WEBVTT - Automatic transcript; recognition may contain errors. Reviewed for technical wording and speaker labels. Times match the published episode. 00:00:19.410 --> 00:00:21.630 Live from Utrecht, this is Bitcoin. 00:00:22.130 --> 00:00:22.610 Explained. 00:00:23.090 --> 00:00:23.530 Hey, Sjors. 00:00:23.950 --> 00:00:24.370 Hello. 00:00:25.230 --> 00:00:31.030 So, here we are. After weeks of you complaining to me, DMing me, asking 00:00:31.030 --> 00:00:36.870 me every week, week after week, Aaron, Aaron, Aaron. I want Nigel Farage to 00:00:36.870 --> 00:00:41.170 come to Amsterdam. Nigel Farage needs to be a speaker at Bitcoin Amsterdam. 00:00:41.430 --> 00:00:43.570 Finally, Sjors, I can tell you, he's coming. 00:00:44.420 --> 00:00:48.620 Okay. I think I heard the rumor earlier today and I was like... 00:00:48.600 --> 00:00:53.660 Okay he'll be there so it's a happy day for you Sjors, I know he's your favorite 00:00:53.660 --> 00:00:54.280 politician. 00:00:54.280 --> 00:00:55.320 He is? 00:00:55.320 --> 00:01:01.010 Okay and you dear listeners if you want to see Nigel the great Nigel Farage 00:01:01.010 --> 00:01:06.230 I'm in case anyone doesn't know this I'm being a bit sarcastic but in case you 00:01:06.230 --> 00:01:07.390 want to come to Bitcoin Amsterdam 00:01:07.390 --> 00:01:09.790 Does he even have a passport to travel outside the UK? 00:01:09.790 --> 00:01:15.430 Yeah I I don't know why he would want to right But let me finish my thought. If 00:01:15.430 --> 00:01:19.690 you want to come and if you want to meet Nigel Farage or at least hear him speak, 00:01:19.930 --> 00:01:25.930 use the promo code Sjorsnado. Let's see if anyone out there can remember 00:01:25.930 --> 00:01:29.310 Sjorsnado and use it as a promo code. You'll get 10% off. 00:01:30.970 --> 00:01:31.370 Okay. 00:01:31.630 --> 00:01:36.310 That's my sort of, I'm now just shilling the conference before we start the 00:01:36.310 --> 00:01:38.490 episode. I hope you don't mind too much. 00:01:38.730 --> 00:01:39.810 That's what we did last time. 00:01:40.010 --> 00:01:44.630 Yeah, I think this is the third time. All right, let's move on. Sjors, today 00:01:44.630 --> 00:01:45.530 you've got a new hobby. 00:01:45.870 --> 00:01:46.490 I have a new hobby. 00:01:46.570 --> 00:01:47.410 What am I looking at here? 00:01:47.610 --> 00:01:48.730 You're looking at an anvil. 00:01:49.090 --> 00:01:53.290 You've got an actual miniature anvil on your desk right here. 00:01:53.670 --> 00:01:54.330 That's right. 00:01:54.690 --> 00:01:57.850 And you're using that for what exactly? 00:01:58.390 --> 00:02:02.090 Well, right now I'm just using it as a nice decorative element. But I want to 00:02:02.090 --> 00:02:06.150 hobby around a bit with these QR codes that you can basically put in steel plates. 00:02:06.720 --> 00:02:09.780 Right. You're going to hammer your private keys into steel. 00:02:09.980 --> 00:02:13.300 Or some testnet private key probably, but we'll see. 00:02:13.380 --> 00:02:18.420 Fair enough. Yes. Well, so the specific thing we're going to discuss is SeedQR. 00:02:18.720 --> 00:02:20.100 This is something you proposed. 00:02:20.440 --> 00:02:20.560 Yes. 00:02:20.560 --> 00:02:23.620 I'd never heard of it. I don't know where you found it. And I think you didn't 00:02:23.620 --> 00:02:24.860 remember where you found it either. 00:02:24.980 --> 00:02:25.420 I remember. 00:02:25.780 --> 00:02:26.620 Oh, where did you find it? 00:02:26.620 --> 00:02:29.920 Yeah, I was on Twitter as I sometimes do. 00:02:30.140 --> 00:02:30.700 As usual. 00:02:30.880 --> 00:02:36.300 And I was doom scrolling. And then I saw this really cool video of somebody 00:02:36.300 --> 00:02:41.200 writing down with pen and paper a QR code, just with regular pen and paper, 00:02:41.400 --> 00:02:46.500 and scanning it, and it actually worked. So I was quite surprised to see that you 00:02:46.500 --> 00:02:48.620 can actually draw it by hand, and quite sloppily even. 00:02:49.020 --> 00:02:51.920 Why is that surprising? That doesn't surprise me at all. 00:02:52.040 --> 00:02:57.020 I was expecting it to be very sensitive. So if you don't print it with a computer 00:02:57.020 --> 00:03:00.820 and the squares are not perfectly square, then I thought it wouldn't work. But it 00:03:00.820 --> 00:03:03.820 turns out now you can do pretty sloppy work, and it still works. 00:03:04.100 --> 00:03:09.800 Right so basically you you can draw out a grid and start you know coloring some of the… 00:03:10.260 --> 00:03:14.500 Yeah, but I think he didn't even draw out a grid here. So yeah, it was just roughly. 00:03:14.500 --> 00:03:15.320 Oh, and it still works? 00:03:15.460 --> 00:03:15.580 Yep. 00:03:16.460 --> 00:03:21.520 That's actually pretty interesting then. So this was someone using SeedQR? Does 00:03:21.520 --> 00:03:22.080 this tie in? 00:03:22.200 --> 00:03:25.600 Yeah, so I was wondering like, what is that? You know, what's behind that? What's 00:03:25.600 --> 00:03:29.540 the standard or maybe a proposed standard? And yeah, so there's apparently 00:03:29.540 --> 00:03:34.760 something out there called SeedQR. And the context in which it's used is a 00:03:34.760 --> 00:03:37.840 device. I guess we'll get to that later. It's called the device called the 00:03:37.840 --> 00:03:43.560 SeedSigner. And that is not really a company. It's just an open standard for how 00:03:43.560 --> 00:03:47.600 you can make your own device. So you buy, I think it's a Raspberry Mini or 00:03:47.600 --> 00:03:52.340 Arduino, something like that. Very tiny computer, has a little camera on it, and 00:03:52.340 --> 00:03:56.440 you install some software on it that's open source. And then you can use that to 00:03:56.440 --> 00:04:02.320 scan a QR code. And this QR code will then convert into your 12 words or 00:04:02.320 --> 00:04:02.940 24 words. 00:04:03.850 --> 00:04:04.210 Okay. 00:04:04.350 --> 00:04:07.870 And vice versa, you can use a keyboard, or it's not really a keyboard, just a 00:04:07.870 --> 00:04:12.830 couple of buttons to enter your 24 or 12 words, and it'll show you a QR code, and 00:04:12.830 --> 00:04:15.870 you can then draw that QR code on a piece of paper. That's kind of what it does. 00:04:16.130 --> 00:04:16.330 Right. 00:04:16.330 --> 00:04:19.130 We're getting a little ahead of ourselves, but that's what I was looking at. 00:04:19.310 --> 00:04:24.290 Yeah, let's just take this one step at a time, and then we'll get to whatever 00:04:24.290 --> 00:04:25.530 you're talking about in a minute. 00:04:26.780 --> 00:04:27.260 Okay. 00:04:27.660 --> 00:04:28.340 Sounds good. 00:04:28.540 --> 00:04:29.000 Sounds good. 00:04:29.300 --> 00:04:34.700 All right. There we go. So first of all, Sjors, how do people make sure they 00:04:34.700 --> 00:04:35.620 don't lose their Bitcoin? 00:04:35.920 --> 00:04:36.840 They make backups. 00:04:37.180 --> 00:04:37.560 Great. 00:04:37.780 --> 00:04:38.800 Or they become a no-coiner. 00:04:39.020 --> 00:04:44.550 Well, so people used to make backups. You know, back in the days, we all made 00:04:44.550 --> 00:04:50.110 backups, which basically meant you literally backed up every private key you had, right? 00:04:50.530 --> 00:04:54.070 Yeah, so I'm using the word backup very broadly. But back in the day, you 00:04:54.070 --> 00:04:57.890 actually had to make a backup in the more narrow sense that you click the button 00:04:57.890 --> 00:05:01.670 that says make backup and you store the backup somewhere else. So if you were 00:05:01.670 --> 00:05:06.030 using the old Bitcoin client before it was called Bitcoin Core, it came with a wallet. 00:05:07.750 --> 00:05:11.170 Yes, in order to not lose your coins, you had to make a backup of the wallet. But 00:05:11.170 --> 00:05:17.110 not just once. Initially, every time you made a new receive address, it would 00:05:17.110 --> 00:05:20.910 be a completely random receive address. So you'd have to make a backup every time 00:05:20.910 --> 00:05:24.730 you received coins. Or at some point, I think it was improved, so it would make 00:05:24.730 --> 00:05:28.870 100 receive addresses in the background. And you'd make a backup of those 100 00:05:28.870 --> 00:05:33.890 addresses. If you forgot to do that, you would suddenly lose all your coins if 00:05:33.890 --> 00:05:35.610 you restored an old backup. 00:05:36.640 --> 00:05:42.040 Right okay so the problem with this for one is you need a lot of well maybe not a 00:05:42.040 --> 00:05:47.200 lot but you need to back up a bunch of data one for each transaction one for each 00:05:47.200 --> 00:05:50.680 receiving transaction because ideally of course you make a new address for each 00:05:50.680 --> 00:05:54.540 transaction as we've explained like three episodes ago I think. 00:05:54.980 --> 00:05:56.220 We've mentioned it a couple of times. 00:05:56.700 --> 00:05:58.200 It's also somewhat everyone knows. 00:05:58.400 --> 00:06:01.280 And so you didn't have to do it every transaction. I think you would have to do 00:06:01.280 --> 00:06:04.860 it every 100 transactions or something, and they would just make 100 backups, 00:06:04.960 --> 00:06:08.520 something like that. But anyway, if you forgot to do that, your coins, not only 00:06:08.520 --> 00:06:12.160 do you use new receive addresses, even if you use the same receive address every 00:06:12.160 --> 00:06:16.320 time, when you're sending coins, you create a change address, your wallet. And 00:06:16.320 --> 00:06:20.650 your wallet will create new change addresses because it's very disciplined. And 00:06:20.650 --> 00:06:24.950 so when you hit change address number 101 or whatever it was, and you don't have 00:06:24.950 --> 00:06:29.690 a backup of number 101, now all your coins went to this new change address and 00:06:29.690 --> 00:06:30.210 they're all gone. 00:06:30.670 --> 00:06:36.230 If your computer crashes or something yeah yeah okay so this was improved we're 00:06:36.230 --> 00:06:39.030 just gonna have to kind of rush through this because we've discussed it before 00:06:39.030 --> 00:06:42.810 and I think we've even had entire episodes about some of this stuff like for 00:06:42.810 --> 00:06:47.450 example the thing we're gonna mention now are seeds I think we've had a whole 00:06:47.450 --> 00:06:51.190 episode it was like episode it was an early episode what is an xpub? 00:06:51.190 --> 00:06:52.850 Yeah that's a famous episode. 00:06:53.500 --> 00:06:55.100 Is it a famous episode? 00:06:55.320 --> 00:06:55.880 No, I don't know. 00:06:56.660 --> 00:07:00.240 I think all of our... Well, actually, none of our episodes are famous, I'd say. 00:07:02.140 --> 00:07:04.480 BIP 32, that's seeds. So what is seed? 00:07:05.710 --> 00:07:08.210 Am I saying that right? No, no, no, I'm saying it wrong. 00:07:08.230 --> 00:07:13.840 Seed, yes, but it's not a mnemonic. So basically, a seed just means one key that 00:07:13.840 --> 00:07:16.480 creates all the other keys. So it's like a plant seed. 00:07:16.720 --> 00:07:17.120 Right, yep. 00:07:17.260 --> 00:07:21.280 And so what BIP 32 did is you create this one master seed, master key, or 00:07:21.280 --> 00:07:22.120 whatever you want to call it. 00:07:23.490 --> 00:07:26.770 And that's the thing you backup, which is the first thing you do when you get the 00:07:26.770 --> 00:07:31.700 new wallet. You backup this master seed and you're good. Then what happens is you 00:07:31.700 --> 00:07:37.580 have a tree of derivations, basically, so that each address is unique, but 00:07:37.580 --> 00:07:41.660 it is all derivable from this one seed. So that's how you can restore it. 00:07:41.920 --> 00:07:45.580 Just to jog my own memory, really. I mean, if I don't remember, probably some of 00:07:45.580 --> 00:07:50.240 our listeners don't. Is it essentially just the case that you... generate a first 00:07:50.240 --> 00:07:53.640 private key and then you hash the private key and the hash and the hash and the 00:07:53.640 --> 00:07:57.020 hash and that's just new private keys or is it a bit more complicated? 00:07:57.020 --> 00:08:00.840 It is a bit more complicated but it really boils down to that you right hash it 00:08:00.840 --> 00:08:04.480 and maybe you add the number one and there's some some nuance there but yeah. 00:08:04.480 --> 00:08:06.960 That's essentially the gist of it all right. 00:08:06.960 --> 00:08:09.900 It's deterministic so your wallet will know what to do. 00:08:09.900 --> 00:08:10.360 Right. 00:08:10.360 --> 00:08:13.280 Once it gets a seed. It will know how to find the addresses that you've used before. 00:08:13.280 --> 00:08:18.420 Sure okay now then I guess the problem here again we're rushing through it a bit 00:08:18.420 --> 00:08:22.640 through this part. The problem here is that remembering even the seed, even the 00:08:22.640 --> 00:08:27.240 first private key is a little bit hard. Not for you, of course, but for regular 00:08:27.240 --> 00:08:31.260 people like me and most of our listeners, we don't actually remember that kind of 00:08:31.260 --> 00:08:33.000 stuff. So we need something that's a bit easier. 00:08:33.320 --> 00:08:36.700 Well, so the thing is, initially with the Bitcoin client, you would just back up 00:08:36.700 --> 00:08:42.020 on a USB stick or something like that, right? It'd still be a digital backup. And 00:08:42.020 --> 00:08:45.360 so some people would prefer to have a backup that's physical, that's probably 00:08:45.360 --> 00:08:49.320 written on a piece of paper. And that means, yeah, then it gets really cumbersome 00:08:49.320 --> 00:08:55.060 to start writing these hexadecimal things down, if you can even find them. Right. 00:08:55.060 --> 00:08:58.500 It's not even about memory. You shouldn't even use your memory. You should write 00:08:58.500 --> 00:09:00.920 it down either way. But we need an easier way to write it down. 00:09:01.160 --> 00:09:01.300 Yeah. 00:09:02.820 --> 00:09:07.560 And I guess that's another thing. So then there was this idea called BIP 39, 00:09:07.580 --> 00:09:12.600 which is a mnemonic. And the idea is really you just take the letters or the 00:09:12.600 --> 00:09:18.220 hexadecimal numbers and you just map them onto words. So there's 4,000 words 00:09:18.220 --> 00:09:19.460 and each... 00:09:19.460 --> 00:09:21.860 No, there's 2,048 words, I think. 00:09:22.000 --> 00:09:25.120 Okay. Some... Those just map onto the numbers. 00:09:25.360 --> 00:09:29.900 It's 2 to the 12th. 2 to the power of 12th. That's 2048. 00:09:30.320 --> 00:09:33.660 That sounds like 4,000. 2 to the power of 10 is 1,000. 00:09:34.650 --> 00:09:40.270 No, I'm pretty sure. I looked it up this afternoon. So I think it's 2048 words. 00:09:40.510 --> 00:09:43.210 But there may be several standards, right? Aren't there several? 00:09:43.410 --> 00:09:44.470 Well, I'm talking about BIP 39. 00:09:45.030 --> 00:09:45.630 Me too. 00:09:45.830 --> 00:09:49.950 So there's a number of words, which we'll have to look up. And they really, those 00:09:49.950 --> 00:09:53.570 words just represent numbers, essentially. So that's that simple. 00:09:54.170 --> 00:10:00.150 Basically, it's just the first word is number 0000. They all 00:10:00.150 --> 00:10:05.930 have four numbers, right? And then the second word is 0001, and that's all the way through. 00:10:06.250 --> 00:10:12.110 Exactly. Now, there is a little caveat there. It works one way, as in you 00:10:12.110 --> 00:10:16.130 start with the numbers. So the numbers are the seed you generated, essentially, 00:10:16.610 --> 00:10:22.360 your computer generated, and then they are converted to words. But when you use 00:10:22.360 --> 00:10:26.040 it, it's actually not using the words. Sorry, it's not going back to the numbers. 00:10:26.160 --> 00:10:30.380 So when you enter the words, the next step in order to create this hierarchical 00:10:30.380 --> 00:10:36.040 wallet is to just process the words as they are written and hash that. 00:10:37.650 --> 00:10:40.810 It's a little implementation detail that you generally don't have to worry about 00:10:40.810 --> 00:10:43.240 unless you want to do translations. 00:10:44.470 --> 00:10:50.370 So basically the first address of your wallet is derived. So you start with this 00:10:50.370 --> 00:10:56.300 random numbers. Those are turned into words, and those words pasted behind 00:10:56.300 --> 00:11:00.540 each other, and maybe with a little password behind it, those are hashed, and 00:11:00.540 --> 00:11:01.980 that's where the first key comes from. 00:11:04.600 --> 00:11:09.800 But that means that if you have, say, a German alternative for this BIP 39, 00:11:10.400 --> 00:11:15.530 that... If you start with the same numbers, but now you start to write German 00:11:15.530 --> 00:11:19.190 words, and when you hash the German words, you're going to get a different key 00:11:19.190 --> 00:11:23.390 than when you hash English words. So you cannot translate one seed into another. 00:11:23.550 --> 00:11:24.770 That makes no sense. 00:11:25.290 --> 00:11:26.470 Right. Okay. 00:11:27.630 --> 00:11:32.650 And this is relevant because that's one reason why I don't think it's a good idea 00:11:32.650 --> 00:11:35.630 for people to use BIP-39 in other languages. 00:11:36.830 --> 00:11:40.670 Because in that case, you may have one piece of software that will understand 00:11:40.670 --> 00:11:44.410 what to do with the German words, but your other piece of software that you may 00:11:44.410 --> 00:11:48.670 want to use later, your other wallet, will not understand it. Because most of the 00:11:48.670 --> 00:11:49.690 support is for the English words. 00:11:50.850 --> 00:11:56.410 Right. Okay, well, I didn't know that. Is it important for the rest of the episode? 00:11:56.590 --> 00:12:00.810 It's not important for the rest of the episode. It is one of those things that if 00:12:00.810 --> 00:12:04.030 we ever had to redo these standards, that we should do better. 00:12:04.370 --> 00:12:09.510 Right. I do have another question. So some seeds have 12 words and some have 00:12:09.510 --> 00:12:15.170 24. I think these are the two most common amounts of words. 00:12:15.530 --> 00:12:18.130 Why is there a difference? Is one just more secure? 00:12:18.670 --> 00:12:23.980 Yeah, it's more bits. So 12 words means 128 bits. Of random data. 00:12:24.480 --> 00:12:28.820 So basically throwing coins. Yeah, you're basically throwing 128 coins. 00:12:30.190 --> 00:12:31.470 For heads of tails, yeah. 00:12:31.690 --> 00:12:37.150 Yes. Or if you have 24 words, you're effectively throwing 256 coins, heads of 00:12:37.150 --> 00:12:40.810 tails. And that is not twice as secure. That is like... 00:12:40.810 --> 00:12:42.010 A lot more secure. 00:12:42.230 --> 00:12:42.370 Yeah. 00:12:42.790 --> 00:12:43.670 What's the numbers, Sjors? 00:12:43.910 --> 00:12:44.750 Well, I don't know. 00:12:44.970 --> 00:12:45.770 From the top of your head, come on. 00:12:45.850 --> 00:12:48.270 It's basically twice as many bits of security. 00:12:48.670 --> 00:12:49.110 Yeah. 00:12:49.530 --> 00:12:55.140 But... It takes a lot more time to brute force it. Because every bit you add 00:12:55.140 --> 00:12:58.520 means it takes twice as long to brute force it. If you want to guess what 00:12:58.520 --> 00:13:03.700 somebody's mnemonic is, you try one combination of words, you try another, you 00:13:03.700 --> 00:13:09.000 try another, you try another. And if it's a two-bit system, if it's a two-bit 00:13:09.000 --> 00:13:14.740 seed, well, then you just have to try four times. But if it is a 4-bit seed, 00:13:14.940 --> 00:13:17.440 you don't have to try 8 times, you have to try 16 times. 00:13:17.660 --> 00:13:22.260 So is 12 enough then? Why don't all wallets just use... If some wallets use 24, 00:13:22.440 --> 00:13:23.900 why don't they all use 24? 00:13:24.680 --> 00:13:30.160 I mean, ultimately, it's better to have more bits of security. If there's no 00:13:30.160 --> 00:13:35.860 trade-off, why not? Right and ultimately in the long run you know the worry is 00:13:35.860 --> 00:13:40.160 that as computers get faster or as problems are found you need more bits to be 00:13:40.160 --> 00:13:44.660 really secure and maybe one day we'll reach the point where 128 bit is not secure 00:13:44.660 --> 00:13:49.040 anymore but then 256 will last us a bit longer so it's it's that kind of 00:13:49.040 --> 00:13:50.040 long-term thinking. 00:13:50.040 --> 00:13:54.120 Is it maybe also partly a human problem like some people will cut their seed in 00:13:54.120 --> 00:13:58.020 half thinking if they hide them in different places then they're good but then if 00:13:58.380 --> 00:13:59.960 [unclear] if someone… 00:13:59.960 --> 00:14:03.960 Yeah so then you're getting really in trouble right because six if you have a 12 00:14:03.960 --> 00:14:09.780 word seed and you cut it in two that's six words each and that is only 64 bits of 00:14:09.780 --> 00:14:14.340 entropy that's still that's still a lot but it might be within the realm of 00:14:14.340 --> 00:14:18.560 something you can crack because again Twice as long does not mean that it takes 00:14:18.560 --> 00:14:22.620 twice as long to crack it. It means it takes exponentially longer to crack it. 00:14:23.020 --> 00:14:23.160 Yep. 00:14:23.640 --> 00:14:26.480 So that's indeed one of the risks, but I don't think that's the reason. So 00:14:26.480 --> 00:14:31.640 basically, you could say that the limit of Bitcoin, the way it's architected, is 00:14:31.640 --> 00:14:37.480 256 bits. And that is because the hashes of a block, as well as the elliptic 00:14:37.480 --> 00:14:40.480 curve, all use 64 bits, 256 bits. 00:14:41.800 --> 00:14:47.800 So if you have a way to crack a 256-bit number, like find the private key, 00:14:47.880 --> 00:14:50.920 etc., that's basically the security level anyway. So you might as well use that. 00:14:51.100 --> 00:14:52.100 Broken Bitcoin itself, yeah. 00:14:52.480 --> 00:14:56.520 Yeah. So that's why I guess that's one argument to say, well, then why don't you 00:14:56.520 --> 00:15:00.880 use seeds that are at that limit? It makes no sense to go beyond it, but it also 00:15:00.880 --> 00:15:05.260 makes no sense to stay below it. All things equal. Because you do have to write 00:15:05.260 --> 00:15:09.520 these things down or do something else with it. And if that's too much work, then 00:15:09.520 --> 00:15:15.520 people won't do it. And then you just lose your coins. So the benefit of 00:15:15.520 --> 00:15:17.780 12 words is that people are more likely to write them down. 00:15:18.930 --> 00:15:23.670 Okay, now let's get to the meat of this episode. I think that was a long recap of 00:15:23.670 --> 00:15:28.150 stuff that people already knew, or at least most people already knew most of 00:15:28.150 --> 00:15:34.150 that. So now we're getting to SeedQR, and this is your hobby project. So I guess 00:15:34.150 --> 00:15:35.330 Sjors, just explain what it is. 00:15:36.010 --> 00:15:40.110 Yeah, so as far as I know, it's a proposed standard, and there are some tools 00:15:40.110 --> 00:15:45.370 that are using it. And the idea is that you take these 12 to 24 words, and rather 00:15:45.370 --> 00:15:49.950 than writing them down as words, you convert them into a QR code. Because 00:15:49.950 --> 00:15:53.230 remember, these things represent numbers. So you just take the word, find the 00:15:53.230 --> 00:15:57.170 corresponding number, and now you have a bunch of numbers. And if you have a 00:15:57.170 --> 00:16:02.110 bunch of numbers, essentially, if you have 128 bits of data or 256 bits of data, 00:16:02.330 --> 00:16:05.150 you can squeeze that into a very small QR code. 00:16:05.900 --> 00:16:11.800 Right. So right now a lot of people are storing their Bitcoin essentially, 00:16:12.000 --> 00:16:16.840 their private keys as a list of, or at least their backup as a list of words. And 00:16:16.840 --> 00:16:22.740 according to, with this standard, they could backup their keys as a 00:16:22.740 --> 00:16:24.020 QR code, which they... 00:16:24.610 --> 00:16:27.790 Yeah. And so one benefit of that could be... 00:16:27.790 --> 00:16:32.950 Is that new? I mean, I've never heard of it, but it sounds like a fairly obvious 00:16:32.950 --> 00:16:34.290 thing to do, but it's new. 00:16:34.450 --> 00:16:38.290 Yeah. I mean, it really depends on your use case, right? So if you have your keys 00:16:38.290 --> 00:16:43.820 in some very far away cold storage place in the middle of the Antarctica, well, 00:16:44.950 --> 00:16:49.650 it may be useful for you. If you need those words anyway, you can either type 00:16:49.650 --> 00:16:53.670 them or you can scan them, right? Those are the two ways you can enter them back 00:16:53.670 --> 00:16:58.650 into a machine. And since most hardware wallets are a pain in the ass to type on, 00:16:59.450 --> 00:17:04.810 maybe using a camera might be easier. But I think only the Jade hardware wallet 00:17:04.810 --> 00:17:10.710 and the Specter DIY wallet have cameras. So there's only 00:17:10.710 --> 00:17:12.010 limited use for QR codes. 00:17:12.470 --> 00:17:17.770 Okay, so the general idea is we're using a QR code as a backup. What 00:17:17.770 --> 00:17:19.450 are the challenges here? 00:17:19.570 --> 00:17:23.090 Yeah, and not just as a backup. It could even be, let's say you have a phone wallet. 00:17:24.890 --> 00:17:28.290 And when you're walking around with your phone, maybe it's a phone wallet that 00:17:28.290 --> 00:17:31.850 you don't use for shopping, but you do use it for your, I don't know, everyday 00:17:31.850 --> 00:17:35.410 stuff. It's not like cold storage. It's not a huge amount of money. But when 00:17:35.410 --> 00:17:39.030 somebody robs you in the street, you don't want to be able to give them Bitcoin. 00:17:39.030 --> 00:17:42.550 So you don't want to have the private keys on the phone itself. You want to have 00:17:42.550 --> 00:17:46.250 them somewhere safe at home. And so then a QR code could be useful because when 00:17:46.250 --> 00:17:50.430 you do want to use it, you just scan the QR code. And now, boom, you can spend 00:17:50.430 --> 00:17:54.250 your Bitcoin. But when you're on the street, nobody can rob you. If they go to 00:17:54.250 --> 00:17:56.170 your home, they can. You know, that's a trade-off. 00:17:56.410 --> 00:18:00.270 Right. So the idea there would be that your phone doesn't actually store any of 00:18:00.270 --> 00:18:05.030 the keys. It just scans them for one-time use. It scans the QR code for one-time 00:18:05.030 --> 00:18:08.350 use and then forgets it. And it can be a phone. It can also be another device, of 00:18:08.350 --> 00:18:11.570 course. It could be a hardware wallet that operates like this. So then the keys 00:18:11.570 --> 00:18:12.830 aren't even on the device. 00:18:13.030 --> 00:18:16.270 Yeah, well, they are when you're using it. But after that, they're not. Well, 00:18:16.390 --> 00:18:17.090 unless it was compromised. 00:18:17.620 --> 00:18:23.060 Right, so rather than thinking of it as a backup, in that case, it is essentially 00:18:23.060 --> 00:18:25.240 your actual cold storage wallet. 00:18:26.240 --> 00:18:30.460 Yeah, or at least your actual offline, semi-offline wallet or something like that. 00:18:30.700 --> 00:18:36.500 Right, right, right. Okay, so what are the challenges to accomplishing this, 00:18:36.520 --> 00:18:38.180 if there are any? 00:18:38.950 --> 00:18:42.850 Well, for one thing is, again, it depends on the use case. For the easy use case 00:18:42.850 --> 00:18:46.970 where you are printing a QR code with a physical printer, then I guess it doesn't 00:18:46.970 --> 00:18:49.690 matter, right? You can make a very big QR code or a very small one. It doesn't 00:18:49.690 --> 00:18:53.930 matter. But when you, as we described in the beginning, you want to write down 00:18:53.930 --> 00:18:58.630 your QR code on a piece of paper, which you can draw. It's nice if the QR code is 00:18:58.630 --> 00:19:02.130 not too many little points because it's very tedious to do it. And if you want to 00:19:02.130 --> 00:19:04.120 put them on metal, 00:19:05.390 --> 00:19:10.170 then you really don't want to have 5,000 little points that you need to put on 00:19:10.170 --> 00:19:10.750 the QR code. 00:19:10.930 --> 00:19:16.630 Right. And I guess the reason this matters is that you ideally 00:19:16.630 --> 00:19:22.330 don't want to have your private keys touch. A computer at all, possibly, 00:19:22.550 --> 00:19:24.050 or a printer at all. 00:19:24.230 --> 00:19:24.450 Exactly. 00:19:24.870 --> 00:19:28.810 These things can be hacked, and I think some printers even have memory of stuff 00:19:28.810 --> 00:19:33.150 they printed. Ideally, it just flashed on your hardware wallet or something, and 00:19:33.150 --> 00:19:34.370 then you write it down with a pen and paper. 00:19:34.370 --> 00:19:38.470 Exactly, and that's what the SeedSigner does. So the SeedSigner is a sort of 00:19:38.470 --> 00:19:41.650 open-source device where you can buy off-the-shelf components and make it 00:19:41.650 --> 00:19:46.390 yourself. What this device does is you enter your words, and it shows you the QR 00:19:46.390 --> 00:19:51.180 code, or you scan the QR code, and it shows you the words. And then I think that 00:19:51.180 --> 00:19:55.080 device can also sign things, but maybe you don't want to use that part. Maybe you 00:19:55.080 --> 00:19:58.560 want to use your regular hardware wallet for the signing. So you then take your 00:19:58.560 --> 00:20:01.500 mnemonic and put it in your regular hardware wallet, something like that. That 00:20:01.500 --> 00:20:04.540 could be the operation flow. And that means you're not using your main computer, 00:20:04.580 --> 00:20:07.680 which will probably have millions of viruses on it. You're not using your 00:20:07.680 --> 00:20:11.740 printer, which will probably have millions of viruses on it. And then it's really 00:20:11.740 --> 00:20:15.600 important because you're doing this step by hand, you're drawing a QR code. The 00:20:15.600 --> 00:20:17.340 drawing part should be as little work as possible. 00:20:17.540 --> 00:20:17.980 Right. 00:20:18.200 --> 00:20:21.320 So then they've done some research about how small these QR codes can get. 00:20:21.960 --> 00:20:23.820 How small can these QR codes get? 00:20:23.940 --> 00:20:29.160 For 12 words, you can use 21 by 21 points. And a large part of that, if you look 00:20:29.160 --> 00:20:34.090 at a QR code, there's these giant rectangles, right? So it's 21 by 21, including 00:20:34.090 --> 00:20:35.110 those giant rectangles. 00:20:38.290 --> 00:20:40.930 How small can QR codes get in general? 00:20:41.290 --> 00:20:42.310 21 by 21. 00:20:42.790 --> 00:20:44.730 Is that the smallest type of QR codes? 00:20:44.790 --> 00:20:49.750 I believe that is the smallest type of a regular QR code. There is also a micro 00:20:49.750 --> 00:20:55.050 QR standard that is even smaller, but that is useless for this purpose. So if you 00:20:55.050 --> 00:20:58.050 look at my book, maybe I'll just shamelessly shill that I have a book. 00:20:58.410 --> 00:21:00.410 We're shilling all the way in this episode. 00:21:00.590 --> 00:21:05.200 Bitcoin, a Work in Progress. Or just Google Bitcoin Sjors. You'll need to know 00:21:05.200 --> 00:21:05.900 how to spell that anyway. 00:21:06.080 --> 00:21:06.760 No one knows Sjors. 00:21:07.730 --> 00:21:13.250 That's all right. What was I saying? Yeah, so the book actually contains QR codes 00:21:13.250 --> 00:21:16.790 that will take you to various resources, right? So you don't have to type the 00:21:16.790 --> 00:21:20.790 whole URL. You scan the QR code. It takes you to a short URL. Those short URLs 00:21:20.790 --> 00:21:26.560 fit exactly into the smallest possible QR thing of the 21 by 21. So 00:21:26.560 --> 00:21:30.160 that's HTTP colon slash slash yadda yadda yadda. 00:21:30.710 --> 00:21:31.150 Okay. 00:21:31.270 --> 00:21:33.050 But you can also put a seed in it. 00:21:33.920 --> 00:21:39.300 So the smallest, at least the smallest sort of regular QR code is 21. Do you know 00:21:39.300 --> 00:21:40.220 what QR stands for? 00:21:40.720 --> 00:21:41.600 Quick response. 00:21:41.700 --> 00:21:47.440 Very well. Very good. So the smallest QR code is 21 by 21. And 00:21:47.440 --> 00:21:49.620 then there are bigger ones. 00:21:50.300 --> 00:21:53.920 Yeah. And so the reason you want to use bigger ones is, for example, because you 00:21:53.920 --> 00:21:55.740 have more words that you want to put into it. 00:21:55.900 --> 00:21:56.060 Right. 00:21:56.260 --> 00:22:00.840 So I think you need a 25 by 25 to have 24 words. And the other thing you can do 00:22:00.840 --> 00:22:06.170 is increase the error correction. And so what a QR code does is it shows you, a 00:22:06.170 --> 00:22:11.750 QR code starts with the actual thing that it's describing. So say a URL, a piece 00:22:11.750 --> 00:22:16.210 of text, and then it has a bunch of extra bits and a bunch of extra pixels. And 00:22:16.210 --> 00:22:20.910 their purpose is to basically help the device that's scanning it to correct for 00:22:20.910 --> 00:22:23.010 errors because the camera might not be accurate. 00:22:23.870 --> 00:22:28.760 Yeah, or, you know, your ink may be blurry. 00:22:28.930 --> 00:22:32.790 Yeah, so basically, you know, some people abuse this feature. They'll put the 00:22:32.790 --> 00:22:36.170 company logo in the middle of a QR code. And what that does is basically it 00:22:36.170 --> 00:22:39.970 obscures part of the QR code, but because it has so much error correction, you 00:22:39.970 --> 00:22:44.730 can actually obscure 5% or 10% of the QR code and still read it. That's the idea. 00:22:44.890 --> 00:22:49.150 We talked about error correction in an earlier episode, I believe, about this 00:22:49.150 --> 00:22:50.810 mempool sync project. 00:22:52.110 --> 00:22:52.670 Okay. 00:22:53.250 --> 00:22:53.670 Minisketch. 00:22:53.830 --> 00:22:58.430 I don't remember. Well, I kind of remember vaguely, but let's get back to the 00:22:58.430 --> 00:23:02.050 point. So we're using 21 by 21 QR codes. 00:23:02.450 --> 00:23:08.330 Or bigger. Yeah. The SeedQR standard uses several different sizes of 00:23:08.330 --> 00:23:08.770 QR codes. 00:23:08.930 --> 00:23:14.560 Right. And is there any sort of... I recall 00:23:14.560 --> 00:23:19.260 they're doing some tricks to actually make it fit. Is that not the case? 00:23:19.940 --> 00:23:25.520 Yeah, exactly. There are two ways to put the data into the QR code. One is a way 00:23:25.520 --> 00:23:31.370 that is as compact as possible. That's where you get to 21 by 21. The other is a 00:23:31.370 --> 00:23:35.730 way that other apps can actually read it. So the problem is when you use the most 00:23:35.730 --> 00:23:40.310 compact way to store it, there are not a lot of off-the-shelf applications that 00:23:40.310 --> 00:23:44.750 can actually read this QR code. So if you point your phone at it... If you use 00:23:44.750 --> 00:23:47.570 this very compact form, your phone will be confused. It won't understand what to 00:23:47.570 --> 00:23:51.350 do with the QR code. That's kind of a feature, actually, because you don't want it to. 00:23:53.010 --> 00:23:57.730 They've used optimizations that other apps don't understand. Is that the right 00:23:57.730 --> 00:23:58.330 way to put it? 00:23:58.330 --> 00:24:03.210 Basically, when you scan a QR code, your phone is generally expecting a URL or at 00:24:03.210 --> 00:24:08.250 least regular text. But these things will use full basically 00:24:08.250 --> 00:24:13.570 256-bit ASCII. So if you ever go... I don't know if you've ever seen 00:24:13.570 --> 00:24:17.290 some binary file and you open it up and it has all these symbols and your 00:24:17.290 --> 00:24:18.430 computer starts beeping at you. 00:24:18.650 --> 00:24:18.930 Yeah. 00:24:19.150 --> 00:24:23.530 Yeah. So that's basically what's in the QR code too. It's using all the bits it 00:24:23.530 --> 00:24:27.610 can. And so your phone thinking it's text will render complete gibberish. 00:24:28.850 --> 00:24:30.410 In fact, it will just not work. 00:24:30.770 --> 00:24:31.590 Right. Okay. 00:24:33.530 --> 00:24:35.150 But I think that's all solvable. 00:24:37.020 --> 00:24:40.880