WEBVTT 1 00:00:00.080 --> 00:00:02.600 Hey there, ready to dive into a world where secrets 2 00:00:02.600 --> 00:00:05.400 are scrambled and data dances through digital tunnels. 3 00:00:05.519 --> 00:00:09.759 Absolutely, today we're talking network security, the guardians of our 4 00:00:09.800 --> 00:00:10.519 digital lives. 5 00:00:10.919 --> 00:00:13.880 Okay, so picture this. It's not just about locking your 6 00:00:13.919 --> 00:00:17.160 digital doors, it's about building Fort Knox around your data. 7 00:00:17.679 --> 00:00:20.359 That's the mission we're tackling today with Network Security and 8 00:00:20.399 --> 00:00:22.719 Cryptography by doctor Sarhan M. 9 00:00:22.800 --> 00:00:25.719 Musa. You got it. This book is like a crash 10 00:00:25.760 --> 00:00:30.039 course in cybersecurity, from ancient codes to cutting edge tech. 11 00:00:30.239 --> 00:00:32.840 Right, and you know me, I love a good historical mystery. 12 00:00:33.119 --> 00:00:36.079 What really got my gears turning was the section on cipher's. 13 00:00:36.240 --> 00:00:39.240 Remember those secret codes we used as kids. Turns out 14 00:00:39.280 --> 00:00:40.920 they have a long and fascinating history. 15 00:00:41.119 --> 00:00:44.479 Absolutely, Doctor Musa actually starts with a cipher. You might 16 00:00:44.520 --> 00:00:47.880 recognize the Caesar cipher. It's incredibly simple, yet it illustrates 17 00:00:47.880 --> 00:00:51.119 a core principle of cryptography, shifting letters around to create 18 00:00:51.240 --> 00:00:52.320 a secret message. 19 00:00:52.520 --> 00:00:55.079 Oh right, it's like that secret language we invented in 20 00:00:55.159 --> 00:00:58.200 elementary school, shifting each letter a few spaces down the alphabet. 21 00:00:58.439 --> 00:01:02.359 But this book goes way beyond and simple substitution ciphers. 22 00:01:02.000 --> 00:01:06.120 Right, wavyond it dies into the complex world of modern encryption, 23 00:01:06.439 --> 00:01:10.920 which uses mind boggling mathematical formulas and algorithms to scramble 24 00:01:11.000 --> 00:01:13.680 data in a way that's incredibly difficult to crack. 25 00:01:13.760 --> 00:01:16.120 So it's like the difference between a simple padlock and 26 00:01:16.159 --> 00:01:20.000 a high tech vault with laser beams and motion sensors exactly. 27 00:01:20.519 --> 00:01:24.640 And just like building a secure vault requires understanding its blueprints, 28 00:01:24.680 --> 00:01:28.200 securing our digital lives requires understanding the blueprints of the 29 00:01:28.200 --> 00:01:30.879 Internet itself network protocols. 30 00:01:31.200 --> 00:01:34.519 Network protocols, those sound intimidating. Are we talking about the 31 00:01:34.599 --> 00:01:37.239 kind of protocols robots used to communicate with each other? 32 00:01:37.560 --> 00:01:40.560 Well, not exactly robot language, but you're on the right track. 33 00:01:41.200 --> 00:01:43.519 Think of network protocols as the rules of the road 34 00:01:43.560 --> 00:01:47.879 for data transmission, dictating how information is packaged, addressed, transmitted, 35 00:01:47.920 --> 00:01:49.480 and reassembled at its destination. 36 00:01:50.079 --> 00:01:52.799 Okay, So it's like having a set of traffic signals 37 00:01:52.840 --> 00:01:55.840 and road signs that ensure data flows smoothly and securely 38 00:01:55.879 --> 00:01:57.560 across the Internet, exactly. 39 00:01:57.879 --> 00:02:00.000 And one of the most important models for undertanding network 40 00:02:00.040 --> 00:02:04.040 protocols is the OSI model, which stands for Open Systems Interconnection. 41 00:02:04.959 --> 00:02:08.039 It's like a seven layer cake with each layer responsible 42 00:02:08.120 --> 00:02:10.960 for a specific aspect of network communication. 43 00:02:11.360 --> 00:02:14.039 Seven layers. That's a lot of layers. Can we break 44 00:02:14.080 --> 00:02:16.800 down this cake layer by layer so we're not overwhelmed 45 00:02:16.800 --> 00:02:18.159 by all the technical frosting. 46 00:02:18.319 --> 00:02:21.400 Absolutely. Let's start with the bottom layer, the foundation of 47 00:02:21.439 --> 00:02:24.520 our cake, the physical layer. It's the most basic, dealing 48 00:02:24.520 --> 00:02:27.120 with the physical transmission of data over a medium, like 49 00:02:27.159 --> 00:02:30.319 those fiber optic cables bringing you high speed Internet. 50 00:02:30.520 --> 00:02:33.479 So it's like the actual wires and cables that data 51 00:02:33.520 --> 00:02:34.840 travels through exactly. 52 00:02:34.919 --> 00:02:36.599 Now, moving up to the next layer, we have the 53 00:02:36.680 --> 00:02:39.960 data link layer. This layer focuses on ensuring that data 54 00:02:40.000 --> 00:02:44.240 is transmitted reliably between two directly connected nodes. Think of 55 00:02:44.280 --> 00:02:47.319 it as a quality control check, making sure data arrives 56 00:02:47.439 --> 00:02:48.479 without any errors. 57 00:02:48.680 --> 00:02:51.360 So it's like the postal service making sure your package 58 00:02:51.400 --> 00:02:53.120 arrives on damaged precisely. 59 00:02:53.319 --> 00:02:55.439 And now we come to the network layer, home to 60 00:02:55.439 --> 00:02:58.960 the famous IP protocol or Internet protocol, like the GPS 61 00:02:58.960 --> 00:03:01.400 of the Internet, figuring out the best route for your 62 00:03:01.479 --> 00:03:02.120 data to travel. 63 00:03:02.439 --> 00:03:06.919 Ah IP addresses those numerical labels that identify every device 64 00:03:06.960 --> 00:03:09.840 on the Internet, So this layer is responsible for directing 65 00:03:09.919 --> 00:03:11.719 data packets to the right destination. 66 00:03:12.120 --> 00:03:14.879 You got it. Now let's move up to the transport layer. 67 00:03:15.919 --> 00:03:19.479 This layer is all about reliable and orderly data delivery. 68 00:03:20.520 --> 00:03:23.840 Imagine sending a large email. This layer make sure it 69 00:03:23.919 --> 00:03:26.479 arrives in the correct order without any missing pieces. 70 00:03:26.560 --> 00:03:28.520 So it's like putting all the puzzle pieces back together 71 00:03:28.560 --> 00:03:29.840 in the right order exactly. 72 00:03:30.240 --> 00:03:33.120 Now we come to the session layer. This one manages 73 00:03:33.159 --> 00:03:36.400 the communication sessions between applications, kind of like setting up 74 00:03:36.400 --> 00:03:37.280 and ending a phone call. 75 00:03:37.639 --> 00:03:42.240 Interesting, so it's responsible for establishing and terminating those connections precisely. 76 00:03:42.560 --> 00:03:46.000 They're moving onto the presentation layer. This layer handles how 77 00:03:46.080 --> 00:03:50.199 data is formatted, presented, and yes, even encrypted. It ensures 78 00:03:50.240 --> 00:03:52.879 that what one application sends can be understood by another, 79 00:03:53.159 --> 00:03:54.960 even if they speak different digital languages. 80 00:03:55.000 --> 00:03:57.840 So it's like a universal translator for data exactly. 81 00:03:58.080 --> 00:04:01.360 And finally we reach the top layer, the application layer. 82 00:04:01.800 --> 00:04:04.919 This is where users and applications interact directly. Think email, 83 00:04:04.960 --> 00:04:07.039 web browsing, and all those apps you use every day. 84 00:04:07.280 --> 00:04:09.840 Wow, so every time I check my email, I'm interacting 85 00:04:09.879 --> 00:04:13.479 with all seven layers of the OSI model. It's amazing 86 00:04:13.520 --> 00:04:14.840 how much goes on behind the scenes. 87 00:04:14.919 --> 00:04:16.759 It is, and each of these layers has its own 88 00:04:16.759 --> 00:04:19.600 security considerations. Which is where things get really interesting. 89 00:04:19.879 --> 00:04:22.959 Okay, so we've got our seven layer cake of network protocols, 90 00:04:23.399 --> 00:04:25.839 but how do we actually protect this cake from being 91 00:04:25.839 --> 00:04:27.199 devoured by cyber threats? 92 00:04:27.319 --> 00:04:30.839 That's where doctor Moosa's discussion of firewalls comes in. They're 93 00:04:30.920 --> 00:04:33.879 like the security guards of our networks, positioned to control 94 00:04:33.920 --> 00:04:36.360 the flow of incoming and outgoing traffic. 95 00:04:36.480 --> 00:04:39.319 So they act like a digital bouncer checking IDs at 96 00:04:39.360 --> 00:04:41.160 the door of our network exactly. 97 00:04:41.439 --> 00:04:43.399 Think of it like this. You have your trusted internal 98 00:04:43.439 --> 00:04:45.879 network like your home Wi Fi, and then there's the 99 00:04:45.959 --> 00:04:49.839 vast outside world of the Internet. A firewall acts as 100 00:04:49.839 --> 00:04:53.000 a barrier between the two, allowing only authorized traffic to 101 00:04:53.040 --> 00:04:53.600 pass through. 102 00:04:53.800 --> 00:04:56.000 So how do these firewalls actually work. Do they have 103 00:04:56.040 --> 00:04:58.680 a list of good and bad IP addresses? 104 00:04:58.839 --> 00:05:01.959 It's a bit more sophisticated than that. One common type 105 00:05:02.000 --> 00:05:05.879 is the packet filtering firewall. It examines each incoming and 106 00:05:05.959 --> 00:05:09.120 outgoing data packet. Think of it like a digital envelope 107 00:05:09.560 --> 00:05:13.199 and makes decisions based on criteria like the source and 108 00:05:13.240 --> 00:05:16.720 destination IP addresses, port numbers, and even the type of 109 00:05:16.759 --> 00:05:17.800 protocol being used. 110 00:05:18.079 --> 00:05:20.959 So it's like a customs agent inspecting each package that 111 00:05:21.120 --> 00:05:22.360 enters or leaves a country. 112 00:05:22.720 --> 00:05:24.879 That's a great way to put it. But while these 113 00:05:24.879 --> 00:05:29.240 packet filtering firewalls are great for basic protection, some sneaky 114 00:05:29.279 --> 00:05:31.959 cyber attackers disguise their malicious traffic as. 115 00:05:31.879 --> 00:05:35.680 Harmless, so we need even smarter firewalls for those tricksters. 116 00:05:35.879 --> 00:05:40.120 Exactly. That's where stateful inspection firewalls come in. They're like 117 00:05:40.120 --> 00:05:43.600 the detectives of the firewall world. Imagine this. Instead of 118 00:05:43.639 --> 00:05:46.519 just looking at each data packet and isolation, they keep 119 00:05:46.560 --> 00:05:49.360 track of the entire conversation between your computer and the 120 00:05:49.360 --> 00:05:50.120 outside world. 121 00:05:50.160 --> 00:05:52.800 So they're like those security guards who remember your face 122 00:05:52.800 --> 00:05:54.600 and what you're allowed to do in the building, making 123 00:05:54.600 --> 00:05:56.480 it harder for someone to slip in unnoticed. 124 00:05:56.759 --> 00:05:59.600 You got it. They look for patterns and anomalies that 125 00:05:59.639 --> 00:06:02.639 suggest something fishy is going on, even if the individual 126 00:06:02.720 --> 00:06:04.680 data packets look innocent on the surface. 127 00:06:04.920 --> 00:06:08.560 That's pretty impressive. But even with these super smart firewalls, 128 00:06:08.680 --> 00:06:11.360 I bet some cyber threats still manage to sneak through 129 00:06:11.399 --> 00:06:12.160 the cracks, right. 130 00:06:12.480 --> 00:06:17.040 Unfortunately, you're right. No security system is fool proof, which 131 00:06:17.120 --> 00:06:21.439 is why we have another layer of protection, intrusion detection 132 00:06:21.519 --> 00:06:23.519 systems or IDs for short. 133 00:06:23.399 --> 00:06:25.439 Oh ideas, I always thought those were just for those 134 00:06:25.519 --> 00:06:28.040 high security government facilities. What exactly do they do? 135 00:06:28.160 --> 00:06:30.800 Think of IDs as the alarm system for your network. 136 00:06:31.639 --> 00:06:34.920 They constantly monitor for any suspicious activity that might have 137 00:06:34.959 --> 00:06:38.680 slipped past the firewall, acting like vigilant guards, even when 138 00:06:38.720 --> 00:06:39.560 the doors are locked. 139 00:06:39.680 --> 00:06:42.279 So even if a cyber threat gets past the bouncer, 140 00:06:42.959 --> 00:06:45.439 the alarm bells start ringing thanks to the IDs. 141 00:06:45.839 --> 00:06:50.040 Exactly, they analyze network traffic for any signs of malicious intent, 142 00:06:50.199 --> 00:06:52.600 like someone trying to pry open a window or sneak 143 00:06:52.639 --> 00:06:53.439 in through the back door. 144 00:06:53.600 --> 00:06:56.319 That's reassuring. So they're like the security cameras and motion 145 00:06:56.480 --> 00:06:58.160 sensors that keep an eye out twenty four. 146 00:06:58.000 --> 00:07:02.279 To seven exactly, and when they spot something suspicious, they 147 00:07:02.319 --> 00:07:05.360 can raise the alarm, log the event, and even take 148 00:07:05.439 --> 00:07:06.639 action to block the threat. 149 00:07:06.959 --> 00:07:09.879 It sounds like they're the real heroes of network security, 150 00:07:09.959 --> 00:07:10.920 always on high alert. 151 00:07:11.160 --> 00:07:14.680 They play a crucial role in minimizing damage and preventing 152 00:07:14.680 --> 00:07:17.959 those close calls from turning into full blown security breaches. 153 00:07:18.199 --> 00:07:21.560 So we've got our firewalls acting as gatekeepers and intrusion 154 00:07:21.600 --> 00:07:25.759 detection systems as are vigilant watchdogs. But what about securing 155 00:07:25.839 --> 00:07:28.800 the data itself. That's where encryption comes in, right. 156 00:07:28.680 --> 00:07:32.800 Absolutely, and that's where things get really interesting. We're diving 157 00:07:32.839 --> 00:07:36.000 headfirst into the world of cryptography where secrets are scrambled 158 00:07:36.160 --> 00:07:38.319 and codes rule our cryptography. 159 00:07:38.360 --> 00:07:39.959 It sounds like something out of a spy movie, all 160 00:07:40.040 --> 00:07:40.759 cloak and dagger. 161 00:07:40.959 --> 00:07:44.639 It kind of is. Remember those ciphers we talked about earlier, 162 00:07:44.759 --> 00:07:48.079 That's just the tip of the iceberg. Cryptography encompasses a 163 00:07:48.120 --> 00:07:51.920 wide range of techniques used to protect information from unauthorized access, 164 00:07:52.240 --> 00:07:56.240 from simple substitution sofers to incredibly complex algorithms that would 165 00:07:56.240 --> 00:07:56.920 make your head spin. 166 00:07:57.240 --> 00:07:59.399 Well, I'm always up for a challenge. Give us the 167 00:07:59.439 --> 00:08:03.120 insights goop on how this cryptographic magic works. What are 168 00:08:03.160 --> 00:08:06.199 the key players in this world of secret codes and 169 00:08:06.240 --> 00:08:07.120 digital locks. 170 00:08:07.560 --> 00:08:10.639 At the heart of it all are encryption algorithms, which 171 00:08:10.680 --> 00:08:15.199 are like mathematical recipes for scrambling data into an unreadable mess. 172 00:08:16.079 --> 00:08:19.519 But here's the catch. To unscramble it, you need a 173 00:08:19.560 --> 00:08:21.279 secret ingredient, a key. 174 00:08:21.560 --> 00:08:23.439 So it's like having a lock that only opens with 175 00:08:23.480 --> 00:08:25.000 a specific key exactly. 176 00:08:25.439 --> 00:08:27.759 And that's the beauty of cryptography. Even if someone gets 177 00:08:27.759 --> 00:08:30.160 their hands on the encrypted data, it's just a jumble 178 00:08:30.160 --> 00:08:31.639 of gibberish without the right key. 179 00:08:31.959 --> 00:08:34.000 Okay, that makes sense. So let's say I want to 180 00:08:34.039 --> 00:08:36.799 send you a super secret message online. How do we 181 00:08:36.919 --> 00:08:40.039 use this encryption magic to keep it safe from prying eyes. 182 00:08:40.240 --> 00:08:42.200 Well, there are a few ways to approach this, but 183 00:08:42.279 --> 00:08:45.080 one of the most fundamental distinctions in cryptography is between 184 00:08:45.080 --> 00:08:48.600 symmetric key encryption and public key encryption. Think of it 185 00:08:48.679 --> 00:08:50.960 like this. Symmetric key encryption, it's like having a single 186 00:08:51.039 --> 00:08:54.039 key that can both lock and unlock a box. You 187 00:08:54.080 --> 00:08:55.759 and I would both need a copy of this key 188 00:08:55.799 --> 00:08:57.279 to exchange secret messages. 189 00:08:57.480 --> 00:08:59.679 Okay, so it's like sharing a secret code that only 190 00:08:59.720 --> 00:09:03.000 we know. But what if it's difficult to exchange keys 191 00:09:03.039 --> 00:09:05.720 securely in the first place. What if we're miles apart 192 00:09:05.840 --> 00:09:07.960 or someone is eavesdropping on our conversation. 193 00:09:08.240 --> 00:09:10.960 That's where public key encryption comes in. It's a real 194 00:09:11.039 --> 00:09:14.039 game changer. It's like having a special mailbox with two locks. 195 00:09:14.440 --> 00:09:17.320 One lock is public. Anyone can drop a message through 196 00:09:17.320 --> 00:09:20.559 the slot, but only you, with your unique private key 197 00:09:20.600 --> 00:09:23.240 can unlock the mailbox and retrieve the messages. 198 00:09:23.440 --> 00:09:25.799 That's brilliant. So I could send you a secret message 199 00:09:25.799 --> 00:09:28.080 by locking it with your public key and only you, 200 00:09:28.120 --> 00:09:30.279 with your private key could unlock it, no more worrying 201 00:09:30.320 --> 00:09:32.559 about someone intercepting the key itself. 202 00:09:32.360 --> 00:09:35.519 Exactly, And that's the elegance of public key encryption. It 203 00:09:35.600 --> 00:09:39.000 solves the key distribution problem, allowing us to communicate securely 204 00:09:39.080 --> 00:09:40.480 even if we've never met before. 205 00:09:40.679 --> 00:09:42.960 That's incredible. It seems like public key encryption is the 206 00:09:43.039 --> 00:09:45.399 ultimate solution for secure online communication. 207 00:09:45.919 --> 00:09:49.240 It's certainly a powerful tool in the cryptographic arsenal. But 208 00:09:49.360 --> 00:09:51.960 before we dive into the specifics of how public key 209 00:09:52.000 --> 00:09:55.600 systems like RSA and ECC actually work, let's take a 210 00:09:55.600 --> 00:09:57.799 closer look at the world of symmetric key encryption. 211 00:09:58.120 --> 00:10:00.720 All right, back to the world of shared secrets. Can 212 00:10:00.759 --> 00:10:03.600 you give us an example of a widely used symmetric 213 00:10:03.679 --> 00:10:05.519 key encryption algorithm? 214 00:10:05.679 --> 00:10:09.480 Absolutely. One such algorithm that's played a significant role in 215 00:10:09.519 --> 00:10:14.279 the history of cryptography is DES or, the data encryption 216 00:10:14.399 --> 00:10:15.840 standard DES. 217 00:10:15.960 --> 00:10:18.159 That name rings a bell. It sounds familiar. 218 00:10:18.320 --> 00:10:21.759 You've probably encountered it more than you realize. DES was 219 00:10:21.759 --> 00:10:25.600 once the gold standard for securing everything from financial transactions 220 00:10:25.639 --> 00:10:27.399 to government communications. 221 00:10:27.639 --> 00:10:29.399 Wow, so it was a big deal in the world 222 00:10:29.440 --> 00:10:31.720 of encryption. What made DES so special? 223 00:10:31.879 --> 00:10:35.080 Well, DS was groundbreaking for its time because it introduced 224 00:10:35.080 --> 00:10:39.519 a revolutionary concept in cryptography, the feistal network. It's a 225 00:10:39.559 --> 00:10:41.840 specific structure for designing block ciphers. 226 00:10:42.200 --> 00:10:44.519 Block cipher's. We've been throwing around a lot of terms today. 227 00:10:44.559 --> 00:10:46.399 Can you refresh my memory on what those are again? 228 00:10:46.480 --> 00:10:49.279 You bet? Remember how I mentioned that encryption algorithms are 229 00:10:49.320 --> 00:10:52.440 like recipes for scrambling data. Will block ciphers take this 230 00:10:52.559 --> 00:10:54.960 recipe and apply it to fix sized blocks of data, 231 00:10:55.399 --> 00:10:58.960 like chopping up a secret message into smaller, more manageable chunks. 232 00:10:59.000 --> 00:11:01.440 Okay, that makes sense, So how does this fistyle network 233 00:11:01.480 --> 00:11:02.399 fit into the picture. 234 00:11:02.679 --> 00:11:06.399 The feistyle network is like a well choreographed dance for 235 00:11:06.559 --> 00:11:11.080 data encryption. It takes those fixed sized blocks of data 236 00:11:11.159 --> 00:11:13.639 and puts them through a series of steps, kind of 237 00:11:13.679 --> 00:11:17.919 like a factory assembly line, where each step involves substituting 238 00:11:17.960 --> 00:11:20.559 and rearranging the bits within the block based on a 239 00:11:20.600 --> 00:11:21.120 secret key. 240 00:11:21.320 --> 00:11:23.799 So it's like putting those chunks of data through a 241 00:11:24.120 --> 00:11:29.039 cryptographic blender, scrambling them up based on a secret recipe exactly. 242 00:11:29.480 --> 00:11:31.600 And the beauty of the fystyle network is that it 243 00:11:31.639 --> 00:11:35.039 can be repeated multiple times, each time with a different 244 00:11:35.080 --> 00:11:39.200 subkey derived from the original key, making the encryption incredibly strong. 245 00:11:39.399 --> 00:11:40.960 So the more times you put the data through this 246 00:11:41.039 --> 00:11:43.600 cryptographic blender, the more scrambled it becomes. 247 00:11:43.639 --> 00:11:46.759 Precisely, each repetition is called a round, and the more 248 00:11:46.840 --> 00:11:49.480 rounds a block cipher has, the harder it is to crack. 249 00:11:49.840 --> 00:11:52.039 That's fascinating. It seems like the FISTLE network was a 250 00:11:52.039 --> 00:11:53.960 real game changer in the world of encryption. 251 00:11:54.080 --> 00:11:57.080 It certainly was. It revolutionized the design of block ciphers 252 00:11:57.399 --> 00:12:00.519 and became a fundamental building block for any encryption algorithms 253 00:12:00.519 --> 00:12:01.960 that followed, including DES. 254 00:12:02.399 --> 00:12:06.200 So DES uses this feistal network to scramble data in 255 00:12:06.279 --> 00:12:10.360 multiple rounds, making it really secure for its time. But 256 00:12:10.799 --> 00:12:12.759 how exactly does it work in practice? 257 00:12:13.200 --> 00:12:16.519 Imagine this DES takes a sixty four bit block of 258 00:12:16.559 --> 00:12:19.440 plaintext that's like a small chunk of your secret message, 259 00:12:19.799 --> 00:12:21.320 and divides it into two halves. 260 00:12:21.559 --> 00:12:23.960 Okay, so we've split our secret message in two. What 261 00:12:24.080 --> 00:12:24.840 happens next? 262 00:12:25.279 --> 00:12:29.240 Now the right half goes through a series of transformations, mixing, shifting, 263 00:12:29.279 --> 00:12:32.080 and combining the data with a subkey for that particular round. 264 00:12:32.559 --> 00:12:34.799 It's like putting that half of the message through a 265 00:12:34.840 --> 00:12:36.399 high security obstacle. 266 00:12:36.000 --> 00:12:38.600 Course, an obstacle course for data. I love it. So 267 00:12:38.679 --> 00:12:41.240 it's not just about shifting letters around like in the 268 00:12:41.279 --> 00:12:44.039 Caesar cipher. It's about manipulating the bits themselves in a 269 00:12:44.080 --> 00:12:45.360 complex way exactly. 270 00:12:45.399 --> 00:12:48.879 And here's the crucial part. The output of this obstacle course, 271 00:12:48.879 --> 00:12:51.799 as transformed right half, is then combined with the left 272 00:12:51.799 --> 00:12:55.360 half of the data using an xor operation xor. 273 00:12:55.759 --> 00:12:57.720 You're speaking my language now, I remember that from my 274 00:12:57.759 --> 00:13:00.440 computer science classes. But how does xo oring it with 275 00:13:00.440 --> 00:13:02.159 the other half make it more secure? 276 00:13:02.480 --> 00:13:06.919 Xorr or exclusive or is a bit wise operation that's reversible, 277 00:13:07.200 --> 00:13:09.440 meaning you can get back the original data if you 278 00:13:09.600 --> 00:13:12.480 x or it again with the same value. But here's 279 00:13:12.519 --> 00:13:16.120 the key. By exoring the transformed right half with the 280 00:13:16.200 --> 00:13:19.879 left half, we're essentially creating a dependency between the two halves. 281 00:13:20.120 --> 00:13:22.440 So it's like linking the two halves together in a 282 00:13:22.440 --> 00:13:24.759 way that makes them inseparable precisely. 283 00:13:25.200 --> 00:13:28.559 And this process of splitting, transforming, combining, and swapping the 284 00:13:28.559 --> 00:13:32.240 halves is repeated over sixteen rounds in des each with 285 00:13:32.279 --> 00:13:33.080 a different subkey. 286 00:13:33.279 --> 00:13:36.519 Sixteen rounds. That sounds incredibly thorough. It's like putting the 287 00:13:36.600 --> 00:13:39.399 data through a security gauntlet, making it virtually impossible to 288 00:13:39.480 --> 00:13:40.600 unscramble without the key. 289 00:13:40.759 --> 00:13:43.360 That's the idea. And because of this intricate structure and 290 00:13:43.399 --> 00:13:47.600 the multiple rounds, DIES was incredibly resilient for its time. However, 291 00:13:47.759 --> 00:13:50.799 as computers became more powerful, the fifty six bit key 292 00:13:50.879 --> 00:13:53.799 used in DES became vulnerable to brute force attacks. 293 00:13:54.120 --> 00:13:57.200 So even with this amazing feistal network and all those rounds, 294 00:13:57.279 --> 00:13:59.399 the strength of DEES ultimately came down to the length 295 00:13:59.399 --> 00:14:00.320 of the key itself. 296 00:14:00.639 --> 00:14:04.960 You got it. A longer key means more possible combinations, 297 00:14:05.279 --> 00:14:09.120 making it exponentially harder to crack through brute force. Think 298 00:14:09.159 --> 00:14:12.120 of it like trying to guess a combination lock. The 299 00:14:12.120 --> 00:14:14.679 more digits the lock has, the harder it is to 300 00:14:14.679 --> 00:14:15.840 guess the correct combination. 301 00:14:16.039 --> 00:14:18.679 That makes perfect sense. So how did the world of 302 00:14:18.679 --> 00:14:22.039 cryptography adapt to the need for stronger encryption? Did they 303 00:14:22.080 --> 00:14:23.879 just invent a whole new algorithm. 304 00:14:24.080 --> 00:14:26.679 They did develop new algorithms, but one approach was to 305 00:14:26.679 --> 00:14:31.000 build upon the strengths of DS while addressing its keylength limitation. 306 00:14:31.559 --> 00:14:34.519 That's where triple DES or three DES came into play. 307 00:14:34.600 --> 00:14:37.360 Triple DS, it sounds like they just tripled the security. 308 00:14:37.440 --> 00:14:38.159 How does it work? 309 00:14:38.240 --> 00:14:41.159 It's exactly what it sounds like Triple DES essentially applies 310 00:14:41.200 --> 00:14:43.720 to the DS algorithm three times in a row, each 311 00:14:43.799 --> 00:14:45.080 time with a different key. 312 00:14:45.240 --> 00:14:48.279 So it's like putting your secret message in three different boxes, 313 00:14:48.519 --> 00:14:50.039 each with its own unique key. 314 00:14:50.200 --> 00:14:53.320 Exactly. This tripled the effective key length, making it much 315 00:14:53.360 --> 00:14:56.960 more resistant to brute force attacks. It's like adding two 316 00:14:56.960 --> 00:14:59.720 extra locks to your front door, deterring even the most 317 00:14:59.679 --> 00:15:00.879 DES intruders. 318 00:15:01.240 --> 00:15:04.320 That makes perfect sense. Triple DES sounds like a simple 319 00:15:04.399 --> 00:15:08.799 but effective way to bolster security. But as technology continue 320 00:15:08.840 --> 00:15:13.120 to evolve, I'm sure even stronger encryption algorithms emerged. What 321 00:15:13.159 --> 00:15:14.799 are some of the heavy hitters in the world of 322 00:15:14.840 --> 00:15:16.840 symmetric key encryption today? 323 00:15:17.159 --> 00:15:20.559 You, cryptography is a constantly evolving field. One of the 324 00:15:20.600 --> 00:15:24.840 successors to DES that you've likely encountered is AES, or 325 00:15:24.879 --> 00:15:26.840 the Advanced Encryption Standard AES. 326 00:15:26.960 --> 00:15:28.879 That rings a bell. It seems like I see that 327 00:15:28.879 --> 00:15:30.159 acronym everywhere these days. 328 00:15:30.240 --> 00:15:34.039 It's the reigning champion of symmetric key encryption, widely adopted 329 00:15:34.080 --> 00:15:37.399 as the standard for securing everything from online banking to 330 00:15:37.600 --> 00:15:39.679 virtual private networks VPNs. 331 00:15:39.759 --> 00:15:42.279 Wow, so it's the fort Knox of encryption algorithms. What 332 00:15:42.320 --> 00:15:43.240 makes AES so. 333 00:15:43.240 --> 00:15:47.559 Specials is a block cipher, but it operates on larger 334 00:15:47.559 --> 00:15:50.120 block sizes and supports a variety of key length, making 335 00:15:50.159 --> 00:15:52.080 it more robust against brute force attacks. 336 00:15:52.159 --> 00:15:55.080 Okay, so larger blocks and longer keys. It's like upgrading 337 00:15:55.080 --> 00:15:57.279 from a standard sized vault to one that's twice as 338 00:15:57.279 --> 00:15:58.960 big with a more complex lock. 339 00:15:59.080 --> 00:16:02.480 Exactly and beyond its strength, AES is also known for 340 00:16:02.519 --> 00:16:06.320 its efficiency, making it suitable for a wide range of applications, 341 00:16:06.360 --> 00:16:10.759 from securing data on your smartphone to protecting sensitive government communications. 342 00:16:11.120 --> 00:16:15.080 As sounds like the gold standard of encryption algorithms, but 343 00:16:15.200 --> 00:16:18.759 we've only scratched the surface of cryptography. Earlier. You mentioned 344 00:16:18.759 --> 00:16:22.799 public key encryption and how it revolutionized secure communications. Can 345 00:16:22.840 --> 00:16:26.039 you tell us more about how those systems actually work absolutely. 346 00:16:26.240 --> 00:16:30.519 Public key encryption, also known as asymmetric cryptography, relies on 347 00:16:30.559 --> 00:16:34.600 a fascinating concept, key pairs. Each user has two keys, 348 00:16:35.080 --> 00:16:37.279 a public key which they can freely share with anyone, 349 00:16:37.600 --> 00:16:39.679 and a private key which they must keep secret. 350 00:16:40.080 --> 00:16:42.799 So it's like having two keys for a special mailbox, 351 00:16:43.120 --> 00:16:45.320 one key that anyone can use to drop a message in, 352 00:16:45.360 --> 00:16:47.960 and another key private that only you have to open 353 00:16:47.960 --> 00:16:49.320 the mailbox and read the messages. 354 00:16:49.360 --> 00:16:51.879 That's a great analogy. The magic of public key encryption 355 00:16:52.000 --> 00:16:54.279 is that anything encrypted with the public key can only 356 00:16:54.320 --> 00:16:57.279 be decrypted with a corresponding private key, and vice versa. 357 00:16:57.399 --> 00:16:59.759 So if I wanted to send you a secret message, 358 00:17:00.120 --> 00:17:02.919 I could encrypt it with your public key, and only you, 359 00:17:03.000 --> 00:17:05.720 with your private key, could decrypt it. No need to 360 00:17:05.720 --> 00:17:09.000 worry about someone intercepting the key itself, because only you 361 00:17:09.079 --> 00:17:11.079 have that private key, exactly. 362 00:17:11.599 --> 00:17:15.079 And that's how public key encryption solves the key distribution 363 00:17:15.240 --> 00:17:19.039 problem that plagued symmetric key systems. It's like having a 364 00:17:19.079 --> 00:17:22.319 secure channel for exchanging secrets without ever having to meet 365 00:17:22.319 --> 00:17:24.240 in person to exchange a key beforehand. 366 00:17:24.319 --> 00:17:27.599 That's incredibly clever. But how are these key pairs generated 367 00:17:27.640 --> 00:17:29.799 in the first place. It sounds like some next level 368 00:17:29.880 --> 00:17:31.839 mathematical wizardry is involved. 369 00:17:31.960 --> 00:17:34.640 You're right, it does involve a bit of math. One 370 00:17:34.640 --> 00:17:38.839 of the most widely used public key cryptosystems, RSA, relies 371 00:17:38.880 --> 00:17:41.359 on the difficulty of factoring large numbers. 372 00:17:41.359 --> 00:17:44.640 Factoring as in finding the prime numbers that multiply together 373 00:17:44.720 --> 00:17:46.400 to create a larger number exactly. 374 00:17:46.640 --> 00:17:48.440 Remember how in school we learned to break down a 375 00:17:48.519 --> 00:17:51.839 number like twelve into its prime factors two, two, and three. Yeah, 376 00:17:52.119 --> 00:17:55.160 YSA takes this concept to the extreme, using incredibly large 377 00:17:55.200 --> 00:17:58.599 numbers that would take classical computers billions of years to factor. 378 00:17:58.759 --> 00:18:01.559 So it's like creating a lot where the combination is 379 00:18:01.599 --> 00:18:05.119 the product of two massive prime numbers. Even if you 380 00:18:05.200 --> 00:18:08.440 know the product, figuring out those two original prime numbers 381 00:18:08.519 --> 00:18:10.079 is incredibly. 382 00:18:09.400 --> 00:18:14.200 Difficult, precisely, and that difficulty is the foundation of RSA's security. 383 00:18:14.839 --> 00:18:17.160 Let's say you want to generate an RSA key pair. 384 00:18:17.759 --> 00:18:21.200 You'd start by randomly selecting two large prime numbers. These 385 00:18:21.200 --> 00:18:24.480 are kept secret. Then you multiply those prime numbers together 386 00:18:24.880 --> 00:18:28.480 to get a much larger number. This larger number is 387 00:18:28.519 --> 00:18:30.440 part of both your public and private key. 388 00:18:31.400 --> 00:18:33.880 So it's like mixing two secret ingredients to create a 389 00:18:33.960 --> 00:18:37.359 unique flavor that's nearly impossible to replicate without knowing the 390 00:18:37.400 --> 00:18:38.319 original ingredients. 391 00:18:38.359 --> 00:18:40.359 That's a great way to put it. Now, without having 392 00:18:40.359 --> 00:18:42.359 in the mathematical details, just know that the rest of 393 00:18:42.400 --> 00:18:45.599 the key generation process involves some clever calculations using these 394 00:18:45.640 --> 00:18:48.359 prime numbers and something called modular arithmetic. 395 00:18:48.480 --> 00:18:51.880 Modular arithmetic that's ringing a faint bell from my math classes, 396 00:18:52.079 --> 00:18:53.400 something to do with remainders, right. 397 00:18:53.319 --> 00:18:55.200 Hey, you got it. It's a bit like clock arithmetic. 398 00:18:55.279 --> 00:18:57.799 Think of a twelve hour clock. If it's ten o'clock 399 00:18:57.839 --> 00:19:00.000 and you add five hours, you don't get fifteen o'clock, 400 00:19:00.039 --> 00:19:00.920 you get three o'clock. 401 00:19:01.160 --> 00:19:03.839