WEBVTT 00:00.520 --> 00:04.650 The world of computing didn't start with encryption being built into it. 00:04.810 --> 00:09.220 We could easily say that computing started in the late 1940s. 00:09.310 --> 00:16.420 So from the 1940s up until the late 1970s the idea of encrypting a mainframe computer just didn't make 00:16.420 --> 00:18.130 any sense whatsoever. 00:18.160 --> 00:23.050 Well over time we began discover you know with the Cold War and things like that that our computers 00:23.050 --> 00:28.000 we didn't want people looking into him and figuring out the data or we were moving data from one computer 00:28.000 --> 00:30.030 to another via phone lines or something. 00:30.160 --> 00:32.230 And we didn't want people to see that information. 00:32.290 --> 00:35.550 So we had to go about the process of encryption. 00:35.560 --> 00:40.640 Now when you're encrypting in the I.T. world you have to develop algorithms. 00:40.810 --> 00:44.080 Now these algorithms if you've been watching other episodes. 00:44.080 --> 00:49.690 Number one they have to be known to everybody everybody understands the algorithm and they have to have 00:49.960 --> 00:54.600 a key of different lengths and then that key has to be kept secret. 00:54.610 --> 01:01.240 So the first generation of encryption that we still see these today used what were known as a symmetric 01:01.270 --> 01:07.210 key algorithm symmetric key simply means that the person who encrypts it needs the key and then you 01:07.210 --> 01:10.810 take that key and the person who decrypts it uses the same key. 01:10.900 --> 01:13.520 It's the same key for encrypting and decrypting. 01:13.570 --> 01:17.650 Now that may seem obvious to you but if you watch other episodes you'll see there's other ways to do 01:17.650 --> 01:18.850 it anyway. 01:18.940 --> 01:23.080 So what we're going to be talking about are symmetric in Krishan algorithms. 01:23.080 --> 01:27.450 And what I want to stress is the idea of something called a block. 01:27.590 --> 01:34.900 Now a symmetric block algorithm simply means that I don't care how much data you have it takes off a 01:34.930 --> 01:35.910 chunk o data. 01:35.920 --> 01:42.010 So if it's a huge word document it takes off X amount of bytes at the beginning and encrypts that sends 01:42.010 --> 01:47.140 it off to the side then grabs another block encrypts that sends it off to the side and keeps going like 01:47.140 --> 01:48.610 that until it's all the way done. 01:48.610 --> 01:50.240 There's other ways to do it. 01:50.260 --> 01:58.150 So the first type of popular symmetric block encryption ever created was known as the data encryption 01:58.150 --> 02:05.320 standard or D.S. This was invented primarily by IBM but other people contributed as well and it developed 02:05.320 --> 02:11.380 as the first open standard used heavily by the United States government and it's still in use today. 02:11.440 --> 02:18.160 Now in other episodes we've seen Cesar Siver and vision and even a simple X or encryption. 02:18.160 --> 02:23.820 Let me show you how hairy a typical encryption is done using D.S.. 02:23.950 --> 02:28.990 The first step of D.S. encryption is to grab a 64 bit chunk of plaintext from the data stream we wish 02:28.990 --> 02:29.820 to encrypt. 02:30.070 --> 02:34.970 We perform what's known as an initial permutation a very specific stirring of the data. 02:35.110 --> 02:35.660 OK. 02:35.920 --> 02:40.450 Let's go ahead now that we've done the initial permutation and set the data aside for a moment and let's 02:40.450 --> 02:41.720 look at the key. 02:41.740 --> 02:42.520 So here's our key. 02:42.520 --> 02:45.900 Now the first thing we're going to do is drop the last eight bits off the key. 02:46.000 --> 02:49.630 We split that key into two 28 bit chunks. 02:49.630 --> 02:54.940 We then grab the first 24 bits from each half and put them together and we've created what's known as 02:54.940 --> 02:57.920 a subkey which is 48 bits. 02:57.920 --> 02:58.760 Cool right. 02:58.810 --> 03:00.210 Now let's get back to our data. 03:00.370 --> 03:02.990 We're going to perform what's known as a Feistel function. 03:02.990 --> 03:04.790 It works kind of like this. 03:04.840 --> 03:08.540 We're going to take the 64 bits and split it into two 32 bit halves. 03:08.680 --> 03:12.730 We then set one of the halves aside and we're all going to work on this one right here. 03:13.650 --> 03:20.630 So we're going to expand this half into a 48 bit chunk of data using an expansion function. 03:20.730 --> 03:26.820 We're then going to apply an X or function of this using the subkey we've already generated. 03:26.820 --> 03:34.620 Next we're going to use what are called X-boxes indeed X-boxes take in 64 bits and output for bits. 03:34.620 --> 03:38.900 There are eight different boxes and each one gives a different forbit output. 03:39.090 --> 03:45.360 So we apply the eight S-box to the data creating a 32 bit output and then we're going to do what we 03:45.360 --> 03:47.620 call a final permutation. 03:47.730 --> 03:51.720 We then put the two 32 bit chunks back together but backwards. 03:51.720 --> 03:54.070 And that completes a single Feistel function. 03:54.150 --> 03:54.910 That was fun. 03:54.990 --> 03:56.400 So let's do it again. 03:56.520 --> 04:01.150 We'll shift a few bits on the subkey we'll split the data set aside we go ahead and expand it. 04:01.150 --> 04:02.520 We are the subkey. 04:02.600 --> 04:08.370 We've applied this S-box is one more time we throw in a permutation we put the data back together get 04:08.370 --> 04:09.080 the idea. 04:09.120 --> 04:16.960 Great let's do it 14 more times Wow seems a little complicated right now. 04:16.970 --> 04:24.260 Keep in mind that what you just looked at was a very very simplified overview of Des's itself. 04:24.260 --> 04:29.150 It's actually a lot more complicated than that but that will at least get you to the idea that they 04:29.150 --> 04:35.540 cool that we can go through this wildly complicated process and using the same key we can decrypt basically 04:35.540 --> 04:38.430 reverse the process and and encrypt. 04:38.450 --> 04:41.000 We can go either direction it's absolutely fascinating. 04:41.240 --> 04:46.690 Now as wildly complicated as that was there were a couple of issues with Dell's. 04:46.760 --> 04:52.490 Number one the big problem with Des's more than anything else was its short key now 56 bits. 04:52.580 --> 04:58.520 Sounds like a wonky to you and me but in reality it's actually kind of short and it allowed it to become 04:58.550 --> 05:01.290 exposed to certain types of attacks. 05:01.310 --> 05:11.030 So by the early 1990s people were saying that we could hack Des's and now in the post 2010 2020 not 05:11.030 --> 05:14.920 that far away Des's can be hacked in certain circumstances. 05:14.960 --> 05:21.240 So even way back in the 90s they started to come up with alternatives to the alternatives you may see 05:21.470 --> 05:23.090 one of them is called Blowfish. 05:23.180 --> 05:25.700 And the other one is called Triple Des's. 05:25.700 --> 05:30.350 Now the thing I want to stress to you is that what we're talking about symmetric block encryptions there 05:30.350 --> 05:35.780 are three things we tend to talk about more anything else we talk about the key size how long the key 05:35.780 --> 05:41.420 is we talk about the number of rounds how many rounds does it go through in its encryption process. 05:41.420 --> 05:43.710 And then we also talk about the block size. 05:43.730 --> 05:48.700 So let's go through Blowfish and trippled as compared to D.S.. 05:49.160 --> 05:53.820 OK so let's go ahead and put DSN we know D.S. is a block cipher. 05:53.990 --> 05:56.580 Now it uses a 64 bit block size. 05:56.630 --> 06:00.900 It runs 16 rounds with the key size of 56 bits. 06:01.040 --> 06:07.690 That way I know we say 64 but we take at 8 bits for overhead so it's really 56 bits now. 06:07.910 --> 06:13.970 Triple Des's was also a block encryption also with a 64 bit block size. 06:14.030 --> 06:15.960 It also had 16 rounds. 06:16.070 --> 06:23.500 But basically what it did is it repeated the days process three times so you had 3:56 bit key. 06:23.510 --> 06:29.840 So in essence we had 168 that key Blowfish had a 64 bit block size. 06:29.900 --> 06:31.550 It ran 16 rounds. 06:31.550 --> 06:33.250 And the key size was variable. 06:33.250 --> 06:39.050 It could be as low as 32 bits as high as 448 bits. 06:39.050 --> 06:46.220 By the early 1990s it was obvious to the United States federal government that Des's was a very good 06:46.760 --> 06:52.030 Blowfish wasn't under their control and triple Des's was really just kind of patched together. 06:52.220 --> 06:58.610 And so the National Institute of Standards in the very late 1990s and continued into the early 2000s 06:58.940 --> 07:00.880 started a big competition. 07:01.070 --> 07:06.620 They called it a competition but it was really almost more of a like a like a conference like a big 07:06.620 --> 07:12.530 get together because we'd have people from the private sector in the public sector and from academia 07:12.560 --> 07:18.500 all submitting these new symmetric block encryptions which were going to replace all this stuff and 07:19.130 --> 07:23.420 they kind of work together so they called it the competition but there was a lot of teamwork and we 07:23.420 --> 07:28.620 started off with a few hundred submissions and they got a down to like 12 then they got it down to five. 07:28.760 --> 07:33.180 And then from the top five they basically took a vote because all the top five were very very good. 07:33.380 --> 07:39.740 And one particular algorithm called rainfall became the new what's now known as the Advanced Encryption 07:39.740 --> 07:41.540 Standard in the early 2000s. 07:41.540 --> 07:44.220 Now the Advanced Encryption Standard or alias. 07:44.240 --> 07:46.820 Yes of course it's a symmetric block encryption. 07:46.940 --> 07:52.590 But what's most important about it is that it is even though it's well over 10 years old in fact maybe 07:52.610 --> 07:57.630 getting closer to 20 These days it is in essence still unhappy of. 07:57.650 --> 07:58.950 Knock on wood on that. 07:59.060 --> 08:03.440 And it is an incredibly powerful symmetric encryption. 08:03.440 --> 08:08.140 Now I'm not even going to bother to try to show you the details of how ABS works on the inside. 08:08.210 --> 08:13.640 So let's just put that on our chart so that we know the key sizes and we know the block sizes and we 08:13.640 --> 08:15.030 know the number of rounds. 08:15.410 --> 08:22.790 So yes obviously as a block algorithm it has a block size of 128 bits. 08:22.790 --> 08:26.420 Now let's jump over to key size because you can have three different key sizes. 08:26.420 --> 08:30.940 You can have 128 192 or 256 bit keys. 08:30.930 --> 08:33.670 Basically the bigger the key the more secure you are. 08:33.830 --> 08:40.910 And now going back to round's we would have either 10 12 or 14 rounds depending on whether you had 128 08:40.910 --> 08:44.620 192 or 256 bit key sizes. 08:45.390 --> 08:53.150 Now there is one exception to the world that sounds pretty much dominated by symmetric block ciphers. 08:53.190 --> 08:58.430 There is another way to do it using what we call streaming ciphers. 08:58.440 --> 09:04.260 So instead of taking a chunk encrypting that and sending off taking a chunk encrypted it and sending 09:04.260 --> 09:08.690 it off you can do what's known as streaming in a streaming scenario. 09:08.940 --> 09:15.750 What you'll do is you'll have as each bit comes out of your through a wire or something like that so 09:15.760 --> 09:17.670 we use this in communication a lot. 09:17.670 --> 09:22.520 It literally will encrypt one bit at a time randomly making it a 1 or 0. 09:22.530 --> 09:28.680 Well it's not random it's called pseudo random but it will create it in such a way that it literally 09:28.680 --> 09:31.230 encrypts one bit at a time. 09:31.230 --> 09:38.760 So to make this easy for us there really is only one type of streaming symmetric encryption out there 09:39.030 --> 09:40.660 and that's known as RC 4. 09:40.680 --> 09:42.360 So let's throw him on the list too. 09:42.660 --> 09:48.770 So RC 4 is a streaming type of encryption. 09:48.780 --> 09:52.110 It really doesn't use block sizes it's one bit at a time. 09:52.170 --> 09:56.970 And because it only gets to see that bit once there's only one round when you're using that stream and 09:56.970 --> 10:02.310 kept encryption and the key size and this is often the case if you don't have a lot of rounds you often 10:02.310 --> 10:03.830 want to use really big keys. 10:03.870 --> 10:09.610 So the key size can be as small as 40 bits and can go up to 2048 bits. 10:09.840 --> 10:15.340 You have gone through a lot of different types of symmetric encryptions here. 10:15.390 --> 10:22.230 Now the thing about algorithms you need to understand is that at no time are you going to have to set 10:22.230 --> 10:23.850 these things up. 10:23.970 --> 10:28.860 Really we live in a world where we have these already programmed it and we're going to cover this and 10:28.860 --> 10:29.940 other episodes. 10:29.940 --> 10:33.410 But to give you one example we've probably all done wireless networks. 10:33.540 --> 10:40.080 If you set up your wireless access point to use WPA encryption you're actually using RC for Whereas 10:40.080 --> 10:44.390 if you set up for WPA too you're actually using abs encryption. 10:44.430 --> 10:51.090 So it's not so terribly important to me that you know the real complete detail difference between say 10:51.090 --> 10:57.430 Des's and triple Des's what is important is that you have a rough understanding of these types of encryptions 10:57.450 --> 11:01.420 you need to understand that they are all symmetric they all share the same key. 11:01.560 --> 11:08.100 And then also they can either be block most of them or block and with the exception of RC 4 can be streaming. 11:08.100 --> 11:11.430 So you're gonna want to take a moment to memorize that type of stuff. 11:11.610 --> 11:17.460 But the cool part is is that while we understand that we take advantage of systems that are pre-built 11:17.460 --> 11:18.000 in. 11:18.000 --> 11:23.280 So when we make choices at a higher level it's going to help determine the type of encryption that we're 11:23.280 --> 11:38.190 going to use.