1 00:00:00,300 --> 00:00:04,785 So, welcome to our lecture on Pubic Key Encryption where we're going to go back 2 00:00:04,785 --> 00:00:09,040 to confidentiality. And so, so here we go. 3 00:00:09,040 --> 00:00:12,253 If, if you recall we've been having these two topics that have been our theme 4 00:00:12,253 --> 00:00:15,445 throughout. just some[INAUDIBLE] . 5 00:00:16,980 --> 00:00:19,940 Oh sorry, I'm starting to, talk in route 13. 6 00:00:19,940 --> 00:00:23,880 Let's translate this back to non route 13. 7 00:00:23,880 --> 00:00:27,430 the terminology, the two kind of themes we've been following over the last couple 8 00:00:27,430 --> 00:00:31,390 of lectures and this lecture, are confidentiality and integrity. 9 00:00:31,390 --> 00:00:34,728 And confidentiality is hiding, right, shielding information. 10 00:00:34,728 --> 00:00:38,424 Not leaking information to people that you don't want to show it to. 11 00:00:38,424 --> 00:00:42,120 And integrity is making sure that you know who you're dealing with. 12 00:00:42,120 --> 00:00:45,540 And then the previous lecture, we really talked about kind of real light 13 00:00:45,540 --> 00:00:49,017 approachable ways of ensuring confidentiality with things like Caesar 14 00:00:49,017 --> 00:00:53,210 cipher. And then integrity using a simple message 15 00:00:53,210 --> 00:00:58,195 digest, that, based on a shared secret. So, the problem with all of those things 16 00:00:58,195 --> 00:01:02,300 that we just saw, is that they require a shared secret. 17 00:01:02,300 --> 00:01:06,510 And the problem in the world of the internet is, it's just really difficult. 18 00:01:06,510 --> 00:01:12,270 For every one of us before we establish well, before we can make any purchases or 19 00:01:12,270 --> 00:01:19,660 whatever at Amazon, that we somehow have to drive to Amazon headquarters. 20 00:01:19,660 --> 00:01:24,448 And, and get a shared secret from Amazon. Open up a book and say okay, hi Chuck, I 21 00:01:24,448 --> 00:01:28,800 see who you are and here's our shared secret, and you walk away. 22 00:01:28,800 --> 00:01:31,980 And as long as you carry that shared secret while you go. 23 00:01:31,980 --> 00:01:36,090 And if the shared secret is lost, it's difficult to review, revoke. 24 00:01:36,090 --> 00:01:41,127 So, as the internet and, and frankly in general, as security needed to be able to 25 00:01:41,127 --> 00:01:45,282 work at arms length. Meaning that you couldn't always bring 26 00:01:45,282 --> 00:01:47,705 everybody together and hand out shared secrets. 27 00:01:47,705 --> 00:01:51,190 And then have them go to the far reaches of the world and communicate. 28 00:01:51,190 --> 00:01:56,650 public key encryption was identified, as an extremely elegant solution to this 29 00:01:56,650 --> 00:02:00,651 problem. And so it was proposed by Diffie and 30 00:02:00,651 --> 00:02:05,320 Hellman in 1976. And it relies on two keys. 31 00:02:05,320 --> 00:02:08,670 It's asymmetric, meaning we're not using the same key to encrypt as decrypt, the 32 00:02:08,670 --> 00:02:12,370 way we were in the previous lectures. These are asymmetric. 33 00:02:12,370 --> 00:02:16,096 There is a public key, which is actually, does not need any protection whatsoever, 34 00:02:16,096 --> 00:02:20,008 and a private key. And the idea is they're generated inside 35 00:02:20,008 --> 00:02:22,073 of a computer. You generate the public key and the 36 00:02:22,073 --> 00:02:24,754 private key. You send out the public key, the public 37 00:02:24,754 --> 00:02:28,150 is used to do the encryption. And then private key is used to do the 38 00:02:28,150 --> 00:02:31,320 decryption. And they're related mathematically, in a 39 00:02:31,320 --> 00:02:35,322 way that's well understood, but difficult to compute for a key length that's large 40 00:02:35,322 --> 00:02:38,706 enough. So, there's a public key and a private 41 00:02:38,706 --> 00:02:41,114 key. So, I'd like you to take a look at this 42 00:02:41,114 --> 00:02:44,990 little video up on YouTube of Diffie, Hellman, and Merkle, the, the inventors 43 00:02:44,990 --> 00:02:50,040 of this. and I think it's a great video. 44 00:02:50,040 --> 00:02:54,380 I would love it if this were my video, but I didn't produce this video. 45 00:02:54,380 --> 00:03:03,430 So so take a quick look. So, one of the things about this public 46 00:03:03,430 --> 00:03:07,005 private key encryption is now that we know about it, it's like wow, it's pretty 47 00:03:07,005 --> 00:03:10,328 obvious. And frankly Caesar and the Germans and 48 00:03:10,328 --> 00:03:14,260 everybody could have used this idea. They just hadn't thought of it yet. 49 00:03:14,260 --> 00:03:17,484 And the other thing that's kind of interesting if you look into the story of 50 00:03:17,484 --> 00:03:21,020 this, is that the first reaction people got when they started thinking about this 51 00:03:21,020 --> 00:03:25,979 is like it can't be this easy. Now, it's sort of both easy and hard but, 52 00:03:25,979 --> 00:03:29,159 but the concept is real elegant and really beautiful, and that is that we 53 00:03:29,159 --> 00:03:33,390 have this public key. So, the public key is part of a public 54 00:03:33,390 --> 00:03:36,750 private pair, and it's used to do the encryption. 55 00:03:36,750 --> 00:03:40,726 The beautiful, beauty is it's computation and difficult to recover that private key 56 00:03:40,726 --> 00:03:43,945 from the public key and the encrypted text. 57 00:03:43,945 --> 00:03:49,156 A key thing is, is it's not impossible. And that's kind of one of the interesting 58 00:03:49,156 --> 00:03:52,439 philosophies of security that, that we started at the very beginning in talking 59 00:03:52,439 --> 00:03:55,920 about security. The perfect security is kind of 60 00:03:55,920 --> 00:04:01,040 impossible to achieve, unless you simply don't send anything. 61 00:04:01,040 --> 00:04:05,396 And so, public private key, asymmetric keys is, is well understood as to how you 62 00:04:05,396 --> 00:04:09,290 would break it. Everyone knows how to break it. 63 00:04:09,290 --> 00:04:12,218 The problem is, is that computers aren't fast enough to break it, and when 64 00:04:12,218 --> 00:04:15,540 computers get faster we'll just make the keys bigger. 65 00:04:15,540 --> 00:04:19,430 So, the mathematics of this makes it impractical to break. 66 00:04:19,430 --> 00:04:24,050 I mean literally impractical to break. Now I think we can safely assume that, 67 00:04:24,050 --> 00:04:27,590 governments probably have enough computation to crack these once in a 68 00:04:27,590 --> 00:04:31,045 great while. I mean, they're not cracking every 69 00:04:31,045 --> 00:04:34,929 transaction between you and target when you want to buy something. 70 00:04:34,929 --> 00:04:38,859 But if they really have to, they can record the encrypted transmissions. 71 00:04:38,859 --> 00:04:42,269 And if they really had to and took a long time, I have no idea how long it would 72 00:04:42,269 --> 00:04:46,375 be, they can break it. So, that's actually kind of a neat way to 73 00:04:46,375 --> 00:04:49,538 think about this. By revealing it all, frankly, any 74 00:04:49,538 --> 00:04:53,686 computer scientist could make a name for them their whole life if they proved that 75 00:04:53,686 --> 00:04:59,112 there was something wrong with this. By revealing the algorithm, revealing the 76 00:04:59,112 --> 00:05:02,596 cracking technique, if someone can come up with a better cracking technique, it 77 00:05:02,596 --> 00:05:07,588 is like, fame and glory forever. Which means that, we're pretty sure that 78 00:05:07,588 --> 00:05:10,864 there's no good way to crack this other than the brute force mechanism, that 79 00:05:10,864 --> 00:05:17,873 requires a large amount of computation. So, if you're going to use public private 80 00:05:17,873 --> 00:05:22,145 key encryption, you have to generate a pair. 81 00:05:22,145 --> 00:05:27,540 And it starts by charging, choosing two really large random numbers, with 82 00:05:27,540 --> 00:05:33,520 hundreds if not thousands of digits that are prime. 83 00:05:33,520 --> 00:05:36,411 See you kind of choose a, choose a random number really big. 84 00:05:36,411 --> 00:05:39,419 And then you kind of look around for a nearby prime number and you choose two of 85 00:05:39,419 --> 00:05:43,330 those. And then you multiply them, okay? 86 00:05:43,330 --> 00:05:47,460 Getting an even larger number. And then, through some steps, through 87 00:05:47,460 --> 00:05:50,760 some calculations, you compute the public and the private keys from that large 88 00:05:50,760 --> 00:05:53,976 number. The essence of this, are those two prime 89 00:05:53,976 --> 00:05:56,426 numbers. Prime numbers of course are numbers that 90 00:05:56,426 --> 00:06:00,360 you only divide by themselves and one which means they have no factors. 91 00:06:00,360 --> 00:06:03,500 Which means they're kind of like looking for a needle in a haystack. 92 00:06:03,500 --> 00:06:07,410 And so the public and private key is really based on these two prime numbers. 93 00:06:07,410 --> 00:06:11,660 If you could figure out what the prime numbers were, you'd be okay. 94 00:06:11,660 --> 00:06:14,300 But the computational difficulty is finding the prime numbers that are 95 00:06:14,300 --> 00:06:19,160 extremely large, and finding the right prime numbers that are extremely large. 96 00:06:19,160 --> 00:06:23,380 So, it's easy to do some calculations in one direction, but not in other. 97 00:06:23,380 --> 00:06:25,250 So, for example, what are the factors of 55,124,159? 98 00:06:25,250 --> 00:06:29,799 Quick. But if I simply ask you what do you 99 00:06:29,799 --> 00:06:38,334 multiply 7,919 to get that 55 million number. 100 00:06:38,334 --> 00:06:40,870 That's easy. You do a division. 101 00:06:40,870 --> 00:06:46,596 And it turns out that you can find out 6961 really easy, right? 102 00:06:46,596 --> 00:06:51,604 So, if I just say what are these two numbers? 103 00:06:51,604 --> 00:06:54,996 That's hard. If I say given this number, what's the 104 00:06:54,996 --> 00:06:57,700 other number? That's trivial. 105 00:06:57,700 --> 00:07:01,122 So, you can think of this as, the decryption is where the receiver of the 106 00:07:01,122 --> 00:07:04,671 message knows kind of half of the calculation. 107 00:07:04,671 --> 00:07:07,600 Where as the world doesn't know either half of it. 108 00:07:07,600 --> 00:07:10,990 Doesn't know the calculation, so has to figure out both halves. 109 00:07:10,990 --> 00:07:13,790 Whereas the receiver only has to figure out one half. 110 00:07:13,790 --> 00:07:18,212 And so that's how asking the question of what are the factors, versus given one, 111 00:07:18,212 --> 00:07:22,115 what's the other. So it, it takes a problem that's easy, 112 00:07:22,115 --> 00:07:24,966 makes it computationally nearly impossible. 113 00:07:24,966 --> 00:07:27,325 But again, not impossible, just nearly impossible. 114 00:07:27,325 --> 00:07:33,746 Okay, so here's the notion. So, you're about to type your visa card 115 00:07:33,746 --> 00:07:38,520 into a credit card into like Amazon's web page. 116 00:07:38,520 --> 00:07:43,070 And so what happens is, is that Amazon will has a public key and a private key. 117 00:07:43,070 --> 00:07:46,510 That they retain. And they will send you the public key 118 00:07:46,510 --> 00:07:50,035 across a medium, the internet. They're going to send this to you 119 00:07:50,035 --> 00:07:54,264 somehow. But the bad guys, Eve, or Charlie or 120 00:07:54,264 --> 00:07:59,584 whoever they are. The bad guys. 121 00:07:59,584 --> 00:08:04,590 This is Alice and Bob. Eve and Charlie are always looking. 122 00:08:04,590 --> 00:08:07,770 So, Eve and Charlie could intercept it. And you assume that they can. 123 00:08:07,770 --> 00:08:10,780 This is the key. Don't, don't try to pretend they can't. 124 00:08:10,780 --> 00:08:12,560 Even though it's very difficult for them to do it. 125 00:08:12,560 --> 00:08:15,725 But you assume they can. So, the public key comes across. 126 00:08:15,725 --> 00:08:19,885 It is simply sent to you as part of the beginning of establishing a sur, secure 127 00:08:19,885 --> 00:08:26,070 connection. And the bad guys see it too, or girls. 128 00:08:26,070 --> 00:08:28,840 They see it too. So, the public key comes to you. 129 00:08:28,840 --> 00:08:34,080 And then what you do, is you encrypt, using that public key. 130 00:08:34,080 --> 00:08:37,178 And create some encrypted text, cipher text. 131 00:08:37,178 --> 00:08:41,168 Which you then send back across the danger, where Eve and Charlie are 132 00:08:41,168 --> 00:08:44,588 watching. And it comes across, they intercept the 133 00:08:44,588 --> 00:08:47,695 encrypted text. They've intercepted the public key. 134 00:08:47,695 --> 00:08:54,640 And they, they can try as hard as they like with supercomputers to derive this. 135 00:08:54,640 --> 00:08:57,853 And frankly, like I said, if they had months and months and months and really 136 00:08:57,853 --> 00:09:01,975 fast computers, they could. Okay, but because Amazon is in sole 137 00:09:01,975 --> 00:09:06,415 possession of private key and it never left Amazon servers. 138 00:09:06,415 --> 00:09:10,760 It is a very simple matter for Amazon to decrypt and get your plain text. 139 00:09:10,760 --> 00:09:14,510 It happens, very quickly. Just like if you kind of know half of the 140 00:09:14,510 --> 00:09:17,644 prime number calculation. Figuring out the other prime number is 141 00:09:17,644 --> 00:09:21,131 really, really easy. Okay, so, so again, these people see all 142 00:09:21,131 --> 00:09:25,883 of this information, and yet it's computationally virtually impossible, for 143 00:09:25,883 --> 00:09:31,478 all practical purposes, to do it. And so it's beautiful, because there was 144 00:09:31,478 --> 00:09:35,308 no need to protect the public key. We never had to get in the same room, and 145 00:09:35,308 --> 00:09:38,619 away it goes. So you just, Amazon just blasts out it's 146 00:09:38,619 --> 00:09:41,880 public key and we encrypt using Amazon's public key. 147 00:09:41,880 --> 00:09:45,628 We can't decrypt it but we don't need to decrypt it. 148 00:09:45,628 --> 00:09:49,880 All we need to do is send it to Amazon and voila, it works. 149 00:09:49,880 --> 00:09:53,540 So, the beautiful thing is the public keys can be distributed, they can be 150 00:09:53,540 --> 00:10:00,737 intercepted and it does not matter. So, with this notion of public private 151 00:10:00,737 --> 00:10:08,510 key encryption in general, we made a change to HTTP. 152 00:10:08,510 --> 00:10:11,530 A layer, a mini layer is in the data model. 153 00:10:11,530 --> 00:10:15,400 If you remember way back, perhaps you've even forgotten about the layered model. 154 00:10:15,400 --> 00:10:21,320 Remember that layered model? Application, transport, Internet. 155 00:10:21,320 --> 00:10:25,400 Remember this is sort of one computer and this is the other computer. 156 00:10:25,400 --> 00:10:28,648 These are their routers, routers. These are the hops. 157 00:10:28,648 --> 00:10:30,760 There's like 15 of these. Remember? 158 00:10:30,760 --> 00:10:33,735 Remember all this? So, it comes back now to haunt us. 159 00:10:33,735 --> 00:10:36,961 Okay. So, if you recall, just sort of to, to 160 00:10:36,961 --> 00:10:40,825 briefly remember that, the transport layer is responsible for the 161 00:10:40,825 --> 00:10:45,534 retransmission. It gives us the appearance of a reliable, 162 00:10:45,534 --> 00:10:50,490 ordered connection between the, our application and the far application. 163 00:10:51,550 --> 00:10:57,095 HTTP is one of the application protocols. and so there is a little mini layer that, 164 00:10:57,095 --> 00:11:03,069 that is layered in, sort of seamlessly on top of the transport layer. 165 00:11:03,069 --> 00:11:09,030 That basically takes plain text and encrypts it and turns it into ciphertext. 166 00:11:09,030 --> 00:11:12,815 And then ciphertext on the way out turns it back into plain text. 167 00:11:12,815 --> 00:11:15,700 Okay. And so what happens is, is these 168 00:11:15,700 --> 00:11:19,850 applications just send plain text. And out comes plain text. 169 00:11:19,850 --> 00:11:23,480 And there's a little bit of extra glue in the middle here, that's sort of a secure 170 00:11:23,480 --> 00:11:28,524 transport, secure sockets layer. This is, this thing here is often called 171 00:11:28,524 --> 00:11:33,280 a socket, oop, SOCK. It'd be good if I could spell socket. 172 00:11:33,280 --> 00:11:38,330 So, this is a socket, and then the red part is a secure socket. 173 00:11:38,330 --> 00:11:41,330 So, the applications kind of don't encrypt the data at all. 174 00:11:41,330 --> 00:11:45,590 There's a library that encrypts it. And the other thing is, is that all the 175 00:11:45,590 --> 00:11:49,430 rest of the internet, the internet, the link layer, the routers nothing, the 176 00:11:49,430 --> 00:11:53,650 Ethernet, the fiber. They don't even know the difference 177 00:11:53,650 --> 00:11:57,514 between encrypted text or non encrypted text, because the encrypted text wanders 178 00:11:57,514 --> 00:12:01,820 around fully encrypted. Addresses are not encrypted. 179 00:12:01,820 --> 00:12:05,192 And so it stays encrypted all the way through the entire network. 180 00:12:05,192 --> 00:12:09,665 It actually, if you then think about the fact that, this is the moment that it 181 00:12:09,665 --> 00:12:15,054 leaves your computer. The only thing, so the plain text comes 182 00:12:15,054 --> 00:12:18,130 in here, gets encrypted here, encrypted comes down. 183 00:12:18,130 --> 00:12:21,480 The only thing that leaves your computer is encrypted text. 184 00:12:21,480 --> 00:12:24,627 And it makes it all the way across. The encrypted text goes into Amazon, so 185 00:12:24,627 --> 00:12:27,980 this is Amazon. This is you. 186 00:12:29,130 --> 00:12:32,315 The encrypted text finds its way through all these things. 187 00:12:32,315 --> 00:12:36,670 And it come in encrypted. And it actually doesn't get encrypted, 188 00:12:36,670 --> 00:12:39,920 until it's sort of right at the point where Amazon's web server that's going to 189 00:12:39,920 --> 00:12:46,799 actually charge your credit card. So, this is actually beautifully elegant. 190 00:12:46,799 --> 00:12:52,532 In that, the rest of the network is blissfully unaware, that any encryption 191 00:12:52,532 --> 00:12:56,230 is happening. It's just moving the data. 192 00:12:56,230 --> 00:12:58,764 So, this did not require any change. Again the beauty of the layer of 193 00:12:58,764 --> 00:13:01,194 architecture. Did not require any change, sort of below 194 00:13:01,194 --> 00:13:04,003 the transport layer. And as a matter of fact, all of the 195 00:13:04,003 --> 00:13:07,565 sequencing and re-transmission that happens in the TCP layer. 196 00:13:07,565 --> 00:13:12,060 That happens with the encrypted stuff too because it's just encrypted. 197 00:13:12,060 --> 00:13:14,472 It's just text. It's gibberish text, it's not the 198 00:13:14,472 --> 00:13:17,290 original visa card number that you're sending. 199 00:13:17,290 --> 00:13:22,340 You're sending 123 and out comes, you know, wxy, the wxy just goes. 200 00:13:22,340 --> 00:13:26,010 It's re-transmitted. All this crap just works, it's like, 201 00:13:26,010 --> 00:13:28,150 beautiful. It's a beautiful thing. 202 00:13:28,150 --> 00:13:32,502 It's absolutely a beautiful thing. Then it's just like this mini layer kind 203 00:13:32,502 --> 00:13:36,340 of between, it's like the top slice of the transport layer. 204 00:13:36,340 --> 00:13:39,207 That's how I'm drawing it right here. It's like this little kind of top extra 205 00:13:39,207 --> 00:13:42,151 little thing, that says you know what, we're going to transport, actually help 206 00:13:42,151 --> 00:13:45,619 me out and give me some encryption while we're at it. 207 00:13:45,619 --> 00:13:47,720 And there's all kinds of cool stuff that goes back and forth. 208 00:13:47,720 --> 00:13:49,873 The public and private keys get exchanged. 209 00:13:49,873 --> 00:13:52,230 That's all kind of stuff we don't worry about. 210 00:13:52,230 --> 00:13:55,735 We just send data and get data back. Pretty cool, huh? 211 00:13:55,735 --> 00:14:00,949 So, this really solves the problem of the fact that we basically should assume, 212 00:14:00,949 --> 00:14:07,740 that everything between our computer and the destination computer. 213 00:14:07,740 --> 00:14:11,480 This is you. This is Amazon, right? 214 00:14:12,820 --> 00:14:16,903 Everything here, this is all dangerous. There's some like, terrifyingly scary 215 00:14:16,903 --> 00:14:21,390 individual, that's watching everything, doing packet sniffing. 216 00:14:21,390 --> 00:14:25,929 This might be Eve the eavesdropper. This looks like a little he, he looks 217 00:14:25,929 --> 00:14:28,160 pretty tough. Right. 218 00:14:28,160 --> 00:14:30,280 And, and so that even the wireless, right? 219 00:14:30,280 --> 00:14:33,270 This is the wiFi connection. The WiFi is dangerous. 220 00:14:33,270 --> 00:14:36,200 Now, the reality is, is these things aren't all that dangerous. 221 00:14:36,200 --> 00:14:39,140 The WiFi's probably the weakest link of these whole thing. 222 00:14:39,140 --> 00:14:41,610 But we have to assume that it's dangerous, right? 223 00:14:41,610 --> 00:14:45,027 We, we want to assume that the only thing that's safe, and unfortunately if you put 224 00:14:45,027 --> 00:14:49,410 viruses in your computer then they can get at the plain text. 225 00:14:49,410 --> 00:14:54,260 If Amazon loses its data somehow, then they get the plain text, right? 226 00:14:54,260 --> 00:15:00,410 But, but basically, you know, we want to distrust all of this, okay? 227 00:15:00,410 --> 00:15:05,302 So, this concept is called Transport Layer Security. 228 00:15:05,302 --> 00:15:09,540 Also called SSL. Also known as HTTPS. 229 00:15:09,540 --> 00:15:14,230 HTTPS for secure, and it's kind of like between the TCP layer and the application 230 00:15:14,230 --> 00:15:17,878 layer. Or the top half of the TCP layer is the 231 00:15:17,878 --> 00:15:22,770 way I like to think about it. It's because it's based on public private 232 00:15:22,770 --> 00:15:26,211 key encryption it's, difficult but not impossible. 233 00:15:26,211 --> 00:15:30,111 Normal people don't have the kind of equipment to break it, even governments, 234 00:15:30,111 --> 00:15:34,124 if they can break it, I don't know I'm not an expert. 235 00:15:34,124 --> 00:15:38,024 I don't hang out with the government, so I don't really know but, assume that if 236 00:15:38,024 --> 00:15:42,682 they really put their mind to it, in a very narrow situation. 237 00:15:42,682 --> 00:15:47,280 If you become really interesting, they will find your credit cards. 238 00:15:47,280 --> 00:15:51,966 Probably there's easier ways to get your credit cards, than by decrypting your 239 00:15:51,966 --> 00:15:56,610 text. So, it's hard to decrypt. 240 00:15:56,610 --> 00:15:59,834 And as I mentioned, because of the layered architecture, the TCP layer, IP 241 00:15:59,834 --> 00:16:06,066 and Link layers are completely unaware. So, you'll, you, you see this in the form 242 00:16:06,066 --> 00:16:10,301 of URLs that start with HTTPS. [SOUND]. 243 00:16:10,301 --> 00:16:11,907 Right, they start with HTTPS. Dub dub dub facebook.com versus HTTP. 244 00:16:11,907 --> 00:16:19,267 And there was a time a few years back where you know, they were, it used to be 245 00:16:19,267 --> 00:16:28,240 a little more expensive inside of the servers to do HTTPS. 246 00:16:28,240 --> 00:16:31,384 It still is. And so some sites would try to do some of 247 00:16:31,384 --> 00:16:35,060 their activity without using secure protocols. 248 00:16:35,060 --> 00:16:39,131 And others would use use, use non secure and secure and then flip you back and 249 00:16:39,131 --> 00:16:41,860 forth. Like if you're typing your password. 250 00:16:41,860 --> 00:16:45,760 The problem was is that there is actually still sensitive data being sent. 251 00:16:45,760 --> 00:16:49,388 Even across the insecure. And there was a, quite a famous, thing 252 00:16:49,388 --> 00:16:53,090 where people could install a Firefox plug in. 253 00:16:53,090 --> 00:16:58,182 And watch Facebook, non secure Facebook things go back and forth across, like, a 254 00:16:58,182 --> 00:17:01,160 Starbucks. And it would just show you all the 255 00:17:01,160 --> 00:17:04,168 people's Facebook accounts. And you could log in as them and post as 256 00:17:04,168 --> 00:17:06,760 them. And so you've seen a situation where 257 00:17:06,760 --> 00:17:10,940 companies are just starting to use HTTPS for everything. 258 00:17:10,940 --> 00:17:15,280 You, as a user, have to be aware to see if you're typing anything sensitive, 259 00:17:15,280 --> 00:17:19,780 never type it into a URL that doesn't say HTTPS. 260 00:17:19,780 --> 00:17:20,620 'Kay? Never do that. 261 00:17:20,620 --> 00:17:24,750 You're typing in a password, a credit card number, any kind of personal 262 00:17:24,750 --> 00:17:28,751 information. Make sure you're doing HTTPS, and make 263 00:17:28,751 --> 00:17:33,047 sure that, that you know what it is. We'll talk about that in a bit, we'll 264 00:17:33,047 --> 00:17:35,090 talk a little bit more about that in a bit. 265 00:17:35,090 --> 00:17:38,570 So, so if we take a look and we think about where the bad guys are it, the bad 266 00:17:38,570 --> 00:17:44,324 guys are kind of everything. And this secure TCP runs, is the one part 267 00:17:44,324 --> 00:17:49,238 of the layer of our architecture that runs from within your laptop to within 268 00:17:49,238 --> 00:17:53,740 the server. And so, then, if we kind of assume the 269 00:17:53,740 --> 00:17:57,650 worst. The, the, the backbone is pretty safe. 270 00:17:57,650 --> 00:18:02,097 The wiFi is probably the most dangerous. Alright, but when we do secure system 271 00:18:02,097 --> 00:18:08,097 TCP, secure system to system TCP. We are doing the encryption, right here 272 00:18:08,097 --> 00:18:13,585 inside your computer before it leaves. And we're only doing the encryption right 273 00:18:13,585 --> 00:18:17,000 when it comes back in the computers. So, the decryption and encryption are 274 00:18:17,000 --> 00:18:20,558 happening inside of Amazon's computer and inside your computer. 275 00:18:20,558 --> 00:18:24,960 And nothing else. So, Secure Sockets is pretty good. 276 00:18:24,960 --> 00:18:28,494 Now the place where you're still in danger, is there might be a virus that's 277 00:18:28,494 --> 00:18:32,394 watching your keystrokes, right. This is why virus checking is so 278 00:18:32,394 --> 00:18:35,241 important. Because at some point, you're typing it 279 00:18:35,241 --> 00:18:39,085 into your computer and the, and the greatest danger you have to losing your 280 00:18:39,085 --> 00:18:43,970 data is really two things. One, that you've got a virus. 281 00:18:43,970 --> 00:18:51,300 Or B, somebody has redirected you not to talk to evil Amazon instead of Amazon. 282 00:18:51,300 --> 00:18:54,990 And that's what we'll talk about in the next lecture. 283 00:18:54,990 --> 00:18:58,730 How to know, how do these browsers really know they're talking to the real Amazon? 284 00:18:58,730 --> 00:19:03,179 And that is not confidentiality. Confidentiality is stopping the bad guy 285 00:19:03,179 --> 00:19:07,240 from seeing what you're sending. As they're eavesdropping. 286 00:19:07,240 --> 00:19:09,580 Eve is eavesdropping. Okay? 287 00:19:10,840 --> 00:19:15,384 Now, the next thing is the question of is this the real Amazon, or is this a fake 288 00:19:15,384 --> 00:19:18,390 Amazon? So, we'll talk about that next.