459> a<00:11:23.489> far<00:11:23.730> greater 00:11:23.989 --> 00:11:23.999 align:start position:0% tolerant it's resistant to a far greater 00:11:23.999 --> 00:11:28.429 align:start position:0% tolerant it's resistant to a far greater number<00:11:24.989> of<00:11:25.040> faults<00:11:26.059> right<00:11:27.059> I<00:11:27.329> would<00:11:28.079> you<00:11:28.169> folds 00:11:28.429 --> 00:11:28.439 align:start position:0% number of faults right I would you folds 00:11:28.439 --> 00:11:32.509 align:start position:0% number of faults right I would you folds of<00:11:28.559> fact<00:11:28.739> and<00:11:30.679> works<00:11:31.679> within<00:11:31.980> a<00:11:32.100> synchronous 00:11:32.509 --> 00:11:32.519 align:start position:0% of fact and works within a synchronous 00:11:32.519 --> 00:11:35.389 align:start position:0% of fact and works within a synchronous network<00:11:33.529> that's<00:11:34.529> better<00:11:34.769> because<00:11:35.009> it's<00:11:35.279> not 00:11:35.389 --> 00:11:35.399 align:start position:0% network that's better because it's not 00:11:35.399 --> 00:11:39.199 align:start position:0% network that's better because it's not vulnerable<00:11:35.669> to<00:11:36.350> you<00:11:37.350> know<00:11:37.669> correct<00:11:38.669> process 00:11:39.199 --> 00:11:39.209 align:start position:0% vulnerable to you know correct process 00:11:39.209 --> 00:11:40.819 align:start position:0% vulnerable to you know correct process being<00:11:39.480> dido<00:11:39.989> store<00:11:40.230> something<00:11:40.559> or<00:11:40.619> that<00:11:40.739> or 00:11:40.819 --> 00:11:40.829 align:start position:0% being dido store something or that or 00:11:40.829 --> 00:11:44.440 align:start position:0% being dido store something or that or the<00:11:40.860> network<00:11:41.279> just<00:11:41.579> behaving<00:11:41.819> strangely 00:11:44.440 --> 00:11:44.450 align:start position:0% 00:11:44.450 --> 00:11:48.050 align:start position:0% so<00:11:45.740> just<00:11:46.740> to<00:11:46.800> talk<00:11:46.950> about<00:11:47.070> challenges<00:11:47.940> but 00:11:48.050 --> 00:11:48.060 align:start position:0% so just to talk about challenges but 00:11:48.060 --> 00:11:51.140 align:start position:0% so just to talk about challenges but more<00:11:48.240> I<00:11:48.860> think<00:11:49.860> one<00:11:49.980> of<00:11:50.010> the<00:11:50.250> reasons<00:11:50.820> these 00:11:51.140 --> 00:11:51.150 align:start position:0% more I think one of the reasons these 00:11:51.150 --> 00:11:56.090 align:start position:0% more I think one of the reasons these kind<00:11:51.480> of<00:11:52.250> protocols<00:11:53.250> are<00:11:53.370> complex<00:11:53.820> is<00:11:54.770> that<00:11:55.770> in 00:11:56.090 --> 00:11:56.100 align:start position:0% kind of protocols are complex is that in 00:11:56.100 --> 00:11:58.280 align:start position:0% kind of protocols are complex is that in fact<00:11:56.730> of<00:11:56.940> course<00:11:57.000> the<00:11:57.330> state<00:11:57.660> of<00:11:57.690> the<00:11:57.960> network 00:11:58.280 --> 00:11:58.290 align:start position:0% fact of course the state of the network 00:11:58.290 --> 00:12:00.800 align:start position:0% fact of course the state of the network is<00:11:58.920> unknowable<00:11:59.490> and<00:11:59.820> it's<00:12:00.420> easy<00:12:00.570> to<00:12:00.660> forget 00:12:00.800 --> 00:12:00.810 align:start position:0% is unknowable and it's easy to forget 00:12:00.810 --> 00:12:02.510 align:start position:0% is unknowable and it's easy to forget that<00:12:01.170> because<00:12:01.380> you<00:12:01.650> always<00:12:01.770> see<00:12:02.010> a<00:12:02.040> network 00:12:02.510 --> 00:12:02.520 align:start position:0% that because you always see a network 00:12:02.520 --> 00:12:05.300 align:start position:0% that because you always see a network diagram<00:12:03.300> which<00:12:03.870> shows<00:12:03.900> lots<00:12:04.530> of<00:12:04.740> connected 00:12:05.300 --> 00:12:05.310 align:start position:0% diagram which shows lots of connected 00:12:05.310 --> 00:12:06.860 align:start position:0% diagram which shows lots of connected nodes<00:12:05.520> and<00:12:05.850> some<00:12:06.060> of<00:12:06.150> them<00:12:06.240> are<00:12:06.330> correct<00:12:06.690> and 00:12:06.860 --> 00:12:06.870 align:start position:0% nodes and some of them are correct and 00:12:06.870 --> 00:12:08.240 align:start position:0% nodes and some of them are correct and some<00:12:07.080> of<00:12:07.170> them<00:12:07.260> are<00:12:07.320> faulty<00:12:07.680> but<00:12:07.920> it<00:12:08.010> but<00:12:08.160> in 00:12:08.240 --> 00:12:08.250 align:start position:0% some of them are faulty but it but in 00:12:08.250 --> 00:12:11.060 align:start position:0% some of them are faulty but it but in actual<00:12:08.550> fact<00:12:09.410> nobody<00:12:10.410> can<00:12:10.590> know<00:12:10.620> what<00:12:10.950> the 00:12:11.060 --> 00:12:11.070 align:start position:0% actual fact nobody can know what the 00:12:11.070 --> 00:12:13.370 align:start position:0% actual fact nobody can know what the state<00:12:11.280> of<00:12:11.310> the<00:12:11.490> network<00:12:11.790> is<00:12:12.030> right<00:12:12.960> you<00:12:13.200> can 00:12:13.370 --> 00:12:13.380 align:start position:0% state of the network is right you can 00:12:13.380 --> 00:12:15.170 align:start position:0% state of the network is right you can only<00:12:13.500> make<00:12:13.770> inferences<00:12:14.520> about<00:12:14.550> the<00:12:14.970> current 00:12:15.170 --> 00:12:15.180 align:start position:0% only make inferences about the current 00:12:15.180 --> 00:12:17.720 align:start position:0% only make inferences about the current state<00:12:15.360> of<00:12:15.480> the<00:12:15.660> network<00:12:16.050> based<00:12:17.010> upon<00:12:17.400> the 00:12:17.720 --> 00:12:17.730 align:start position:0% state of the network based upon the 00:12:17.730 --> 00:12:20.390 align:start position:0% state of the network based upon the messages<00:12:18.150> you<00:12:18.180> receive<00:12:18.330> and<00:12:18.930> that's<00:12:19.920> equally 00:12:20.390 --> 00:12:20.400 align:start position:0% messages you receive and that's equally 00:12:20.400 --> 00:12:21.500 align:start position:0% messages you receive and that's equally true<00:12:20.640> actually<00:12:20.790> for<00:12:21.060> these<00:12:21.180> kind<00:12:21.450> of 00:12:21.500 --> 00:12:21.510 align:start position:0% true actually for these kind of 00:12:21.510 --> 00:12:23.060 align:start position:0% true actually for these kind of consensus<00:12:21.810> protocols<00:12:22.380> as<00:12:22.590> it<00:12:22.680> is<00:12:22.800> from 00:12:23.060 --> 00:12:23.070 align:start position:0% consensus protocols as it is from 00:12:23.070 --> 00:12:26.000 align:start position:0% consensus protocols as it is from blockchain<00:12:24.050> based<00:12:25.050> consensus<00:12:25.590> protocols 00:12:26.000 --> 00:12:26.010 align:start position:0% blockchain based consensus protocols 00:12:26.010 --> 00:12:28.370 align:start position:0% blockchain based consensus protocols you've<00:12:26.670> got<00:12:26.820> no<00:12:27.000> way<00:12:27.180> of<00:12:27.210> knowing<00:12:27.330> what<00:12:27.870> be<00:12:28.080> the 00:12:28.370 --> 00:12:28.380 align:start position:0% you've got no way of knowing what be the 00:12:28.380 --> 00:12:29.960 align:start position:0% you've got no way of knowing what be the overall<00:12:28.740> state<00:12:29.010> of<00:12:29.160> the<00:12:29.250> network<00:12:29.580> is<00:12:29.700> you<00:12:29.820> can 00:12:29.960 --> 00:12:29.970 align:start position:0% overall state of the network is you can 00:12:29.970 --> 00:12:31.700 align:start position:0% overall state of the network is you can only<00:12:30.000> make<00:12:30.210> inferences<00:12:30.780> about<00:12:30.810> it<00:12:31.200> based<00:12:31.500> upon 00:12:31.700 --> 00:12:31.710 align:start position:0% only make inferences about it based upon 00:12:31.710 --> 00:12:34.250 align:start position:0% only make inferences about it based upon the<00:12:32.240> messages<00:12:33.240> you<00:12:33.360> receive<00:12:33.390> now<00:12:33.930> you<00:12:33.990> can 00:12:34.250 --> 00:12:34.260 align:start position:0% the messages you receive now you can 00:12:34.260 --> 00:12:38.570 align:start position:0% the messages you receive now you can send<00:12:35.220> messages<00:12:35.430> out<00:12:35.850> to<00:12:35.880> ask<00:12:37.130> questions<00:12:38.130> and 00:12:38.570 --> 00:12:38.580 align:start position:0% send messages out to ask questions and 00:12:38.580 --> 00:12:41.990 align:start position:0% send messages out to ask questions and you<00:12:38.640> may<00:12:38.820> or<00:12:38.940> may<00:12:39.120> not<00:12:39.150> get<00:12:39.770> answers<00:12:40.910> but<00:12:41.910> you 00:12:41.990 --> 00:12:42.000 align:start position:0% you may or may not get answers but you 00:12:42.000 --> 00:12:43.490 align:start position:0% you may or may not get answers but you can<00:12:42.120> only<00:12:42.150> make<00:12:42.390> imprint<00:12:42.780> inferences<00:12:43.350> the 00:12:43.490 --> 00:12:43.500 align:start position:0% can only make imprint inferences the 00:12:43.500 --> 00:12:47.780 align:start position:0% can only make imprint inferences the network<00:12:43.740> is<00:12:43.830> a<00:12:43.890> black<00:12:44.070> box<00:12:45.920> another<00:12:46.920> big 00:12:47.780 --> 00:12:47.790 align:start position:0% network is a black box another big 00:12:47.790 --> 00:12:49.430 align:start position:0% network is a black box another big challenge<00:12:48.000> is<00:12:48.360> equivocation<00:12:49.050> by<00:12:49.200> faulty 00:12:49.430 --> 00:12:49.440 align:start position:0% challenge is equivocation by faulty 00:12:49.440 --> 00:12:52.000 align:start position:0% challenge is equivocation by faulty nodes<00:12:49.770> and<00:12:50.550> again<00:12:50.880> this<00:12:51.060> applies<00:12:51.390> to 00:12:52.000 --> 00:12:52.010 align:start position:0% nodes and again this applies to 00:12:52.010 --> 00:12:54.470 align:start position:0% nodes and again this applies to protocols<00:12:53.010> like<00:12:53.070> Casper<00:12:53.670> Ola<00:12:53.880> this<00:12:54.030> is<00:12:54.180> again 00:12:54.470 --> 00:12:54.480 align:start position:0% protocols like Casper Ola this is again 00:12:54.480 --> 00:12:59.170 align:start position:0% protocols like Casper Ola this is again as<00:12:54.720> assuming<00:12:55.200> a<00:12:56.930> traditional<00:12:57.930> consensus 00:12:59.170 --> 00:12:59.180 align:start position:0% as assuming a traditional consensus 00:12:59.180 --> 00:13:02.690 align:start position:0% as assuming a traditional consensus protocol<00:13:00.180> and<00:13:01.190> equivocation<00:13:02.190> simply<00:13:02.520> means 00:13:02.690 --> 00:13:02.700 align:start position:0% protocol and equivocation simply means 00:13:02.700 --> 00:13:04.790 align:start position:0% protocol and equivocation simply means that<00:13:02.790> faulty<00:13:03.270> nodes<00:13:03.480> can<00:13:03.870> send<00:13:04.260> two<00:13:04.500> different 00:13:04.790 --> 00:13:04.800 align:start position:0% that faulty nodes can send two different 00:13:04.800 --> 00:13:07.010 align:start position:0% that faulty nodes can send two different versions<00:13:05.250> of<00:13:05.520> a<00:13:06.060> message<00:13:06.300> when<00:13:06.660> there<00:13:06.780> any<00:13:06.870> men 00:13:07.010 --> 00:13:07.020 align:start position:0% versions of a message when there any men 00:13:07.020 --> 00:13:09.220 align:start position:0% versions of a message when there any men or<00:13:07.170> men<00:13:07.440> ascend<00:13:07.740> one<00:13:08.010> so<00:13:08.340> in<00:13:08.430> this<00:13:08.550> case 00:13:09.220 --> 00:13:09.230 align:start position:0% or men ascend one so in this case 00:13:09.230 --> 00:13:13.730 align:start position:0% or men ascend one so in this case process<00:13:10.230> one<00:13:10.440> is<00:13:10.710> is<00:13:11.600> faulty<00:13:12.600> and<00:13:12.810> it's 00:13:13.730 --> 00:13:13.740 align:start position:0% process one is is faulty and it's 00:13:13.740 --> 00:13:17.180 align:start position:0% process one is is faulty and it's telling<00:13:14.120> process<00:13:15.120> to<00:13:15.360> that<00:13:15.630> it's<00:13:15.780> voting<00:13:16.190> ABC 00:13:17.180 --> 00:13:17.190 align:start position:0% telling process to that it's voting ABC 00:13:17.190 --> 00:13:18.950 align:start position:0% telling process to that it's voting ABC and<00:13:17.430> it's<00:13:17.550> telling<00:13:17.910> process<00:13:18.420> through<00:13:18.720> that 00:13:18.950 --> 00:13:18.960 align:start position:0% and it's telling process through that 00:13:18.960 --> 00:13:23.510 align:start position:0% and it's telling process through that it's<00:13:19.110> voting<00:13:19.530> NO<00:13:20.220> and<00:13:22.370> equivocation<00:13:23.370> is<00:13:23.490> a 00:13:23.510 --> 00:13:23.520 align:start position:0% it's voting NO and equivocation is a 00:13:23.520 --> 00:13:26.800 align:start position:0% it's voting NO and equivocation is a surprisingly<00:13:24.240> powerful<00:13:24.630> tool<00:13:25.140> for 00:13:26.800 --> 00:13:26.810 align:start position:0% surprisingly powerful tool for 00:13:26.810 --> 00:13:29.690 align:start position:0% surprisingly powerful tool for anniversary<00:13:27.810> to<00:13:27.960> use<00:13:28.200> can<00:13:28.860> kredel<00:13:29.340> kinds<00:13:29.610> of 00:13:29.690 --> 00:13:29.700 align:start position:0% anniversary to use can kredel kinds of 00:13:29.700 --> 00:13:35.630 align:start position:0% anniversary to use can kredel kinds of problems<00:13:29.850> and<00:13:32.600> as<00:13:33.600> a<00:13:33.630> result<00:13:33.870> that<00:13:34.520> comes<00:13:35.520> from 00:13:35.630 --> 00:13:35.640 align:start position:0% problems and as a result that comes from 00:13:35.640 --> 00:13:39.290 align:start position:0% problems and as a result that comes from this<00:13:35.850> which<00:13:36.120> is<00:13:36.300> that<00:13:36.500> typically<00:13:37.500> to<00:13:38.300> reach 00:13:39.290 --> 00:13:39.300 align:start position:0% this which is that typically to reach 00:13:39.300 --> 00:13:41.510 align:start position:0% this which is that typically to reach consensus<00:13:39.650> when<00:13:40.650> you<00:13:40.770> receive<00:13:40.920> a<00:13:41.220> message 00:13:41.510 --> 00:13:41.520 align:start position:0% consensus when you receive a message 00:13:41.520 --> 00:13:44.300 align:start position:0% consensus when you receive a message from<00:13:41.730> a<00:13:42.120> process<00:13:42.720> you<00:13:43.320> need<00:13:43.500> to<00:13:43.590> echo<00:13:43.980> it<00:13:44.130> to 00:13:44.300 --> 00:13:44.310 align:start position:0% from a process you need to echo it to 00:13:44.310 --> 00:13:46.490 align:start position:0% from a process you need to echo it to all<00:13:44.430> the<00:13:44.550> other<00:13:44.670> processes<00:13:45.360> to<00:13:45.990> make<00:13:46.170> sure 00:13:46.490 --> 00:13:46.500 align:start position:0% all the other processes to make sure 00:13:46.500 --> 00:13:50.300 align:start position:0% all the other processes to make sure that<00:13:47.280> that<00:13:48.320> it<00:13:49.320> hasn't<00:13:49.470> been<00:13:49.650> equivocating 00:13:50.300 --> 00:13:50.310 align:start position:0% that that it hasn't been equivocating 00:13:50.310 --> 00:13:53.990 align:start position:0% that that it hasn't been equivocating and<00:13:51.050> this<00:13:52.050> kind<00:13:52.260> of<00:13:52.380> leads<00:13:52.800> to<00:13:53.000> quadratic 00:13:53.990 --> 00:13:54.000 align:start position:0% and this kind of leads to quadratic 00:13:54.000 --> 00:13:56.160 align:start position:0% and this kind of leads to quadratic message<00:13:54.510> complexity<00:13:55.110> which<00:13:55.260> basically<00:13:55.560> means 00:13:56.160 --> 00:13:56.170 align:start position:0% message complexity which basically means 00:13:56.170 --> 00:13:58.790 align:start position:0% message complexity which basically means that<00:13:56.260> as<00:13:56.440> the<00:13:57.220> number<00:13:57.490> of<00:13:57.579> processes 00:13:58.790 --> 00:13:58.800 align:start position:0% that as the number of processes 00:13:58.800 --> 00:14:02.370 align:start position:0% that as the number of processes cooperating<00:13:59.800> in<00:13:59.980> consensus<00:14:00.820> increases<00:14:01.630> the 00:14:02.370 --> 00:14:02.380 align:start position:0% cooperating in consensus increases the 00:14:02.380 --> 00:14:05.009 align:start position:0% cooperating in consensus increases the number<00:14:02.560> of<00:14:02.709> messages<00:14:03.070> they<00:14:03.880> send<00:14:04.269> increases 00:14:05.009 --> 00:14:05.019 align:start position:0% number of messages they send increases 00:14:05.019 --> 00:14:06.240 align:start position:0% number of messages they send increases with<00:14:05.230> the<00:14:05.260> square<00:14:05.709> of<00:14:05.889> the<00:14:05.980> number<00:14:06.010> of 00:14:06.240 --> 00:14:06.250 align:start position:0% with the square of the number of 00:14:06.250 --> 00:14:08.699 align:start position:0% with the square of the number of processes<00:14:06.730> and<00:14:07.110> that's<00:14:08.110> the<00:14:08.380> reason<00:14:08.680> why 00:14:08.699 --> 00:14:08.709 align:start position:0% processes and that's the reason why 00:14:08.709 --> 00:14:10.800 align:start position:0% processes and that's the reason why Satoshi<00:14:09.220> creatives<00:14:09.790> the<00:14:10.420> proof<00:14:10.570> of<00:14:10.690> work 00:14:10.800 --> 00:14:10.810 align:start position:0% Satoshi creatives the proof of work 00:14:10.810 --> 00:14:12.860 align:start position:0% Satoshi creatives the proof of work blockchain<00:14:11.139> because<00:14:11.860> it<00:14:12.010> doesn't<00:14:12.339> have<00:14:12.370> this 00:14:12.860 --> 00:14:12.870 align:start position:0% blockchain because it doesn't have this 00:14:12.870 --> 00:14:16.259 align:start position:0% blockchain because it doesn't have this problem<00:14:13.870> ok<00:14:14.709> has<00:14:15.010> a<00:14:15.040> different<00:14:15.430> works<00:14:16.060> in<00:14:16.240> a 00:14:16.259 --> 00:14:16.269 align:start position:0% problem ok has a different works in a 00:14:16.269 --> 00:14:19.139 align:start position:0% problem ok has a different works in a different<00:14:16.389> way<00:14:17.010> that<00:14:18.010> people<00:14:18.550> try<00:14:18.880> and<00:14:19.000> solve 00:14:19.139 --> 00:14:19.149 align:start position:0% different way that people try and solve 00:14:19.149 --> 00:14:20.699 align:start position:0% different way that people try and solve puzzles<00:14:19.600> and<00:14:19.750> whoever<00:14:19.990> solves<00:14:20.410> the<00:14:20.560> puzzle 00:14:20.699 --> 00:14:20.709 align:start position:0% puzzles and whoever solves the puzzle 00:14:20.709 --> 00:14:23.569 align:start position:0% puzzles and whoever solves the puzzle gets<00:14:21.160> to<00:14:21.310> cast<00:14:21.519> a<00:14:21.699> deciding<00:14:22.209> vote<00:14:22.449> right<00:14:22.810> and 00:14:23.569 --> 00:14:23.579 align:start position:0% gets to cast a deciding vote right and 00:14:23.579 --> 00:14:26.100 align:start position:0% gets to cast a deciding vote right and you<00:14:24.579> don't<00:14:24.730> get<00:14:24.820> strong<00:14:25.089> consistency<00:14:25.570> you<00:14:25.779> get 00:14:26.100 --> 00:14:26.110 align:start position:0% you don't get strong consistency you get 00:14:26.110 --> 00:14:28.470 align:start position:0% you don't get strong consistency you get a<00:14:26.139> sort<00:14:26.320> of<00:14:26.350> it<00:14:26.790> eventual<00:14:27.790> consistency<00:14:27.910> as 00:14:28.470 --> 00:14:28.480 align:start position:0% a sort of it eventual consistency as 00:14:28.480 --> 00:14:34.170 align:start position:0% a sort of it eventual consistency as them<00:14:28.630> as<00:14:28.810> the<00:14:31.230> chain<00:14:32.230> gets<00:14:32.380> longer<00:14:32.800> and<00:14:33.180> block 00:14:34.170 --> 00:14:34.180 align:start position:0% them as the chain gets longer and block 00:14:34.180 --> 00:14:35.579 align:start position:0% them as the chain gets longer and block gets<00:14:34.389> buried<00:14:34.600> deeper<00:14:34.930> and<00:14:35.050> deeper<00:14:35.170> it<00:14:35.470> gets 00:14:35.579 --> 00:14:35.589 align:start position:0% gets buried deeper and deeper it gets 00:14:35.589 --> 00:14:39.290 align:start position:0% gets buried deeper and deeper it gets more<00:14:36.010> and<00:14:36.070> more<00:14:36.130> likely<00:14:36.550> to<00:14:36.639> be<00:14:36.730> permanent<00:14:38.220> so 00:14:39.290 --> 00:14:39.300 align:start position:0% more and more likely to be permanent so 00:14:39.300 --> 00:14:41.930 align:start position:0% more and more likely to be permanent so that's<00:14:40.300> the<00:14:40.360> limitation<00:14:40.750> of<00:14:40.990> this<00:14:41.529> kind<00:14:41.740> of 00:14:41.930 --> 00:14:41.940 align:start position:0% that's the limitation of this kind of 00:14:41.940 --> 00:14:44.670 align:start position:0% that's the limitation of this kind of protocols<00:14:42.990> the<00:14:43.990> number<00:14:44.260> of<00:14:44.320> messages<00:14:44.529> they 00:14:44.670 --> 00:14:44.680 align:start position:0% protocols the number of messages they 00:14:44.680 --> 00:14:46.079 align:start position:0% protocols the number of messages they have<00:14:44.800> to<00:14:44.889> pass<00:14:45.040> increases<00:14:45.519> with<00:14:45.699> the<00:14:45.730> the 00:14:46.079 --> 00:14:46.089 align:start position:0% have to pass increases with the the 00:14:46.089 --> 00:14:49.740 align:start position:0% have to pass increases with the the square<00:14:46.540> of<00:14:47.160> the<00:14:48.160> number<00:14:48.970> of<00:14:49.329> processes 00:14:49.740 --> 00:14:49.750 align:start position:0% square of the number of processes 00:14:49.750 --> 00:14:51.480 align:start position:0% square of the number of processes involved<00:14:50.290> and<00:14:50.410> so<00:14:50.529> consequently<00:14:50.709> they<00:14:51.250> tend 00:14:51.480 --> 00:14:51.490 align:start position:0% involved and so consequently they tend 00:14:51.490 --> 00:14:53.280 align:start position:0% involved and so consequently they tend to<00:14:51.550> be<00:14:51.639> used<00:14:51.850> within<00:14:52.000> a<00:14:52.149> larger<00:14:52.660> protocol<00:14:53.110> as 00:14:53.280 --> 00:14:53.290 align:start position:0% to be used within a larger protocol as 00:14:53.290 --> 00:14:56.639 align:start position:0% to be used within a larger protocol as we<00:14:53.410> look<00:14:53.560> sat<00:14:53.740> at<00:14:53.889> the<00:14:53.949> beginning<00:14:55.410> so<00:14:56.410> here's 00:14:56.639 --> 00:14:56.649 align:start position:0% we look sat at the beginning so here's 00:14:56.649 --> 00:14:58.590 align:start position:0% we look sat at the beginning so here's another<00:14:56.800> challenge<00:14:57.279> this<00:14:57.459> is<00:14:57.670> network 00:14:58.590 --> 00:14:58.600 align:start position:0% another challenge this is network 00:14:58.600 --> 00:15:00.920 align:start position:0% another challenge this is network asynchrony<00:14:59.320> and<00:14:59.440> this<00:14:59.560> is<00:14:59.709> actually<00:14:59.920> probably 00:15:00.920 --> 00:15:00.930 align:start position:0% asynchrony and this is actually probably 00:15:00.930 --> 00:15:03.530 align:start position:0% asynchrony and this is actually probably the<00:15:01.930> most<00:15:02.079> profound<00:15:02.589> challenge<00:15:03.040> of<00:15:03.160> thing 00:15:03.530 --> 00:15:03.540 align:start position:0% the most profound challenge of thing 00:15:03.540 --> 00:15:06.449 align:start position:0% the most profound challenge of thing which<00:15:04.540> is<00:15:04.600> there's<00:15:05.230> no<00:15:05.410> way<00:15:05.620> of<00:15:05.740> knowing<00:15:05.769> if 00:15:06.449 --> 00:15:06.459 align:start position:0% which is there's no way of knowing if 00:15:06.459 --> 00:15:08.310 align:start position:0% which is there's no way of knowing if the<00:15:06.880> network<00:15:07.149> can<00:15:07.360> pave<00:15:07.600> it<00:15:07.750> in<00:15:07.839> a<00:15:07.930> synchronous 00:15:08.310 --> 00:15:08.320 align:start position:0% the network can pave it in a synchronous 00:15:08.320 --> 00:15:10.800 align:start position:0% the network can pave it in a synchronous way<00:15:08.560> why<00:15:09.519> you<00:15:09.579> haven't<00:15:10.149> received<00:15:10.510> a<00:15:10.630> message 00:15:10.800 --> 00:15:10.810 align:start position:0% way why you haven't received a message 00:15:10.810 --> 00:15:13.829 align:start position:0% way why you haven't received a message so<00:15:11.589> in<00:15:11.680> this<00:15:11.800> case<00:15:12.010> he<00:15:12.790> too<00:15:13.060> is<00:15:13.089> expecting<00:15:13.779> a 00:15:13.829 --> 00:15:13.839 align:start position:0% so in this case he too is expecting a 00:15:13.839 --> 00:15:18.660 align:start position:0% so in this case he too is expecting a message<00:15:14.170> from<00:15:14.560> p1<00:15:15.089> ok<00:15:16.089> and<00:15:17.370> it<00:15:18.370> hasn't 00:15:18.660 --> 00:15:18.670 align:start position:0% message from p1 ok and it hasn't 00:15:18.670 --> 00:15:24.240 align:start position:0% message from p1 ok and it hasn't received<00:15:18.880> a<00:15:19.060> message<00:15:19.209> from<00:15:19.420> p1<00:15:20.040> ok<00:15:21.240> so<00:15:23.130> what<00:15:24.130> is 00:15:24.240 --> 00:15:24.250 align:start position:0% received a message from p1 ok so what is 00:15:24.250 --> 00:15:26.490 align:start position:0% received a message from p1 ok so what is p2<00:15:24.730> mother<00:15:24.970> think<00:15:25.240> does<00:15:25.690> it<00:15:25.810> continue<00:15:26.140> waiting 00:15:26.490 --> 00:15:26.500 align:start position:0% p2 mother think does it continue waiting 00:15:26.500 --> 00:15:32.400 align:start position:0% p2 mother think does it continue waiting for<00:15:26.860> the<00:15:26.920> message<00:15:27.220> from<00:15:27.370> p1<00:15:30.089> so<00:15:31.350> there's<00:15:32.350> a 00:15:32.400 --> 00:15:32.410 align:start position:0% for the message from p1 so there's a 00:15:32.410 --> 00:15:34.740 align:start position:0% for the message from p1 so there's a system<00:15:33.100> called<00:15:33.459> ripple<00:15:33.790> she<00:15:34.240> probably<00:15:34.570> all 00:15:34.740 --> 00:15:34.750 align:start position:0% system called ripple she probably all 00:15:34.750 --> 00:15:37.889 align:start position:0% system called ripple she probably all aware<00:15:35.440> of<00:15:35.589> and<00:15:35.980> they<00:15:36.970> had<00:15:37.149> a<00:15:37.180> consensus 00:15:37.889 --> 00:15:37.899 align:start position:0% aware of and they had a consensus 00:15:37.899 --> 00:15:40.680 align:start position:0% aware of and they had a consensus protocol<00:15:38.550> which<00:15:39.550> didn't<00:15:39.880> handle<00:15:40.180> a<00:15:40.269> synchrony 00:15:40.680 --> 00:15:40.690 align:start position:0% protocol which didn't handle a synchrony 00:15:40.690 --> 00:15:43.230 align:start position:0% protocol which didn't handle a synchrony correctly<00:15:41.199> and<00:15:41.410> it<00:15:41.949> was<00:15:42.069> adopted<00:15:42.339> by<00:15:42.760> another 00:15:43.230 --> 00:15:43.240 align:start position:0% correctly and it was adopted by another 00:15:43.240 --> 00:15:46.769 align:start position:0% correctly and it was adopted by another cryptic<00:15:43.899> article<00:15:44.380> Stella<00:15:44.769> and<00:15:45.630> it<00:15:46.630> was 00:15:46.769 --> 00:15:46.779 align:start position:0% cryptic article Stella and it was 00:15:46.779 --> 00:15:48.180 align:start position:0% cryptic article Stella and it was absolutely<00:15:47.199> plain<00:15:47.529> from<00:15:47.860> the<00:15:47.949> way<00:15:48.040> they 00:15:48.180 --> 00:15:48.190 align:start position:0% absolutely plain from the way they 00:15:48.190 --> 00:15:50.280 align:start position:0% absolutely plain from the way they described<00:15:48.610> the<00:15:48.760> the<00:15:49.449> protocol<00:15:49.870> that<00:15:50.050> I<00:15:50.079> had 00:15:50.280 --> 00:15:50.290 align:start position:0% described the the protocol that I had 00:15:50.290 --> 00:15:52.199 align:start position:0% described the the protocol that I had this<00:15:50.529> issue<00:15:51.040> of<00:15:51.339> the<00:15:51.430> synchrony<00:15:51.819> that<00:15:52.029> it 00:15:52.199 --> 00:15:52.209 align:start position:0% this issue of the synchrony that it 00:15:52.209 --> 00:15:54.030 align:start position:0% this issue of the synchrony that it would<00:15:52.360> just<00:15:52.540> make<00:15:52.750> an<00:15:52.990> assumption<00:15:53.649> that<00:15:53.829> it 00:15:54.030 --> 00:15:54.040 align:start position:0% would just make an assumption that it 00:15:54.040 --> 00:15:58.500 align:start position:0% would just make an assumption that it hadn't<00:15:54.339> got<00:15:55.240> a<00:15:55.860> message<00:15:56.860> because<00:15:57.370> the<00:15:57.510> sender 00:15:58.500 --> 00:15:58.510 align:start position:0% hadn't got a message because the sender 00:15:58.510 --> 00:16:00.540 align:start position:0% hadn't got a message because the sender had<00:15:58.600> failed<00:15:58.899> ok<00:15:59.440> and<00:15:59.620> as<00:15:59.680> a<00:15:59.709> consequence<00:16:00.279> they 00:16:00.540 --> 00:16:00.550 align:start position:0% had failed ok and as a consequence they 00:16:00.550 --> 00:16:03.569 align:start position:0% had failed ok and as a consequence they had<00:16:00.730> a<00:16:00.760> day<00:16:01.300> out<00:16:01.329> of<00:16:01.449> four<00:16:01.920> so<00:16:02.920> it's<00:16:03.160> very<00:16:03.310> easy 00:16:03.569 --> 00:16:03.579 align:start position:0% had a day out of four so it's very easy 00:16:03.579 --> 00:16:06.009 align:start position:0% had a day out of four so it's very easy to<00:16:04.350> just<00:16:05.350> imagine<00:16:05.800> what 00:16:06.009 --> 00:16:06.019 align:start position:0% to just imagine what 00:16:06.019 --> 00:16:08.079 align:start position:0% to just imagine what haven't<00:16:06.769> received<00:16:07.040> a<00:16:07.129> message<00:16:07.279> the<00:16:07.730> sending 00:16:08.079 --> 00:16:08.089 align:start position:0% haven't received a message the sending 00:16:08.089 --> 00:16:09.429 align:start position:0% haven't received a message the sending us<00:16:08.209> to<00:16:08.329> fails<00:16:08.600> therefore<00:16:09.170> I'm<00:16:09.259> going<00:16:09.290> to 00:16:09.429 --> 00:16:09.439 align:start position:0% us to fails therefore I'm going to 00:16:09.439 --> 00:16:11.460 align:start position:0% us to fails therefore I'm going to proceed<00:16:09.739> with<00:16:09.949> the<00:16:10.040> messages<00:16:10.339> i<00:16:10.489> have<00:16:10.730> and 00:16:11.460 --> 00:16:11.470 align:start position:0% proceed with the messages i have and 00:16:11.470 --> 00:16:13.840 align:start position:0% proceed with the messages i have and assume<00:16:12.470> that<00:16:12.709> some<00:16:13.249> some<00:16:13.519> part<00:16:13.730> of<00:16:13.790> the 00:16:13.840 --> 00:16:13.850 align:start position:0% assume that some some part of the 00:16:13.850 --> 00:16:16.359 align:start position:0% assume that some some part of the network's<00:16:14.149> faulty<00:16:14.449> but<00:16:14.629> it<00:16:15.189> can<00:16:16.189> lead<00:16:16.339> to 00:16:16.359 --> 00:16:16.369 align:start position:0% network's faulty but it can lead to 00:16:16.369 --> 00:16:20.679 align:start position:0% network's faulty but it can lead to problems<00:16:18.369> so<00:16:19.369> of<00:16:19.579> course<00:16:19.639> you<00:16:20.209> know<00:16:20.389> an 00:16:20.679 --> 00:16:20.689 align:start position:0% problems so of course you know an 00:16:20.689 --> 00:16:24.660 align:start position:0% problems so of course you know an adversary<00:16:21.879> realizing<00:16:22.879> that<00:16:23.209> the<00:16:23.600> receiver 00:16:24.660 --> 00:16:24.670 align:start position:0% adversary realizing that the receiver 00:16:24.670 --> 00:16:27.069 align:start position:0% adversary realizing that the receiver doesn't<00:16:25.670> know<00:16:25.850> what<00:16:25.999> to<00:16:26.029> do<00:16:26.269> can<00:16:26.569> use<00:16:26.749> this<00:16:26.899> as 00:16:27.069 --> 00:16:27.079 align:start position:0% doesn't know what to do can use this as 00:16:27.079 --> 00:16:28.780 align:start position:0% doesn't know what to do can use this as a<00:16:27.110> tool<00:16:27.410> you<00:16:27.589> can<00:16:27.739> decide<00:16:28.189> to<00:16:28.399> withhold 00:16:28.780 --> 00:16:28.790 align:start position:0% a tool you can decide to withhold 00:16:28.790 --> 00:16:34.229 align:start position:0% a tool you can decide to withhold messages<00:16:29.329> right<00:16:30.019> and<00:16:31.629> there<00:16:32.629> is<00:16:32.749> a<00:16:32.779> kind<00:16:33.079> of 00:16:34.229 --> 00:16:34.239 align:start position:0% messages right and there is a kind of 00:16:34.239 --> 00:16:38.280 align:start position:0% messages right and there is a kind of prefer<00:16:35.239> issue<00:16:35.449> that<00:16:36.079> comes<00:16:36.259> from<00:16:36.470> that<00:16:36.559> so 00:16:38.280 --> 00:16:38.290 align:start position:0% prefer issue that comes from that so 00:16:38.290 --> 00:16:40.780 align:start position:0% prefer issue that comes from that so what<00:16:39.290> is<00:16:39.410> the<00:16:39.559> you<00:16:39.949> know<00:16:40.129> the<00:16:40.249> maximum<00:16:40.759> number 00:16:40.780 --> 00:16:40.790 align:start position:0% what is the you know the maximum number 00:16:40.790 --> 00:16:42.970 align:start position:0% what is the you know the maximum number of<00:16:41.179> faulty<00:16:41.689> processes<00:16:42.290> that<00:16:42.470> these<00:16:42.619> kind<00:16:42.889> of 00:16:42.970 --> 00:16:42.980 align:start position:0% of faulty processes that these kind of 00:16:42.980 --> 00:16:48.030 align:start position:0% of faulty processes that these kind of consensus<00:16:43.309> protocols<00:16:44.110> can<00:16:45.110> handle<00:16:45.559> and 00:16:48.030 --> 00:16:48.040 align:start position:0% 00:16:48.040 --> 00:16:50.470 align:start position:0% there's<00:16:49.040> no<00:16:49.160> easy<00:16:49.549> way<00:16:49.759> to<00:16:49.910> think<00:16:50.179> about<00:16:50.329> it 00:16:50.470 --> 00:16:50.480 align:start position:0% there's no easy way to think about it 00:16:50.480 --> 00:16:54.069 align:start position:0% there's no easy way to think about it perhaps<00:16:50.899> this<00:16:51.079> is<00:16:51.199> the<00:16:51.230> easiest<00:16:52.929> there's<00:16:53.929> a 00:16:54.069 --> 00:16:54.079 align:start position:0% perhaps this is the easiest there's a 00:16:54.079 --> 00:16:56.410 align:start position:0% perhaps this is the easiest there's a thing<00:16:54.290> called<00:16:54.319> the<00:16:54.499> Byzantine<00:16:55.189> poorer<00:16:55.639> and<00:16:56.059> a 00:16:56.410 --> 00:16:56.420 align:start position:0% thing called the Byzantine poorer and a 00:16:56.420 --> 00:17:00.850 align:start position:0% thing called the Byzantine poorer and a Byzantium<00:16:56.929> quorum<00:16:57.379> is<00:16:57.529> a<00:16:58.239> subset<00:16:59.239> of<00:16:59.299> nodes<00:16:59.860> so 00:17:00.850 --> 00:17:00.860 align:start position:0% Byzantium quorum is a subset of nodes so 00:17:00.860 --> 00:17:04.559 align:start position:0% Byzantium quorum is a subset of nodes so chosen<00:17:01.489> that<00:17:01.689> if<00:17:02.689> two<00:17:02.989> different<00:17:03.319> forums<00:17:03.769> are 00:17:04.559 --> 00:17:04.569 align:start position:0% chosen that if two different forums are 00:17:04.569 --> 00:17:07.029 align:start position:0% chosen that if two different forums are selected<00:17:05.569> they<00:17:05.720> will<00:17:05.839> always<00:17:05.990> intersect<00:17:06.529> in 00:17:07.029 --> 00:17:07.039 align:start position:0% selected they will always intersect in 00:17:07.039 --> 00:17:12.579 align:start position:0% selected they will always intersect in at<00:17:07.189> least<00:17:07.399> one<00:17:09.399> correct<00:17:10.399> node<00:17:10.760> and<00:17:11.350> this<00:17:12.350> means 00:17:12.579 --> 00:17:12.589 align:start position:0% at least one correct node and this means 00:17:12.589 --> 00:17:15.669 align:start position:0% at least one correct node and this means that<00:17:12.679> you<00:17:12.919> can<00:17:13.250> chain<00:17:14.319> operations<00:17:15.319> together 00:17:15.669 --> 00:17:15.679 align:start position:0% that you can chain operations together 00:17:15.679 --> 00:17:19.260 align:start position:0% that you can chain operations together and<00:17:16.130> produce<00:17:16.339> some<00:17:17.049> kind<00:17:18.049> of<00:17:18.110> result<00:17:18.559> or 00:17:19.260 --> 00:17:19.270 align:start position:0% and produce some kind of result or 00:17:19.270 --> 00:17:22.449 align:start position:0% and produce some kind of result or inference<00:17:20.270> and<00:17:20.480> so<00:17:21.470> we<00:17:21.589> can<00:17:21.740> see<00:17:21.919> here<00:17:22.100> there's 00:17:22.449 --> 00:17:22.459 align:start position:0% inference and so we can see here there's 00:17:22.459 --> 00:17:25.840 align:start position:0% inference and so we can see here there's seven<00:17:22.730> here<00:17:22.850> are<00:17:22.939> seven<00:17:23.240> notes<00:17:23.449> and<00:17:24.579> these<00:17:25.579> two 00:17:25.840 --> 00:17:25.850 align:start position:0% seven here are seven notes and these two 00:17:25.850 --> 00:17:29.260 align:start position:0% seven here are seven notes and these two quorums<00:17:26.439> intersect<00:17:27.730> there<00:17:28.730> are<00:17:28.789> two<00:17:28.940> forums 00:17:29.260 --> 00:17:29.270 align:start position:0% quorums intersect there are two forums 00:17:29.270 --> 00:17:33.070 align:start position:0% quorums intersect there are two forums here<00:17:29.539> of<00:17:30.429> five<00:17:31.429> nodes<00:17:31.700> and<00:17:32.389> you<00:17:32.630> can<00:17:32.779> see<00:17:32.929> they 00:17:33.070 --> 00:17:33.080 align:start position:0% here of five nodes and you can see they 00:17:33.080 --> 00:17:35.710 align:start position:0% here of five nodes and you can see they both<00:17:33.260> intersect<00:17:33.799> in<00:17:34.100> one<00:17:34.820> node<00:17:35.090> even<00:17:35.570> though 00:17:35.710 --> 00:17:35.720 align:start position:0% both intersect in one node even though 00:17:35.720 --> 00:17:38.799 align:start position:0% both intersect in one node even though both<00:17:35.929> of<00:17:36.139> the<00:17:36.230> quorums<00:17:36.590> have<00:17:37.039> selected<00:17:37.820> the 00:17:38.799 --> 00:17:38.809 align:start position:0% both of the quorums have selected the 00:17:38.809 --> 00:17:42.510 align:start position:0% both of the quorums have selected the two<00:17:39.020> faulty<00:17:39.409> nodes<00:17:40.360> and<00:17:41.360> anyway<00:17:41.690> this<00:17:41.960> area 00:17:42.510 --> 00:17:42.520 align:start position:0% two faulty nodes and anyway this area 00:17:42.520 --> 00:17:45.100 align:start position:0% two faulty nodes and anyway this area there's<00:17:43.520> a<00:17:43.580> general<00:17:43.909> result<00:17:44.210> which<00:17:44.480> is<00:17:44.690> the 00:17:45.100 --> 00:17:45.110 align:start position:0% there's a general result which is the 00:17:45.110 --> 00:17:48.430 align:start position:0% there's a general result which is the the<00:17:45.620> the<00:17:46.460> must<00:17:46.639> be<00:17:46.760> less<00:17:47.000> than<00:17:47.270> the<00:17:48.139> number<00:17:48.289> of 00:17:48.430 --> 00:17:48.440 align:start position:0% the the must be less than the number of 00:17:48.440 --> 00:17:51.220 align:start position:0% the the must be less than the number of faulty<00:17:49.190> nodes<00:17:49.399> must<00:17:49.700> be<00:17:50.570> less<00:17:50.750> than<00:17:50.779> a<00:17:50.960> third 00:17:51.220 --> 00:17:51.230 align:start position:0% faulty nodes must be less than a third 00:17:51.230 --> 00:17:53.289 align:start position:0% faulty nodes must be less than a third right<00:17:52.130> so<00:17:52.370> less<00:17:52.549> than<00:17:52.730> a<00:17:52.789> third<00:17:53.059> of<00:17:53.179> the 00:17:53.289 --> 00:17:53.299 align:start position:0% right so less than a third of the 00:17:53.299 --> 00:17:56.049 align:start position:0% right so less than a third of the processes<00:17:54.429> participating<00:17:55.429> in<00:17:55.490> the<00:17:55.580> consensus 00:17:56.049 --> 00:17:56.059 align:start position:0% processes participating in the consensus 00:17:56.059 --> 00:17:59.019 align:start position:0% processes participating in the consensus algorithm<00:17:56.320> must<00:17:57.320> be<00:17:57.620> faulty<00:17:58.220> for<00:17:58.700> the<00:17:58.820> thing 00:17:59.019 --> 00:17:59.029 align:start position:0% algorithm must be faulty for the thing 00:17:59.029 --> 00:18:05.490 align:start position:0% algorithm must be faulty for the thing to<00:17:59.270> be<00:17:59.389> able<00:17:59.450> to<00:17:59.630> reach<00:18:00.100> a<00:18:01.100> correct<00:18:01.940> result<00:18:02.240> and 00:18:05.490 --> 00:18:05.500 align:start position:0% 00:18:05.500 --> 00:18:08.920 align:start position:0% the<00:18:06.500> issue<00:18:07.190> there<00:18:07.640> is<00:18:07.850> that<00:18:08.150> one<00:18:08.390> of<00:18:08.420> the<00:18:08.600> one 00:18:08.920 --> 00:18:08.930 align:start position:0% the issue there is that one of the one 00:18:08.930 --> 00:18:10.420 align:start position:0% the issue there is that one of the one of<00:18:08.960> the<00:18:09.080> issues<00:18:09.170> one<00:18:09.740> of<00:18:09.800> them<00:18:09.920> other<00:18:10.160> things 00:18:10.420 --> 00:18:10.430 align:start position:0% of the issues one of them other things 00:18:10.430 --> 00:18:14.400 align:start position:0% of the issues one of them other things were<00:18:10.550> thinking<00:18:10.850> about<00:18:10.880> is<00:18:11.030> that<00:18:12.100> if<00:18:13.100> we<00:18:13.520> cannot 00:18:14.400 --> 00:18:14.410 align:start position:0% were thinking about is that if we cannot 00:18:14.410 --> 00:18:17.560 align:start position:0% were thinking about is that if we cannot wait<00:18:15.410> for<00:18:16.280> all<00:18:16.490> of<00:18:16.670> the<00:18:16.760> messages<00:18:16.940> so<00:18:17.360> let's 00:18:17.560 --> 00:18:17.570 align:start position:0% wait for all of the messages so let's 00:18:17.570 --> 00:18:20.620 align:start position:0% wait for all of the messages so let's say<00:18:17.780> you<00:18:17.810> know<00:18:18.080> they're<00:18:18.320> there<00:18:18.860> n<00:18:19.630> processes 00:18:20.620 --> 00:18:20.630 align:start position:0% say you know they're there n processes 00:18:20.630 --> 00:18:21.970 align:start position:0% say you know they're there n processes and<00:18:20.720> the<00:18:20.810> consensus<00:18:21.080> protocol<00:18:21.590> in<00:18:21.650> this<00:18:21.770> case 00:18:21.970 --> 00:18:21.980 align:start position:0% and the consensus protocol in this case 00:18:21.980 --> 00:18:25.240 align:start position:0% and the consensus protocol in this case there<00:18:22.190> are<00:18:22.250> seven<00:18:22.640> and<00:18:23.350> we<00:18:24.350> know<00:18:24.500> up<00:18:24.710> to<00:18:24.740> two<00:18:25.100> of 00:18:25.240 --> 00:18:25.250 align:start position:0% there are seven and we know up to two of 00:18:25.250 --> 00:18:28.420 align:start position:0% there are seven and we know up to two of them<00:18:25.430> can<00:18:25.760> be<00:18:25.940> faulty<00:18:26.420> right<00:18:27.220> once<00:18:28.220> we've 00:18:28.420 --> 00:18:28.430 align:start position:0% them can be faulty right once we've 00:18:28.430 --> 00:18:31.180 align:start position:0% them can be faulty right once we've received<00:18:28.580> five<00:18:29.180> messages<00:18:29.780> right<00:18:30.710> five 00:18:31.180 --> 00:18:31.190 align:start position:0% received five messages right five 00:18:31.190 --> 00:18:34.720 align:start position:0% received five messages right five messages<00:18:32.530> do<00:18:33.530> we<00:18:33.650> wait<00:18:33.890> and<00:18:34.220> see<00:18:34.400> if<00:18:34.460> we<00:18:34.580> can 00:18:34.720 --> 00:18:34.730 align:start position:0% messages do we wait and see if we can 00:18:34.730 --> 00:18:37.510 align:start position:0% messages do we wait and see if we can receive<00:18:35.150> another<00:18:35.480> two<00:18:35.840> right<00:18:36.560> there's<00:18:36.980> evil<00:18:37.280> 7 00:18:37.510 --> 00:18:37.520 align:start position:0% receive another two right there's evil 7 00:18:37.520 --> 00:18:42.580 align:start position:0% receive another two right there's evil 7 we<00:18:37.880> can't<00:18:38.150> write<00:18:38.420> because<00:18:38.920> the<00:18:40.510> remaining<00:18:41.590> two 00:18:42.580 --> 00:18:42.590 align:start position:0% we can't write because the remaining two 00:18:42.590 --> 00:18:44.200 align:start position:0% we can't write because the remaining two messages<00:18:43.040> we<00:18:43.130> haven't<00:18:43.400> received<00:18:43.670> may<00:18:44.180> be 00:18:44.200 --> 00:18:44.210 align:start position:0% messages we haven't received may be 00:18:44.210 --> 00:18:46.240 align:start position:0% messages we haven't received may be coming<00:18:44.720> from<00:18:44.900> faulty<00:18:45.320> nodes<00:18:45.650> and<00:18:45.860> the<00:18:45.920> faulty 00:18:46.240 --> 00:18:46.250 align:start position:0% coming from faulty nodes and the faulty 00:18:46.250 --> 00:18:48.130 align:start position:0% coming from faulty nodes and the faulty nodes<00:18:46.460> may<00:18:46.730> just<00:18:46.970> decide<00:18:47.090> not<00:18:47.300> to<00:18:47.780> send<00:18:48.020> these 00:18:48.130 --> 00:18:48.140 align:start position:0% nodes may just decide not to send these 00:18:48.140 --> 00:18:50.470 align:start position:0% nodes may just decide not to send these messages<00:18:48.170> to<00:18:48.680> make<00:18:48.860> to<00:18:49.760> make<00:18:49.880> us<00:18:50.090> wait<00:18:50.270> forever 00:18:50.470 --> 00:18:50.480 align:start position:0% messages to make to make us wait forever 00:18:50.480 --> 00:18:54.550 align:start position:0% messages to make to make us wait forever right<00:18:50.870> so<00:18:52.240> these<00:18:53.240> kind<00:18:53.540> of<00:18:53.600> protocols<00:18:54.050> need<00:18:54.410> to 00:18:54.550 --> 00:18:54.560 align:start position:0% right so these kind of protocols need to 00:18:54.560 --> 00:18:57.880 align:start position:0% right so these kind of protocols need to proceed<00:18:54.740> when<00:18:55.400> they've<00:18:55.700> received<00:18:56.600> two<00:18:57.410> F<00:18:57.560> plus 00:18:57.880 --> 00:18:57.890 align:start position:0% proceed when they've received two F plus 00:18:57.890 --> 00:19:03.250 align:start position:0% proceed when they've received two F plus one<00:18:58.160> of<00:18:58.460> the<00:18:58.790> messages<00:19:00.670> which<00:19:01.670> has<00:19:02.260> another 00:19:03.250 --> 00:19:03.260 align:start position:0% one of the messages which has another 00:19:03.260 --> 00:19:06.400 align:start position:0% one of the messages which has another side<00:19:03.530> effect<00:19:03.590> which<00:19:04.130> is<00:19:04.310> that<00:19:04.610> of<00:19:05.080> course<00:19:06.080> it 00:19:06.400 --> 00:19:06.410 align:start position:0% side effect which is that of course it 00:19:06.410 --> 00:19:09.040 align:start position:0% side effect which is that of course it may<00:19:06.620> be<00:19:06.680> that<00:19:06.830> the<00:19:07.400> F<00:19:07.640> messages<00:19:08.330> that<00:19:08.960> we 00:19:09.040 --> 00:19:09.050 align:start position:0% may be that the F messages that we 00:19:09.050 --> 00:19:11.920 align:start position:0% may be that the F messages that we didn't<00:19:09.350> wait<00:19:09.470> for<00:19:09.500> in<00:19:09.770> this<00:19:09.830> case<00:19:10.070> to<00:19:10.930> two 00:19:11.920 --> 00:19:11.930 align:start position:0% didn't wait for in this case to two 00:19:11.930 --> 00:19:13.420 align:start position:0% didn't wait for in this case to two messages<00:19:12.290> we<00:19:12.410> didn't<00:19:12.650> wait<00:19:12.770> for<00:19:12.800> we're 00:19:13.420 --> 00:19:13.430 align:start position:0% messages we didn't wait for we're 00:19:13.430 --> 00:19:15.040 align:start position:0% messages we didn't wait for we're actually<00:19:13.640> from<00:19:13.940> correct<00:19:14.300> processes<00:19:14.750> and 00:19:15.040 --> 00:19:15.050 align:start position:0% actually from correct processes and 00:19:15.050 --> 00:19:18.490 align:start position:0% actually from correct processes and we've<00:19:15.170> received<00:19:16.000> two<00:19:17.000> messages<00:19:17.030> from<00:19:17.900> faulty 00:19:18.490 --> 00:19:18.500 align:start position:0% we've received two messages from faulty 00:19:18.500 --> 00:19:20.560 align:start position:0% we've received two messages from faulty processes<00:19:19.130> in<00:19:19.310> which<00:19:19.370> which<00:19:19.940> means<00:19:20.240> that<00:19:20.330> we 00:19:20.560 --> 00:19:20.570 align:start position:0% processes in which which means that we 00:19:20.570 --> 00:19:24.940 align:start position:0% processes in which which means that we can<00:19:20.690> only<00:19:20.780> be<00:19:20.930> sure<00:19:21.760> f<00:19:22.760> plus<00:19:23.210> 1<00:19:23.600> messages<00:19:24.230> from 00:19:24.940 --> 00:19:24.950 align:start position:0% can only be sure f plus 1 messages from 00:19:24.950 --> 00:19:26.950 align:start position:0% can only be sure f plus 1 messages from those<00:19:25.160> who<00:19:25.280> have<00:19:25.370> collected<00:19:25.850> from<00:19:26.180> correct 00:19:26.950 --> 00:19:26.960 align:start position:0% those who have collected from correct 00:19:26.960 --> 00:19:29.320 align:start position:0% those who have collected from correct processes<00:19:27.380> and<00:19:27.650> that's<00:19:28.340> why<00:19:28.520> it's<00:19:28.670> kind<00:19:29.300> of 00:19:29.320 --> 00:19:29.330 align:start position:0% processes and that's why it's kind of 00:19:29.330 --> 00:19:35.560 align:start position:0% processes and that's why it's kind of complex<00:19:29.770> so<00:19:32.920> I'm<00:19:33.920> at<00:19:34.100> a<00:19:34.190> time<00:19:34.400> so<00:19:34.940> you're<00:19:35.210> saved 00:19:35.560 --> 00:19:35.570 align:start position:0% complex so I'm at a time so you're saved 00:19:35.570 --> 00:19:37.800 align:start position:0% complex so I'm at a time so you're saved I<00:19:35.750> was<00:19:35.870> going<00:19:35.990> to<00:19:36.050> try<00:19:36.230> and<00:19:36.320> walk<00:19:36.680> you<00:19:36.800> through 00:19:37.800 --> 00:19:37.810 align:start position:0% I was going to try and walk you through 00:19:37.810 --> 00:19:42.450 align:start position:0% I was going to try and walk you through in<00:19:38.810> a<00:19:38.930> synchronous<00:19:39.370> protocol<00:19:40.370> but 00:19:42.450 --> 00:19:42.460 align:start position:0% in a synchronous protocol but 00:19:42.460 --> 00:19:45.340 align:start position:0% in a synchronous protocol but i'm<00:19:43.460> at<00:19:43.639> a<00:19:43.669> time<00:19:43.850> but<00:19:44.000> if<00:19:44.090> anyone's<00:19:44.389> the<00:19:44.779> deck 00:19:45.340 --> 00:19:45.350 align:start position:0% i'm at a time but if anyone's the deck 00:19:45.350 --> 00:19:50.830 align:start position:0% i'm at a time but if anyone's the deck ping<00:19:45.889> me<00:19:46.009> and<00:19:46.190> have<00:19:46.669> it<00:19:47.440> thank<00:19:48.440> you<00:19:48.590> so<00:19:48.769> much