1 1 00:00:00,640 --> 00:00:03,440 Layer 6, the presentation layer. 2 2 00:00:03,440 --> 00:00:04,940 Now, the presentation layer 3 3 00:00:04,940 --> 00:00:07,100 is responsible for formatting your data 4 4 00:00:07,100 --> 00:00:08,370 that's going to be exchanged 5 5 00:00:08,370 --> 00:00:11,330 and securing the data with proper encryption. 6 6 00:00:11,330 --> 00:00:13,300 So, when you think about Layer 6, 7 7 00:00:13,300 --> 00:00:15,350 there's a couple of keywords I want you to remember: 8 8 00:00:15,350 --> 00:00:17,920 data formatting and encryption. 9 9 00:00:17,920 --> 00:00:20,830 Every time we talk about data formatting or encryption, 10 10 00:00:20,830 --> 00:00:22,820 I want you to think about Layer 6, 11 11 00:00:22,820 --> 00:00:25,970 the presentation layer, inside the OSI model. 12 12 00:00:25,970 --> 00:00:28,950 Now, when I talk about data formatting, what is that? 13 13 00:00:28,950 --> 00:00:31,390 Well, data is going to be formatted by a computer 14 14 00:00:31,390 --> 00:00:33,220 so that it has compatibility between 15 15 00:00:33,220 --> 00:00:34,800 different types of devices. 16 16 00:00:34,800 --> 00:00:36,160 There are some common ones out there 17 17 00:00:36,160 --> 00:00:38,130 that you may or may not have heard of. 18 18 00:00:38,130 --> 00:00:39,910 The first one is ASCII, 19 19 00:00:39,910 --> 00:00:41,470 which stands for the American Standard 20 20 00:00:41,470 --> 00:00:43,750 for Computer Information Interchange. 21 21 00:00:43,750 --> 00:00:46,320 Now, ASCII is basically text. 22 22 00:00:46,320 --> 00:00:48,760 It's what says that the capital A is represented 23 23 00:00:48,760 --> 00:00:50,660 by the number 65. 24 24 00:00:50,660 --> 00:00:53,220 In the old days of computers, we had ASCII 25 25 00:00:53,220 --> 00:00:54,650 and it was an 8-bit code 26 26 00:00:54,650 --> 00:00:56,800 that would tell us exactly what that letter was 27 27 00:00:56,800 --> 00:00:59,790 or that symbol, and ASCII characters do that for us. 28 28 00:00:59,790 --> 00:01:02,000 For instance, ASCII character 40 29 29 00:01:02,000 --> 00:01:04,000 is the @ sign for your email. 30 30 00:01:04,000 --> 00:01:05,490 Then, we have things like GIFs 31 31 00:01:05,490 --> 00:01:08,140 which are little pictures that dance around and do motion, 32 32 00:01:08,140 --> 00:01:11,080 or we have a JPEG file which is used for photographs 33 33 00:01:11,080 --> 00:01:14,060 or a PNG which is used for images on the Internet. 34 34 00:01:14,060 --> 00:01:16,580 All of these are different types of data formats 35 35 00:01:16,580 --> 00:01:18,900 and based on that format, the computer knows 36 36 00:01:18,900 --> 00:01:20,720 how to represent it on the screen 37 37 00:01:20,720 --> 00:01:22,610 as it passes those files around. 38 38 00:01:22,610 --> 00:01:24,080 Because at the end of the day, 39 39 00:01:24,080 --> 00:01:26,460 all of these file formats really come down 40 40 00:01:26,460 --> 00:01:29,570 to a series of ones and zeros on your computer's hard drive 41 41 00:01:29,570 --> 00:01:30,720 or on your network. 42 42 00:01:30,720 --> 00:01:32,030 Now, when we talk about ASCII, 43 43 00:01:32,030 --> 00:01:35,040 it really is just a text-based language for us to use. 44 44 00:01:35,040 --> 00:01:37,050 This is going to ensure that the data is readable 45 45 00:01:37,050 --> 00:01:38,380 by the receiving system, 46 46 00:01:38,380 --> 00:01:41,600 because now we're all speaking the exact same language. 47 47 00:01:41,600 --> 00:01:44,500 Because ASCII isn't the only text-based language out there. 48 48 00:01:44,500 --> 00:01:47,180 There's Unicode and a series of other ones. 49 49 00:01:47,180 --> 00:01:49,490 But if we all use ASCII, for instance, 50 50 00:01:49,490 --> 00:01:50,450 that means we all know 51 51 00:01:50,450 --> 00:01:52,250 what the proper data structure is for it 52 52 00:01:52,250 --> 00:01:53,790 and the proper formatting. 53 53 00:01:53,790 --> 00:01:56,540 This allows us to negotiate data transfer syntax 54 54 00:01:56,540 --> 00:01:59,140 for our Layer 7 at the application layer, 55 55 00:01:59,140 --> 00:02:01,480 and we're going to talk about that in the next lesson. 56 56 00:02:01,480 --> 00:02:03,320 Now, the next piece of this layer, 57 57 00:02:03,320 --> 00:02:05,270 or Layer 6, is encryption. 58 58 00:02:05,270 --> 00:02:07,280 This is another thing that the presentation layer 59 59 00:02:07,280 --> 00:02:09,720 is going to be all about and doing for us. 60 60 00:02:09,720 --> 00:02:11,460 Encryption is used to scramble data 61 61 00:02:11,460 --> 00:02:13,770 as it goes in transit to keep it secure 62 62 00:02:13,770 --> 00:02:15,340 from any prying eyes. 63 63 00:02:15,340 --> 00:02:17,360 This is going to provide us with confidentiality 64 64 00:02:17,360 --> 00:02:21,150 of our data as it crosses our network and as it's stored. 65 65 00:02:21,150 --> 00:02:24,250 Now, some examples of this will be something like TLS 66 66 00:02:24,250 --> 00:02:26,750 which stands for Transport Layer Security. 67 67 00:02:26,750 --> 00:02:28,430 And that's what's being used right now 68 68 00:02:28,430 --> 00:02:30,480 to secure the data between your computer 69 69 00:02:30,480 --> 00:02:33,470 and a website like Facebook, or Dion Training, 70 70 00:02:33,470 --> 00:02:36,010 or Amazon, or any of the other ones out there. 71 71 00:02:36,010 --> 00:02:39,150 If you get that little padlock next to your domain name, 72 72 00:02:39,150 --> 00:02:41,870 that means you're using a TLS connection. 73 73 00:02:41,870 --> 00:02:43,440 This creates an encrypted tunnel 74 74 00:02:43,440 --> 00:02:45,770 so nobody else can see what's inside it 75 75 00:02:45,770 --> 00:02:47,530 and that way, they can't see your username, 76 76 00:02:47,530 --> 00:02:49,880 your password, and your credit card information 77 77 00:02:49,880 --> 00:02:52,010 as you pass it back and forth. 78 78 00:02:52,010 --> 00:02:55,060 Now, what are some examples of things at Layer 6? 79 79 00:02:55,060 --> 00:02:57,040 Well, things like scripting languages 80 80 00:02:57,040 --> 00:02:58,620 are going to be a Layer 6 thing, 81 81 00:02:58,620 --> 00:03:00,210 because they're formatting data. 82 82 00:03:00,210 --> 00:03:04,600 So, if we're dealing with HTML, or XML, or PHP, or JavaScript, 83 83 00:03:04,600 --> 00:03:07,340 all of those tell the text-based ASCII 84 84 00:03:07,340 --> 00:03:10,140 how it should display differently on the screen. 85 85 00:03:10,140 --> 00:03:12,410 For example, I want to make this line bold 86 86 00:03:12,410 --> 00:03:14,080 and make this other one underlined, 87 87 00:03:14,080 --> 00:03:16,250 and make this size x font. 88 88 00:03:16,250 --> 00:03:18,350 Those type of things can all be controlled 89 89 00:03:18,350 --> 00:03:21,020 using a formatting language like HTML 90 90 00:03:21,020 --> 00:03:23,360 to take the ASCII code that you typed in 91 91 00:03:23,360 --> 00:03:25,070 and translate it into something that looks better 92 92 00:03:25,070 --> 00:03:26,440 on the screen. 93 93 00:03:26,440 --> 00:03:28,630 We also have things like standard text 94 94 00:03:28,630 --> 00:03:33,230 and this would be things like ASCII, or Unicode, or EBCDIC. 95 95 00:03:33,230 --> 00:03:35,670 All of these are different ways of displaying text 96 96 00:03:35,670 --> 00:03:37,630 from those ones and zeros. 97 97 00:03:37,630 --> 00:03:39,220 We also have things like pictures, 98 98 00:03:39,220 --> 00:03:43,820 we have GIFs, and JPGs, and TIFs, and SVGs, and PNGs, 99 99 00:03:43,820 --> 00:03:45,530 and all of these type of files. 100 100 00:03:45,530 --> 00:03:47,890 They're all different ways of representing ones and zeros 101 101 00:03:47,890 --> 00:03:49,890 as different graphical formats. 102 102 00:03:49,890 --> 00:03:53,350 We also have movie files like MP4s, and MPGs, 103 103 00:03:53,350 --> 00:03:56,550 and MOV files, and all of these are going to show up 104 104 00:03:56,550 --> 00:03:58,180 as some kind of video for us, 105 105 00:03:58,180 --> 00:04:00,840 but they're all made up of these ones and zeros 106 106 00:04:00,840 --> 00:04:03,800 in a particular format and that data formatting 107 107 00:04:03,800 --> 00:04:05,930 makes it into a movie that you can watch 108 108 00:04:05,930 --> 00:04:07,750 just like this video right now. 109 109 00:04:07,750 --> 00:04:09,930 So, all of those examples I showed you so far 110 110 00:04:09,930 --> 00:04:11,420 are all about presentation, 111 111 00:04:11,420 --> 00:04:14,260 presenting text, or images, or photographs, 112 112 00:04:14,260 --> 00:04:15,780 or movies in a different way. 113 113 00:04:15,780 --> 00:04:18,690 But we also have that example of encryption algorithms. 114 114 00:04:18,690 --> 00:04:21,320 Things like TLS and SSL. 115 115 00:04:21,320 --> 00:04:23,370 Now, these are taking your ones and zeros 116 116 00:04:23,370 --> 00:04:24,730 and presenting them differently, right? 117 117 00:04:24,730 --> 00:04:26,440 Because they're scrambling them up 118 118 00:04:26,440 --> 00:04:27,730 so nobody else can see them, 119 119 00:04:27,730 --> 00:04:30,740 and it secures that data in a jumbled format. 120 120 00:04:30,740 --> 00:04:32,210 That's the idea here when you start dealing 121 121 00:04:32,210 --> 00:04:33,810 with TLS and SSL. 122 122 00:04:33,810 --> 00:04:35,480 So, it is a type of data format, 123 123 00:04:35,480 --> 00:04:37,500 but it's not just a clear presentation 124 124 00:04:37,500 --> 00:04:39,910 like we had with a movie file, or a graphic file, 125 125 00:04:39,910 --> 00:04:41,860 or an audio file, or text. 126 126 00:04:41,860 --> 00:04:43,840 Instead, when we start dealing with encryption, 127 127 00:04:43,840 --> 00:04:46,140 we're really focused on the security of the data 128 128 00:04:46,140 --> 00:04:48,723 by scrambling it up and keeping prying eyes off it.