WEBVTT 00:04.360 --> 00:06.020 I'm sorry I'm late. 00:08.630 --> 00:13.490 You know, yesterday a lot of people told me I was supposed to speak at 11 o'clock. 00:14.210 --> 00:19.410 And so I didn't actually look on the DEF CON website to see if that was actually true. 00:20.350 --> 00:22.690 So here I am at 11 o'clock. 00:25.010 --> 00:27.050 I'm sorry for the inconvenience. 00:39.080 --> 00:42.500 By the way, I don't mind if anyone takes my photos. 00:45.080 --> 00:52.300 Yeah, either John Callis, John Callis is CTO of PGP, or me, doesn't matter. 00:52.740 --> 00:54.680 We get photoed all the time. 00:55.220 --> 01:01.120 I figure I've already gotten in enough trouble with the Fed so it can't get any worse, right? 01:10.440 --> 01:11.840 Let's see if this comes up. 01:11.840 --> 01:12.520 Yep. 01:12.660 --> 01:16.500 Wow, that's a little bit lower resolution than usual, but that's alright. 01:21.060 --> 01:24.040 I'm going to... 01:27.860 --> 01:29.040 Okay. 01:29.040 --> 01:31.640 I'm going to demo my new project today. 01:31.640 --> 01:34.840 My new project is Secure VoIP. 01:36.880 --> 01:40.180 I think it's about time we had Secure VoIP. 01:40.760 --> 01:43.140 How many people here use VoIP? 01:44.100 --> 01:47.520 Oh, you guys are so geeky. 01:47.520 --> 01:49.240 The early adopters. 01:50.300 --> 01:50.920 Um... 01:52.960 --> 01:53.580 Well... 01:54.240 --> 01:55.240 You know... 01:56.140 --> 02:00.760 For years we've enjoyed the relative safety of the public switch telephone network. 02:00.760 --> 02:02.420 I say relative safety. 02:02.420 --> 02:04.940 I'm only speaking relative to the Internet. 02:05.500 --> 02:12.510 Of course, we all know that phone calls on the public switch telephone network can be intercepted. 02:13.720 --> 02:14.340 But... 02:16.120 --> 02:17.820 It's a lot harder to do. 02:17.820 --> 02:25.280 You have to be like the government or somebody who's willing to physically go to a place and clip on some alligator clips. 02:26.840 --> 02:32.320 Or you have to have access to the phone company or the cooperation of the phone company. 02:32.320 --> 02:49.200 But with VoIP, it's possible for somebody in Malaysia to hack into a machine somewhere and install a piece of software that will intercept all the VoIP calls on your network. 02:49.340 --> 02:52.340 And organize them like a TiVo player. 02:52.340 --> 02:54.340 And so... 02:55.780 --> 03:10.920 To move our precious phone calls from the sort of well-manicured neighborhood of the public switch telephone network to the sort of crime-ridden slum that is now the Internet, I think would be unwise without protecting it with encryption. 03:14.540 --> 03:15.100 So... 03:15.100 --> 03:19.380 First I'm going to do a little demo here and then I'm going to explain how it works. 03:21.060 --> 03:29.320 Somewhere in a soundproof booth is an accomplice who will now call me on my VoIP phone. 03:31.880 --> 03:33.980 Steve, call me. 03:36.940 --> 03:40.560 He said he's watching this, so he'll be able to tell. 03:41.180 --> 03:41.940 Yep, here it is. 03:41.940 --> 03:42.760 It's ringing. 03:42.760 --> 03:44.180 So now I'm going to answer. 03:45.040 --> 03:47.160 This is a regular SIP phone, by the way. 03:47.160 --> 03:48.640 You can call any other SIP phone. 03:49.940 --> 03:51.060 Great. 03:52.200 --> 03:53.260 Okay. 03:55.220 --> 03:57.360 I was afraid this would happen. 03:59.700 --> 04:03.420 Let me just say... I'm going to exit and relaunch. 04:04.820 --> 04:07.660 I'm using an open-source VoIP client. 04:08.560 --> 04:11.520 And then I added crypto to it. 04:11.720 --> 04:17.220 And so, there are some issues with the open-source VoIP client that I'm using. 04:19.380 --> 04:23.670 And sometimes it has difficulty with NAT firewall traversal. 04:25.110 --> 04:27.140 Okay, I'm ready again. 04:27.140 --> 04:30.630 Steve, I hope you've exited and relaunched. 04:32.320 --> 04:34.020 Call me again. 04:38.480 --> 04:39.710 What I did was... 04:40.560 --> 04:46.140 You know, many of you are aware of PGP Phone, a project that I did about nine years ago. 04:46.140 --> 04:48.920 At that time, the Internet wasn't ready. 04:49.180 --> 04:50.740 No one had broadband. 04:50.740 --> 04:54.720 There were no protocols that were standardized for VoIP. 04:54.840 --> 04:56.600 SIP wasn't invented yet. 04:57.560 --> 04:59.300 Steve, you're supposed to call me now. 05:07.090 --> 05:09.090 Maybe if I try calling him. 05:11.430 --> 05:12.930 Come on, Steve. 05:15.890 --> 05:16.370 Anyway... 05:16.870 --> 05:19.370 Oh, he's calling me on my cell phone. 05:19.810 --> 05:20.810 To tell me... 05:23.310 --> 05:24.270 Yes? 05:32.170 --> 05:34.250 You had to reboot your machine? 05:35.190 --> 05:36.590 Oh, man. 05:37.350 --> 05:39.110 That would explain a lot. 05:39.110 --> 05:39.730 Okay. 05:42.570 --> 05:43.530 Alright. 05:46.170 --> 05:48.510 Okay, I'll leave this open here. 05:49.210 --> 05:51.290 I'm going to put you on the little speakerphone. 05:52.770 --> 05:58.170 Okay, so you just yell into your speakerphone or into your phone whenever you want to talk to me. 06:01.410 --> 06:03.070 Or you could just call me. 06:04.270 --> 06:05.810 Okay, well, anyway... 06:05.810 --> 06:07.530 So, what I did was... 06:08.690 --> 06:12.370 Back in the days of PGP Phone, I had to improvise my own protocols. 06:12.370 --> 06:14.470 There was no SIP, there was no RTP. 06:14.770 --> 06:17.190 It was just the beginnings of RTP at that time. 06:17.190 --> 06:19.210 They were just starting to design it. 06:19.590 --> 06:24.010 And so I had to just sort of improvise my own. 06:24.150 --> 06:28.610 And it wasn't so bad for the time, but the Internet just wasn't ready. 06:28.610 --> 06:31.850 The bandwidth wasn't anywhere near what it had to be. 06:32.230 --> 06:37.550 So, it was a neglected product for many years. 06:37.830 --> 06:38.470 What? 06:39.530 --> 06:40.990 You ready to call? 06:44.700 --> 06:45.660 Okay. 06:46.660 --> 06:47.100 What? 06:47.100 --> 06:47.520 Okay. 06:47.520 --> 06:48.840 Just call when you're ready. 06:51.240 --> 06:55.940 So, fast forward nine years, and now the Internet is ready for this. 06:56.140 --> 06:58.460 Maybe this is not ready, but... 07:00.820 --> 07:05.960 So, there's still some NAT firewall traversal things in the open source VoIP plan. 07:05.960 --> 07:10.780 I'm using an open source VoIP plan called Stoom, which is written, oddly enough, in Python. 07:11.840 --> 07:14.860 And so, we had to write our crypto in Python. 07:15.340 --> 07:19.260 It's kind of a new experience to do that, to do a secure phone in Python. 07:19.260 --> 07:21.200 Or any kind of SIP phone in Python. 07:23.800 --> 07:27.660 And so, there are some problems with that. 07:27.660 --> 07:30.440 So, this is why... See, I didn't feel I was ready for this. 07:30.460 --> 07:36.320 But, Nico Sell persuaded me to unveil this at the Black Hat conference. 07:36.320 --> 07:37.940 And I said, no, no, I'm not ready. 07:38.140 --> 07:43.400 And so, she kind of, you know, kept pushing me to do it until finally I had to do it. 07:43.400 --> 07:46.280 Because the press started... 07:46.280 --> 07:47.000 What? 07:49.500 --> 07:50.920 Yeah, well, it's not. 07:54.500 --> 07:56.240 I would notice if it was. 07:57.860 --> 07:59.140 Oh, there it is. 07:59.940 --> 08:01.840 By the way, we don't have any audio. 08:03.040 --> 08:04.720 Oh, I didn't plug in the audio. 08:11.380 --> 08:13.780 Oh, it's... Just a minute. 08:14.220 --> 08:16.540 I'm gonna... We're gonna exit now. 08:18.120 --> 08:19.920 This is terribly embarrassing. 08:20.040 --> 08:23.880 This is the... You know, it worked the first time at Black Hat. 08:24.540 --> 08:26.700 When we were on an outside IP address. 08:26.700 --> 08:28.800 We couldn't get it to work inside the firewall. 08:28.800 --> 08:29.340 But... 08:30.340 --> 08:31.920 But we got some... 08:31.920 --> 08:34.280 But we got an outside IP address and it worked. 08:34.300 --> 08:36.200 Okay, now I'm ready, so call me. 08:37.100 --> 08:38.440 Oh, there we go. 08:42.630 --> 08:43.930 Oh, man, this is... 08:46.570 --> 08:48.010 This is not working. 08:49.310 --> 08:50.010 Okay. 08:50.290 --> 08:52.670 You know, the crypto is in pretty good shape. 08:52.670 --> 08:54.770 It's a good thing they gave me an hour to talk, right? 08:54.770 --> 08:56.610 So I can try this several times. 08:56.610 --> 09:00.430 I actually got here a little while ago and I wanted to test and test and test. 09:00.930 --> 09:04.110 But the Ethernet cable for this was right here at the podium. 09:04.110 --> 09:04.930 And so... 09:05.470 --> 09:07.070 I couldn't... 09:10.120 --> 09:11.960 Did you exit and relaunch? 09:15.440 --> 09:16.680 This is why I... 09:17.340 --> 09:19.860 This is why I never use... 09:19.860 --> 09:23.000 Why I never bring a laptop to a talk. 09:33.910 --> 09:36.090 All right, I'm gonna abort this. 09:36.090 --> 09:38.130 I'm just gonna explain how it works. 09:38.270 --> 09:38.930 Goodbye. 09:40.630 --> 09:41.390 Okay. 09:50.180 --> 09:52.900 Now I can get away from the... 10:10.390 --> 10:11.550 I'll just use this one. 10:12.350 --> 10:13.090 Okay. 10:14.950 --> 10:16.090 How humiliating. 10:16.690 --> 10:19.450 You have to believe me that it worked at Black Hat yesterday. 10:20.230 --> 10:21.690 I might try it again. 10:26.940 --> 10:27.900 Oh, yeah? 10:29.440 --> 10:30.580 It's tempting. 10:31.640 --> 10:34.300 If you want to bring it up here, maybe we can try it again. 10:37.880 --> 10:39.840 But do you have broadband? 10:41.360 --> 10:43.260 Okay, that's pretty impressive. 10:45.980 --> 10:47.460 All right. 10:48.920 --> 10:54.380 I looked at various other protocols that are currently being considered for secure VoIP. 10:55.440 --> 11:01.500 There is some IETF RFCs that define various ways of doing it. 11:01.500 --> 11:11.000 Most of them rely on external sources of a centrally controlled public key infrastructure with a certificate authority. 11:11.500 --> 11:16.700 I think that two people who want to talk to each other should not need permission from someone else to do it. 11:18.280 --> 11:22.060 And so I just do like I did with PGP Phone. 11:22.060 --> 11:24.000 I do a Diffie-Hellman key exchange. 11:31.480 --> 11:32.700 Yeah, okay. 11:32.700 --> 11:44.360 I do a Diffie-Hellman key exchange with hash commitment so that this means that I can read an authentication digest aloud that gets displayed. 11:44.360 --> 11:46.540 And the two people read it to each other. 11:46.540 --> 11:49.820 And if it matches, that means there's no man-in-the-middle attack. 11:50.140 --> 11:56.100 This eliminates the need for a certificate authority, a public key infrastructure. 11:56.160 --> 11:57.900 Boy, there's a lot of feedback here. 12:00.940 --> 12:01.740 The other way. 12:01.740 --> 12:02.560 Turn it the other way. 12:14.550 --> 12:17.230 Yes, I'm using a Macintosh. 12:19.130 --> 12:21.070 For security reasons. 12:26.220 --> 12:27.340 Yep. 12:28.080 --> 12:30.120 Alright, that's just not going to work. 12:36.520 --> 12:40.940 There are other approaches that don't use a public key infrastructure necessarily. 12:40.940 --> 12:52.240 They send SIP packets that use TLS connections and they put the session key right there in the SIP packet, not encrypted. 12:52.240 --> 12:54.960 They'll just send that, but they'll send it through a TLS connection. 12:54.960 --> 12:59.600 The problem is it's going through multiple TLS connections from server to server to server. 12:59.600 --> 13:05.300 And each one of them, it's decrypted and then re-encrypted in another TLS connection. 13:05.300 --> 13:12.920 So that means that each of those servers has access to the session key and is in a position to compromise the call. 13:13.480 --> 13:32.800 There's another scheme that actually takes the session key, encrypts it as an SMIME email message, and sticks that into the SIP packet and sends that to set up the call. 13:32.800 --> 13:38.760 And the other side receives it, decrypts it like it was a piece of email, extracts the session key, and then uses that. 13:39.440 --> 13:45.180 To use an email encryption standard... I mean, it's bad enough they're not using PGP for that, right? 13:45.460 --> 13:48.500 But even if it was PGP, I would still be complaining. 13:48.780 --> 13:50.480 Because it's just the wrong approach. 13:50.480 --> 13:55.140 You don't send an encrypted email to somebody to set up a phone call. 13:55.280 --> 13:58.320 It just feels wrong. 13:59.260 --> 14:07.780 And not only that, but it means that at the end of the call, you have persistent key material around that you can use to retroactively reconstruct the call. 14:07.780 --> 14:19.220 If somebody intercepted the call and recorded all the packets, they would be able to decrypt them after the fact if they could somehow later obtain the key that was sent through the SIP packet. 14:19.960 --> 14:23.000 In other words, it doesn't have perfect forward secrecy. 14:23.780 --> 14:30.100 Well, you know, I just can't imagine designing a secure phone that doesn't have perfect forward secrecy. 14:31.100 --> 14:37.180 Let's see, there's another one that has self-signed certificates, but you have to use a trusted server to get them. 14:37.520 --> 14:40.440 Or you don't know who they are, and it could be a man in the middle. 14:40.840 --> 14:44.760 So all of the other schemes that I looked at have problems. 14:45.600 --> 14:54.020 And almost all the problems come from trying to get somebody else involved in setting up a secure call between Alice and Bob. 14:54.500 --> 14:56.980 And it just seemed the wrong approach. 14:56.980 --> 15:01.740 So with my approach, just the two people are involved. 15:01.760 --> 15:05.320 It doesn't use anything involving another external server. 15:05.320 --> 15:08.860 It doesn't send anything in the SIP packet that relates to the crypto. 15:08.860 --> 15:17.580 Of course, it uses SIP to set up the call, like any SIP phone, but not to set up the encryption, not to set up the key agreement. 15:19.340 --> 15:29.480 Instead, you get the SIP call started, and then the RTP packets start flowing, and then it inserts a Diffie-Hellman exchange in the stream. 15:30.060 --> 15:37.160 Gets the key agreement, and then starts encrypting it using SRTP, secure real-time protocol. 15:37.980 --> 15:45.360 When I first started working on this, I thought I was going to have to encrypt my own packets with my own protocol, like I did with PGP Phone. 15:45.360 --> 15:53.420 But I discovered something called secure RTP, or SRTP, and I read the spec for it, and it looks a lot like PGP Phone. 15:54.020 --> 15:59.600 It encrypts the packets in a manner that is nearly identical to the way it was done in PGP Phone nine years ago. 15:59.600 --> 16:02.460 And I thought, this saves me a lot of trouble. 16:02.700 --> 16:04.720 I was going to do it this way already. 16:04.720 --> 16:07.540 So I'm going to use SRTP. 16:07.580 --> 16:13.140 This is actually one part of the protocol that is predefined in an RFC. 16:16.100 --> 16:20.460 But I do one more thing that I did not do in PGP Phone. 16:23.440 --> 16:32.240 At the end of the call, I erase all the keys, but I keep a hash of the shared secret that we used. 16:32.240 --> 16:35.900 I keep a hash of it around for the next phone call. 16:36.680 --> 16:48.800 And then when the next phone call happens, I do a fresh Diffie-Hellman key exchange, like I do with every call, but I also take one more step and mix in the retained shared secret from the last phone call. 16:49.660 --> 17:00.620 This means that there is sort of a key continuity model, which Peter Gutman, I see in the audience right here, he has called this the baby duck security model. 17:00.620 --> 17:02.540 He was referring to SSH. 17:02.820 --> 17:11.100 With SSH, you have an exchange of key material at the first session, and that's locally cached. 17:11.100 --> 17:15.720 And you assume that the man in the middle is not present in the first session. 17:16.080 --> 17:20.740 And if he's not present in the first session, it's too late for him to get involved in later sessions. 17:21.280 --> 17:23.780 Well, that's the same thing I'm using here. 17:25.120 --> 17:30.140 So, remember when I said about reading the hash aloud? 17:30.440 --> 17:32.360 Unfortunately, I can't show it to you. 17:33.780 --> 17:53.760 But, for those of you who have seen secure phones, like Eric Blossom's secure phone from back in the mid-90s, and the AT&T 3600, developed in the early 90s, they all involve displaying a short hash code that you read aloud to the other person to verify there's no man in the middle. 17:53.780 --> 18:03.420 Well, if you forget to do that, it's probably okay, because the attacker is afraid that you will do that, and so he won't attack. 18:03.720 --> 18:09.960 But, if he knows that you're lazy, he might be tempted to attack, knowing that you might not check it. 18:10.420 --> 18:15.340 But suppose you made 100 phone calls to your friend, and you didn't check. 18:15.340 --> 18:23.160 You just kept making phone calls, and you just forgot to check, or you were too lazy to check, by reading aloud the authentication digest. 18:23.860 --> 18:39.120 Well, if on the 50th call, you suddenly remember that, you know, I really ought to check this, and you read it aloud, and the other person reads it theirs aloud, and it checks, and it compares, and everything is good, it means that not only is this call secure, 18:39.120 --> 18:48.160 but every other call, all the way back in the previous 50 calls, to the first call you ever made to him, it proves that all of them were secure. 18:48.280 --> 18:51.660 It retroactively proves there was no man in the middle. 18:52.940 --> 18:55.500 That's really good for peace of mind. 18:55.620 --> 18:57.760 It means that you can be lazy most of the time. 18:58.280 --> 19:06.160 And then finally, one day, when you're diligent about it, your diligence assures you that all the other times you were lazy, it was okay. 19:06.780 --> 19:11.560 Of course, if it doesn't match, it means that there was a man in the middle all the way back to the beginning of time. 19:13.600 --> 19:16.020 That's a real, oh shit, moment, you know. 19:20.340 --> 19:28.620 But that's something that other secure phones don't do, and that my protocol does, and so I'm feeling pretty good about that feature. 19:30.080 --> 19:42.380 Now, if somebody were to kick the door in, and come in with guns, and pin you against the wall, and take your computer, and suck all the bits out of the computer, they're not going to be able to retroactively reconstruct the call. 19:42.460 --> 19:45.360 Not even with the retained shared secrets I just described. 19:46.020 --> 19:51.060 Because what doesn't actually retain the shared secret that was used in the call, it hashes it. 19:51.120 --> 19:53.260 So you can't go backwards in the hash. 19:56.480 --> 19:59.800 I'll be publishing a document describing this protocol. 20:00.280 --> 20:03.600 I think this is a better way to do secure void. 20:03.660 --> 20:12.440 This is a much better way than the other protocols currently being considered in various IETF RFCs. 20:12.440 --> 20:18.420 You know, designs tend to resemble the institutions that give birth to them. 20:18.660 --> 20:33.600 And I think that the centrally managed approaches that we're seeing right now sort of reflect the sort of institutional thinking that went into making them. 20:33.960 --> 20:39.720 And I tend to be more libertarian in my approach. 20:39.720 --> 20:44.200 I'm not a big L libertarian, but I'm a civil libertarian. 20:44.560 --> 20:52.200 But it's not only my political instincts, it's also, from a design perspective, simpler. 20:52.280 --> 20:57.440 To add a certificate authority to a SIP server adds immense complexity. 20:57.480 --> 21:03.500 We've seen many companies go bankrupt in the 1990s trying to build public key infrastructure. 21:03.860 --> 21:09.360 There are companies that try to create the technology for building certificate authorities. 21:09.720 --> 21:11.280 Those companies are now bankrupt. 21:11.380 --> 21:16.560 And sure, you can explain some of that by saying the internet bubble burst, but I don't think it's always from that. 21:16.560 --> 21:20.780 Some of them went bankrupt just because of the difficulty of building public key infrastructure. 21:20.880 --> 21:25.640 Not only the companies that were providing that technology, but the companies that were trying to use the technology. 21:25.880 --> 21:32.820 They didn't go bankrupt necessarily, but their IT departments almost went under trying to deploy public key infrastructure. 21:33.240 --> 21:38.780 So I think that if we were to learn from our mistakes, we should stop trying to do it that way. 21:38.780 --> 21:48.320 And when we have a new opportunity to deploy something with a new technology like VoIP, the last thing we should do is go back and take a proven technology. 21:48.320 --> 21:51.200 When I say proven, I don't mean proven successful. 21:51.200 --> 21:57.600 I mean a proven failure of public key infrastructure and try to apply it to VoIP. 21:58.100 --> 22:00.660 And so, my design doesn't do that. 22:03.400 --> 22:19.300 So, for those of you that would like to see this prototype work better than what we just witnessed, this thing is built around an open source VoIP client called Stoom, written in Python. 22:19.340 --> 22:22.460 And if you Google for Stoom, you can find the homepage for it. 22:22.580 --> 22:40.100 And for those of you who are Python weenies, if you go out and try to fix the open source VoIP client and make it work on all platforms, PC, Windows platforms too, and get it a little bit more stable, then this thing will benefit from that. 22:40.200 --> 22:51.560 All the problems that we just saw relate to the state machine in the VoIP client and how they interact with a firewall. 22:53.000 --> 22:56.320 So, I'd like to open it up for questions. 23:00.800 --> 23:01.760 Yeah. 23:13.910 --> 23:17.950 You're asking me to elaborate on my remark that PKI is a failure. 23:18.790 --> 23:21.730 Well, you know, I don't think PKI is completely a failure. 23:21.730 --> 23:25.290 I think it's actually worked pretty well for web browsers and web servers. 23:25.430 --> 23:30.950 I think SSL connections between your browser and the server seems to work pretty well. 23:34.030 --> 23:36.470 But it doesn't work that well for email. 23:38.530 --> 23:44.290 Well, the PGP PKI works a lot better for email. 23:45.270 --> 23:46.870 But, you know, take S-MIME. 23:47.230 --> 23:51.810 S-MIME is widely deployed and is in fact embedded in a lot of Microsoft products. 23:51.810 --> 23:54.190 I mean, bundled, I should say, with Microsoft products. 23:54.190 --> 23:55.250 And yet no one uses it. 23:55.250 --> 23:55.870 Why? 23:55.870 --> 24:00.370 Because to make S-MIME work, you have to have a PKI up and running already. 24:00.370 --> 24:02.870 So the activation energy is too high. 24:03.090 --> 24:05.730 With PGP, you can run right out of the box. 24:06.850 --> 24:10.030 You don't need a PKI to be running first. 24:10.170 --> 24:15.450 And I think that it would be crazy to try to burden VoIP with that same high activation energy. 24:17.010 --> 24:19.850 That's what I mean by PKI is a failure. 24:30.660 --> 24:33.840 Well, let's talk about how a man-in-the-middle attack would work. 24:36.320 --> 24:39.540 Let's imagine that this was actually in a hardware phone. 24:39.640 --> 24:42.900 You had a phone on your desk that did this protocol. 24:42.900 --> 24:45.820 And you bought that phone at Walmart for $100. 24:47.220 --> 24:50.920 So imagine that your friend also has a phone like that. 24:50.920 --> 24:54.720 And you want to call and it sets up a Diffie-Hellman exchange and now you're talking, right? 24:54.840 --> 24:59.580 But imagine that an eavesdropper went down to Walmart and bought two of these phones. 25:01.200 --> 25:04.840 And brought them home and set up the two phones side by side. 25:05.060 --> 25:10.100 And had one of the phones interposed between you and the other person. 25:10.100 --> 25:11.540 And the other phone too. 25:11.540 --> 25:18.500 So that when you're calling your friend, you're not actually calling your friend, you're calling this eavesdropper's phone right here. 25:18.500 --> 25:19.720 The one on the left. 25:21.240 --> 25:29.080 And the eavesdropper knows you're going to do this and has your friend's phone number on the speed dial on this phone here on the right. 25:29.800 --> 25:40.720 And so when he sees the phone ring and sees that you're calling and you're calling your friend, hits the speed dial, waits for your friend to answer, and as soon as your friend answers, he answers you. 25:40.720 --> 25:45.280 And now he's got these two phones and he holds the two phones together like this. 25:45.780 --> 25:48.840 So that the earpiece and the mouthpiece are connected. 25:49.140 --> 25:52.860 In this kind of sort of lewd and lascivious kind of connection there. 25:53.340 --> 26:00.580 And now you think you're talking to your friend, but in fact you're talking to the man in the middle. 26:00.580 --> 26:06.300 And the man in the middle can listen in the air gap between the two mouthpieces, whatever. 26:06.300 --> 26:14.160 And now notice that the eavesdropper didn't have to have any special knowledge of mathematics. 26:14.160 --> 26:16.960 Didn't have to know anything about how Diffie-Hellman works. 26:17.640 --> 26:24.480 The only important thing is that there's these two phones that they bought at Walmart, right? 26:24.560 --> 26:32.000 And now there's a random session key between you and one of the phones, and there's a different random session key between the other phone and your friend, right? 26:32.720 --> 26:41.480 Well, if you could figure out a way of discovering the fact that the two session keys aren't the same, you would know there was a man in the middle. 26:42.480 --> 26:52.520 Well, what if the two phones could hash the session key and display that on the little display, and you read it aloud to your friend? 26:52.580 --> 26:56.680 Well, they better match, because if they don't match, that means there's a man in the middle. 26:57.640 --> 26:59.180 And that's what we do here. 26:59.580 --> 27:00.980 Only I couldn't show it to you. 27:02.180 --> 27:03.800 It did work yesterday. 27:03.800 --> 27:05.380 I swear it worked yesterday. 27:05.780 --> 27:07.420 It's worked in a lot of places. 27:07.820 --> 27:12.200 But in some places, there's some firewall problems, and I can't get it to work. 27:12.600 --> 27:20.680 You know, a lot of the SIP phones out there have difficulty with firewall NAT traversal, but there's better protocols coming out all the time. 27:20.680 --> 27:26.780 You know, Skype does overcome these firewall problems, and I think we can overcome them in the SIP world, too. 27:29.780 --> 27:31.000 Back there. 27:34.490 --> 27:36.590 Could you yell really loud? 27:44.740 --> 27:50.580 No, unfortunately, it's written in Python, so it would have to be, you know, sort of refactored into C. 27:51.880 --> 27:56.320 The question was, can this code be ported to other open source clients? 27:56.840 --> 27:59.520 Yeah, but it has to be rewritten in C. 27:59.520 --> 28:02.440 In fact, I'm looking for volunteers to do that. 28:05.160 --> 28:08.020 I've actually got a series of products on the roadmap. 28:08.200 --> 28:10.420 You know, this is starting out just like PGP. 28:10.420 --> 28:15.260 Remember, PGP was started out as a private project without any money, you know. 28:15.360 --> 28:17.360 I paid for all this myself. 28:17.720 --> 28:18.980 Actually, I did get some help. 28:18.980 --> 28:23.640 Jeff Culver, who is well-known in the VoIP world, put in some of his own money, too. 28:23.720 --> 28:26.040 But most of it came from me paying. 28:26.040 --> 28:29.200 I hired an engineer full-time to work on it for a few months. 28:29.540 --> 28:33.100 But I was paying him, you know, really very low wages. 28:33.800 --> 28:38.580 And eventually, he had to take a job with a real company that paid him good money. 28:39.200 --> 28:43.520 So the development has slowed down. 28:43.520 --> 28:47.540 There is some development still going on with it, but it's at a slower pace. 28:48.880 --> 28:51.560 And I am going to try to start a company for this. 28:51.560 --> 28:55.360 And I'm actually talking to some investors to get some funding for this. 28:55.780 --> 29:00.880 And I got funding now from two sources so far. 29:00.880 --> 29:02.860 Jeff Culver put some of his own money in. 29:03.100 --> 29:05.400 And I got a little bit of money from Dick Clark. 29:05.960 --> 29:08.540 I don't mean the guy from American Bandstand. 29:08.980 --> 29:10.320 The other Dick Clark. 29:11.480 --> 29:13.600 Cyber security czar, you know. 29:13.600 --> 29:18.300 He left the Bush White House and wrote a book called Against All Enemies. 29:18.300 --> 29:20.880 It's a really good book, but anyway, it's too late now. 29:26.020 --> 29:29.020 So I'm going to start a new company and commercialize this. 29:29.340 --> 29:32.480 But I will publish the source code, because that's what I did with PGP. 29:33.100 --> 29:35.580 And I believe it's necessary to get people to trust it. 29:43.600 --> 29:45.120 So, more questions. 29:46.520 --> 29:47.260 Yeah. 29:52.480 --> 29:54.280 Could you yell really loud? 29:54.280 --> 29:56.260 Could you get up and just absolutely yell? 30:10.550 --> 30:12.750 You mean the retain shared secrets? 30:13.310 --> 30:15.510 You just need a little bit of memory for that. 30:24.280 --> 30:25.600 Yeah, okay, yes. 30:25.600 --> 30:29.400 You want to be able to take sort of an identity with you from one machine to another. 30:29.400 --> 30:31.500 Well, I've thought about doing that. 30:31.500 --> 30:37.000 You could put your configuration files in a USB drive and carry that around and copy it. 30:37.500 --> 30:39.420 But, I don't know. 30:39.420 --> 30:43.260 I think we'd have to do something more elaborate to do what you're talking about. 30:43.540 --> 30:49.520 Because, do you really want to copy that onto a computer in a cyber cafe, you know? 30:55.890 --> 31:01.390 Well, it's okay, because the first time you call somebody, there isn't any retained shared secrets. 31:01.390 --> 31:04.810 So, you just read the hash aloud and it just works. 31:05.350 --> 31:09.350 The retained shared secret feature is an extra feature. 31:09.370 --> 31:11.010 It kind of makes it nicer. 31:11.230 --> 31:13.030 But, it isn't necessary. 31:16.350 --> 31:17.490 Yes. 31:23.160 --> 31:24.720 Right, yes. 31:25.200 --> 31:26.060 That's right. 31:26.060 --> 31:28.020 I'm using SHA-256. 31:28.960 --> 31:30.760 SHA-256. 31:31.240 --> 31:32.380 Yes. 31:32.380 --> 31:38.060 And, for the Diffie-Hellman exchange, I'm using a 4000-bit Diffie-Hellman. 31:38.300 --> 31:49.340 And, for the block cipher, I'm using AES-256 running in counter mode, as defined by the SRTP protocol. 31:51.080 --> 31:55.180 So, I think I'm doing... I picked the right algorithms for this. 31:56.100 --> 32:07.810 And, actually, you know, even the collision problems that we've seen in some of the hash functions, I think, are not likely to be exploitable in the particular scenario that we're using them here. 32:07.970 --> 32:10.690 Even if I were using one of the weaker hash functions. 32:15.370 --> 32:16.790 John, do you want to say anything? 32:19.070 --> 32:19.770 Yeah. 32:19.990 --> 32:29.310 We've been working with Phil on this, too, and supporting him, and getting him contact with VCs, and I've been cajoling him into demoing at places like this, as well. 32:30.670 --> 32:31.330 Okay. 32:31.330 --> 32:44.830 I've been saying that, you know, we at PGP have been helping Phil with this, that we've been getting him with VCs, cajoling him to demo the thing, because I believe that getting some exposure to this is going to be important to get it properly funded and out there. 32:44.830 --> 32:50.070 The really important thing in what he's doing is that this will go nearly anywhere. 32:50.070 --> 32:55.630 I mean, it can go in a handset, it can go in a handheld computer, it can go on a laptop. 32:56.050 --> 33:02.790 The protocols are also directly layerable on top of what's going on. 33:02.790 --> 33:11.410 Sorry that we don't have a good network here to do the demo, but the system that he's running is an ordinary VoIP phone. 33:11.410 --> 33:14.110 You can call any other VoIP phone in the world with it. 33:14.110 --> 33:20.990 And it just so happens that if somebody else has one that has this security in there, poof, now all of a sudden you've got a secure phone call. 33:20.990 --> 33:31.110 And that's a really important aspect of what this does, because it means that the network effect of getting people to get secure phones is lower. 33:31.110 --> 33:42.530 That if you build a infrastructure that is a secure phone infrastructure that doesn't interoperate with regular phones, it makes it increasingly hard for people to go on because they have to make a decision. 33:42.530 --> 33:44.850 Do I want secure or do I want easy? 33:44.850 --> 33:54.390 Well, this gives you both easy and secure and other things like, you know, that you only really need to do the hash once or maybe even not do that. 33:54.390 --> 33:59.430 It's like I make phone calls all the time and I can tell from the person's voice whom I'm talking to. 33:59.690 --> 34:07.790 And you know from the sharing shared secret that you are talking to the end point that you were talking to last time. 34:08.190 --> 34:14.430 So, you know, if you have anything that tells you that that was a good phone call, you know that you are in the same state you were before. 34:14.430 --> 34:20.950 So again, this makes it be very easy and very understandable for people who are not crypto savvy, who are not security savvy. 34:20.950 --> 34:24.290 It can be put into all sorts of devices. 34:42.640 --> 34:43.560 That's right. 34:43.560 --> 34:47.600 The question is, what about a non-technical person using this phone? 34:47.940 --> 34:54.260 If your mother wants to use this phone, she doesn't have to read aloud the little hash digits that are displayed. 34:54.260 --> 34:56.880 She could just talk on the phone. 34:58.040 --> 35:00.340 The protocol would work the same way. 35:00.340 --> 35:03.700 The packets going back and forth are still, you know, the same kind of packets. 35:03.860 --> 35:10.040 It's just that final check that you do to verify to yourself, to assure yourself that there's no man in the middle, you would skip it. 35:10.260 --> 35:15.440 And presumably the man in the middle doesn't know that you're going to be lazy and you're going to skip it. 35:15.440 --> 35:18.380 So he's afraid to do his attack. 35:18.380 --> 35:19.420 It's an active attack. 35:19.420 --> 35:23.320 He has to actually sit in there and generate packets and inject them. 35:23.340 --> 35:29.860 He's going to be afraid to do that, because he's afraid he'll be discovered, because maybe your mom isn't as lazy as he thinks. 35:32.600 --> 35:39.680 One of the other advantages of this is that you know that if there is anybody listening to a phone call, they've always been there. 35:39.900 --> 35:45.640 So this also makes it very difficult for the attacker, because there is no way for them to get in and get out. 35:45.640 --> 35:51.760 They have to be in at the beginning and stay in, because the minute they drop out, they are also detected. 35:51.760 --> 35:59.840 This is a non-cryptographic security property that is very nice, because it serves as a real deterrent to the attacker. 35:59.840 --> 36:01.820 It makes their life really difficult. 36:04.380 --> 36:05.260 Yeah. 36:14.800 --> 36:22.840 Well, the question is, what happens if you try to call somebody who's using a regular POTS phone on the public switch telephone network? 36:24.560 --> 36:29.680 In that case, you would have to go through a gateway that connects the VoIP world to the PSTN world. 36:30.180 --> 36:34.560 And that means that you're not going to be able to make it a secure call end-to-end. 36:34.580 --> 36:39.380 Now theoretically, at least, you could make it a secure call between your phone and the gateway. 36:39.620 --> 36:41.780 Where it touches the PSTN. 36:41.780 --> 36:48.120 And then that last mile, hopefully it's only a mile, would be in the clear. 36:48.500 --> 36:53.320 But that gets you across the Atlantic, or across national borders. 36:57.500 --> 37:02.360 In the worst case, it's no less secure than a regular PSTN call. 37:02.360 --> 37:11.620 So that means that the new vulnerabilities that come from being in a VoIP world have been largely solved by this. 37:29.440 --> 37:31.420 The question is, the U.S. 37:31.420 --> 37:36.940 government is requiring people to put back doors in their VoIP software. 37:36.940 --> 37:39.340 I believe you're probably referring to CALEA. 37:40.220 --> 37:53.620 Well, they may change the way CALEA works, but I'm not a lawyer, and I don't have the most perfect understanding of this. 37:53.780 --> 38:00.140 But my limited understanding of CALEA is that it largely applies to the service providers. 38:00.220 --> 38:06.140 It largely applies to the people who have gateways to the PSTN, or the servers. 38:06.140 --> 38:11.140 I don't think it applies to end users. 38:11.880 --> 38:32.760 So if you're running some software on your laptop computer, and it sets up an encrypted link between you and the other party, without the involvement of the service provider, and you're not going through a gateway to the PSTN, then I'm going to go out on a limb here and suggest that CALEA doesn't apply to that case. 38:32.760 --> 38:37.240 Now it's possible that they could change the laws, make it more aggressive. 38:37.740 --> 38:41.080 But we'll have to worry about that when that happens. 38:50.850 --> 38:54.770 I haven't worked out the protocol to make this an anonymous system. 38:58.510 --> 39:03.310 It's peer-to-peer, unless you have to go through a proxy because of some firewall problems. 39:06.750 --> 39:13.970 Yeah, probably if you do the anonymous part, you're probably going to sacrifice your man-in-the-middle protection. 39:23.230 --> 39:25.950 There's not that much overhead for the encryption. 39:26.030 --> 39:38.350 The SRTP adds a little bit of extra to each packet for an HMAC, an authentication code, that gets stuck onto each packet. 39:38.350 --> 39:42.650 It's 80 bits long, but it can be shortened to 32 bits. 39:43.290 --> 39:47.350 And it's not that much of a bandwidth hit. 39:47.450 --> 40:02.710 And the only reason why that's there is actually not to encrypt it, but to authenticate, to prevent someone from sending in packets in a denial-of-service attack, so that the packets can be rejected because they don't authenticate. 40:02.750 --> 40:05.510 It's not actually necessary for the encryption. 40:06.350 --> 40:16.830 It's necessary, it's part of the extra protection you get from SRTP against a hacker coming in and injecting packets that aren't part of your phone call. 40:17.930 --> 40:19.770 I don't know if that's very clear. 40:19.950 --> 40:21.930 We can talk about it later if you want more details. 40:21.930 --> 40:26.110 Or go ahead and read the spec for SRTP, there's an RFC for it. 40:26.110 --> 40:29.730 It'll explain why you want to have that extra stuff. 40:33.390 --> 40:41.570 You know, it isn't only political reasons why I'm doing this. 40:41.570 --> 40:43.290 It's also business reasons. 40:43.410 --> 40:53.050 I think that if we're going to successfully migrate our phone calls to VoIP, to the internet, we're going to need this kind of protection. 40:53.810 --> 41:00.390 And in order to make a simpler design, I'm doing it this way. 41:01.290 --> 41:10.050 And so it isn't just my instincts for civil liberties, it's also my instincts for simple design. 41:10.190 --> 41:13.310 And the need for having secure calls. 41:14.790 --> 41:17.810 We need to protect critical infrastructure. 41:18.270 --> 41:19.990 And this is a good way to do it. 41:22.110 --> 41:25.630 That wasn't in response to any question, but I just wanted to add that. 41:26.590 --> 41:30.210 I don't want everybody to just think I do everything for political reasons. 41:33.310 --> 41:34.270 Yeah. 41:37.940 --> 41:41.820 Well, you know, the question is, what's the timing on the release of the source code? 41:41.820 --> 41:43.900 First, there has to be some source code. 41:44.720 --> 41:49.860 What you just didn't see is a demo of my prototype. 41:49.860 --> 41:50.560 It's a prototype. 41:50.560 --> 41:52.440 It's written in Python, you know? 41:52.440 --> 41:54.320 It's not the product. 41:55.000 --> 41:56.240 And it does work. 41:56.240 --> 41:57.520 I swear it works. 41:57.520 --> 41:59.240 It just doesn't work here. 41:59.240 --> 42:05.380 But what I want is a product where you can see. 42:06.140 --> 42:07.620 And there isn't one. 42:08.320 --> 42:11.220 To get one, I'm going to need funding. 42:11.700 --> 42:13.760 So I don't have a timetable for that. 42:13.760 --> 42:16.220 But what I might do, a lot of people have been asking me. 42:16.220 --> 42:21.920 I've gotten a tremendous number of requests to just release the prototype for people to play with. 42:22.400 --> 42:27.120 And for that, I'm looking at... I've got a whole lot of travel in August. 42:27.780 --> 42:30.560 And so I'm going to really try to get it out by the end of August. 42:30.560 --> 42:34.000 I actually considered trying to get it out yesterday for Black Hat. 42:34.340 --> 42:39.560 But I called a law office for... there's a lawyer I'm talking to about the export controls. 42:39.780 --> 42:43.280 Well, I had to file documents with the Commerce Department to tell them about it. 42:43.280 --> 42:46.900 Because, you know, there's still a little tiny bit of export controls left. 42:46.940 --> 42:51.460 I mean, we fought to get rid of the export controls in the 1990s. 42:51.520 --> 42:53.000 And we won. 42:53.000 --> 42:55.200 They got rid of the export controls. 42:55.340 --> 42:56.800 But there's just a little bit left. 42:57.400 --> 43:04.400 The only thing that you're required to do is that you just have to tell them about a product like this. 43:04.400 --> 43:06.120 You don't have to ask their permission. 43:06.120 --> 43:07.520 You just have to inform them. 43:07.520 --> 43:08.520 Well, I've done that. 43:08.520 --> 43:11.460 I've filed documents with them telling them about the product. 43:11.600 --> 43:15.940 But there's one other last vestigial remnant of the export controls. 43:15.940 --> 43:27.600 You're not allowed to export it to about six or seven countries like North Korea and Iran and Sudan and, you know, those countries. 43:27.600 --> 43:29.260 They're the embargoed countries. 43:29.260 --> 43:37.900 And so to put it on a web server, I have to put in special checks to make sure that it's not being downloaded by someone in one of those countries. 43:38.120 --> 43:40.460 And I don't know how to do that. 43:41.360 --> 43:45.520 And so I couldn't figure out how to do it in time for Black Hat yesterday. 43:45.940 --> 43:49.860 If I could have done it in time for Black Hat, you would have been able to download it today. 43:51.020 --> 43:56.280 If anybody wants to give me a hand on that, contact me and I'll put you to work. 43:57.060 --> 43:59.380 There's a lot of Unix weenies in here. 43:59.680 --> 44:06.120 And I'm sure that somebody in here can help me set up a server to do the reverse DNS lookups and all that kind of stuff. 44:06.880 --> 44:09.700 There's even some commercial packages that'll do it for you. 44:09.700 --> 44:11.520 But I don't want to have to pay for them. 44:16.870 --> 44:17.670 Yes? 44:18.550 --> 44:20.290 I've got to yell really loud. 44:20.290 --> 44:27.290 We've got this loud air conditioner and we've got a lawnmower and whatever else is going on. 44:27.290 --> 44:28.770 So I can't really hear you. 44:30.450 --> 44:31.210 Conference calls. 44:31.210 --> 44:32.710 What about conference calls? 44:35.130 --> 44:39.370 Well, in order to do a conference call, you would have to do one of these calls here. 44:39.370 --> 44:44.270 Just take this exact protocol and you'd have to do it between you and a server. 44:44.270 --> 44:49.070 And every other person who participates would all have to do it to the same server. 44:49.230 --> 44:51.350 The server would mix the audio together. 44:52.570 --> 44:54.670 And you've got to trust the server also. 44:55.270 --> 44:57.150 Which isn't so bad, you know. 45:00.810 --> 45:05.110 Now, each person would have a different encrypted Diffie-Hellman exchange. 45:05.730 --> 45:07.670 There would be a different session key. 45:08.150 --> 45:14.990 And the server would just treat them like they were all separate phone calls and then mix the audio together and distribute it back out. 45:14.990 --> 45:17.790 At least that's one way to do it. 45:25.320 --> 45:27.740 Alright, now let's not always see the same hands. 45:30.700 --> 45:32.480 Okay, well maybe I finished early. 45:34.260 --> 45:36.860 If you've got any other questions, you can ask me later. 45:37.520 --> 45:38.500 So what do you think? 45:38.500 --> 45:39.520 Is it going to work? 45:43.480 --> 45:45.960 I'd like to get your opinion about one thing. 45:45.960 --> 45:52.460 Is this going to... do you think that this is a better architecture than the other architectures? 45:52.460 --> 45:56.740 For those of you that have been reading about the encrypted VoIP approaches. 45:57.980 --> 45:59.140 What do you think? 46:14.230 --> 46:16.730 Oh hey, they opened up something in the firewall. 46:16.730 --> 46:18.870 We're going to try one more time to do the demo. 46:21.230 --> 46:22.730 Okay, alright. 46:25.600 --> 46:26.560 Just a minute. 46:26.560 --> 46:31.400 If you want to wait one more time and see another spectacular failure, just wait a second. 46:34.740 --> 46:35.620 What? 46:47.260 --> 46:48.920 Okay, I'm going to try calling them 47:00.560 --> 47:01.000 . 47:01.220 --> 47:02.440 Okay, you ready? 47:02.640 --> 47:03.360 You ready? 47:04.380 --> 47:06.100 Okay, let's see if this works. 47:16.560 --> 47:17.660 I did. 47:19.320 --> 47:21.120 You know, I hit the call button. 47:21.780 --> 47:23.220 We're not getting any evidence that... 47:25.580 --> 47:27.880 Okay, I'm going to hang up. 47:32.850 --> 47:34.310 Oh, incoming call. 47:36.270 --> 47:37.090 Unsecured call. 47:37.090 --> 47:38.070 Hey, it's secure. 47:38.070 --> 47:38.630 Hey! 47:39.110 --> 47:40.790 Look at that, going secure. 47:40.790 --> 47:42.090 But we have no audio. 47:57.400 --> 47:58.240 No audio. 47:58.240 --> 47:59.240 We're not getting any audio. 47:59.240 --> 48:03.520 Okay, what we're going to do is we're going to hold the microphone up to the little tiny speaker on here. 48:05.460 --> 48:07.620 Where's the... okay, yell it. 48:10.580 --> 48:11.420 Yell. 48:12.940 --> 48:14.220 Say something. 48:19.040 --> 48:21.900 I don't hear anything now. 48:24.420 --> 48:27.140 Yeah, okay, yes, there's sound coming out here. 48:27.540 --> 48:29.300 Alright, now listen to this. 48:29.380 --> 48:32.260 You see this secure button, this secure light here? 48:32.260 --> 48:32.940 Watch this. 48:32.940 --> 48:33.940 I'm going to press this. 48:33.940 --> 48:35.800 And this is what a wiretapper hears. 48:35.800 --> 48:38.100 This is a little Easter egg in the program. 48:38.240 --> 48:40.000 Okay, watch. 48:45.380 --> 48:50.260 That's taking the encrypted packets and playing them without decrypting them first. 48:52.440 --> 48:55.000 It sounds like white noise. 48:56.060 --> 48:57.680 I'm going to do that again. 48:58.280 --> 49:00.440 Wiretapper hears this. 49:01.680 --> 49:06.360 And that little staccato, you know, there's a lot of gaps there. 49:06.360 --> 49:09.760 It's because of jitter and bandwidth problems. 49:11.360 --> 49:16.700 Anyway, so encrypted text, encrypted voice sounds like white noise. 49:17.020 --> 49:19.280 So let them eat cipher text. 49:20.820 --> 49:25.660 And we have a go clear button here for the weenies here. 49:26.540 --> 49:30.420 And now it's just like making a normal plain text call. 49:30.440 --> 49:35.380 And if we hit go secure, it goes back to secure mode. 49:36.340 --> 49:39.180 Alright, but I'm sorry we have no audio. 49:54.420 --> 49:57.600 Say something, Steve, say something. 49:59.020 --> 50:01.220 No, no audio, sorry. 50:01.220 --> 50:02.060 No 50:08.320 --> 50:08.840 audio. 50:25.140 --> 50:28.000 Okay, so this is a secure call. 50:28.000 --> 50:30.300 Nobody can listen to this call. 50:31.620 --> 50:32.980 Say something. 50:34.440 --> 50:35.280 Hey, Phil, how you doing? 50:35.280 --> 50:36.600 You look great on TV. 50:36.900 --> 50:41.520 Alright, now I'm going to click that little indicator light that says secure. 50:41.520 --> 50:42.000 Alright 50:52.870 --> 50:55.830 , now we're going to actually... 50:55.830 --> 51:04.410 These buttons here, go clear and go secure, are not necessary in the real product, but we put them in because we're engineers and we like to fool around. 51:05.230 --> 51:07.630 So I'm going to say go secure here. 51:08.210 --> 51:11.630 And it does a little calculation for Diffie-Hellman. 51:11.650 --> 51:16.310 And now that little bong that you just heard is the bong that says you're now secure. 51:18.090 --> 51:18.890 Anyway. 51:20.090 --> 51:20.970 3U8. 51:21.630 --> 51:22.630 Oh, the hashes. 51:22.630 --> 51:24.650 Let's see, is there a man in the middle? 51:24.710 --> 51:27.430 I say 5SZ. 51:29.050 --> 51:29.930 3U8. 51:30.470 --> 51:31.010 3U8. 51:31.010 --> 51:31.790 That's right. 51:31.790 --> 51:33.350 There's no man in the middle. 51:34.450 --> 51:35.230 Alright. 51:35.750 --> 51:36.750 So it's great. 51:36.750 --> 51:39.310 No one knows what we're talking about. 51:39.410 --> 51:41.210 We have a secure call here. 51:41.210 --> 51:43.210 Do you have anything secret you want to tell me? 51:45.790 --> 51:46.530 Alright. 51:46.530 --> 51:47.650 So we're done. 51:47.650 --> 51:50.290 I'm going to hang up and that's it. 51:50.290 --> 51:51.150 See you later. 51:51.150 --> 51:52.050 Thanks, Steve. 51:53.270 --> 51:58.740 Alright, finally, we got it to work. 51:58.740 --> 51:59.940 We got it to work! 52:00.140 --> 52:01.880 I told you it worked. 52:02.580 --> 52:04.500 I wasn't just making this up. 52:13.420 --> 52:16.140 Oh, yeah, you had one more question? 52:16.860 --> 52:17.780 What? 52:23.300 --> 52:25.200 The open-source VoIP we're using...