1 00:00:03,410 --> 00:00:11,520 Let's now look into the generation of an alum hash and Elham hash is strictly speaking not a hash since 2 00:00:11,520 --> 00:00:15,260 it uses a DSL rhythm and not a cryptographic hash function. 3 00:00:17,060 --> 00:00:21,950 Why was Microsoft so stubbornly using weak cryptographic algorithms in the past. 4 00:00:23,100 --> 00:00:32,270 The answer is politics the export of strong cryptography used to be restricted in the US windows into 5 00:00:32,340 --> 00:00:38,080 administrators might remember a special patch that allowed them to make use of 56 keys instead of 40 6 00:00:38,080 --> 00:00:39,280 big keys. 7 00:00:41,320 --> 00:00:44,200 The patch was only released once the embargo was lifted. 8 00:00:45,300 --> 00:00:50,730 Microsoft was unable to export strong cryptographic protocols as the American government considered 9 00:00:50,730 --> 00:00:51,650 this a threat. 10 00:00:53,940 --> 00:01:02,260 As you might imagine European software producers strongly supported the ban. 11 00:01:02,400 --> 00:01:10,020 Let's return to the L-M hash assume the user's password is the string Seattle one. 12 00:01:10,200 --> 00:01:18,500 The protocol converts the string into uppercase in earlier versions of windows such as XP user passwords 13 00:01:18,530 --> 00:01:19,770 aren't case sensitive 14 00:01:22,350 --> 00:01:27,480 upper case and lower case letters can be used interchangeably since the string will be converted anyway. 15 00:01:29,480 --> 00:01:40,800 The system doesn't recognize the case of letters used in the password. 16 00:01:40,820 --> 00:01:45,620 The second drawback is that the protocol restricted allowable characters to alphanumeric only 17 00:01:51,680 --> 00:01:54,160 after a string was converted to capital letters. 18 00:01:54,170 --> 00:01:58,770 The password was divided into two parts. 19 00:01:58,970 --> 00:02:02,130 The first seven characters were the first part of the password. 20 00:02:02,360 --> 00:02:05,660 The other seven are the second part. 21 00:02:05,700 --> 00:02:11,860 The password has two ideal halves in order to make the two parts equal. 22 00:02:11,860 --> 00:02:16,850 Passwords were padded with spaces to 14 characters. 23 00:02:16,920 --> 00:02:20,290 If you use L-M they are still padded in this way. 24 00:02:21,430 --> 00:02:27,220 This has interesting implications and will come back to this later. 25 00:02:27,240 --> 00:02:31,950 One of the consequences to this solution was that an eight character password is more vulnerable than 26 00:02:31,950 --> 00:02:38,930 a password that has 7 characters the eighth character meant that a part of the password was made up 27 00:02:38,930 --> 00:02:42,920 from one character and nulls. 28 00:02:42,930 --> 00:02:44,520 This was a fixed string. 29 00:02:44,610 --> 00:02:50,710 So even from the D.S. cipher you can deduce what was there. 30 00:02:50,790 --> 00:02:55,940 The character could also hint to what was contained in the first part. 31 00:02:56,110 --> 00:03:00,610 If the character was the last digit of a birthdate you could assume that the earlier characters were 32 00:03:00,610 --> 00:03:02,030 the preceding digits. 33 00:03:04,380 --> 00:03:07,830 We already have the 2 7 character parts. 34 00:03:07,830 --> 00:03:12,460 Now each part is separately encrypted with the D.S. algorithm using a fixed key. 35 00:03:12,570 --> 00:03:21,520 A literal output of the encryptions is then joined using an ordinary concatenation. 36 00:03:21,540 --> 00:03:23,570 The result is a LAN Manager password 37 00:03:27,040 --> 00:03:30,900 as we've seen a LAN Manager password is not 14 characters long. 38 00:03:32,770 --> 00:03:38,400 It's split into two 7 character passwords since both parts of the password can be cracked separately. 39 00:03:41,970 --> 00:03:47,940 The number of operations needed to crack it is lowered again. 40 00:03:48,030 --> 00:03:56,380 It's enough to perform about 10 to 12 power operations to check all else manage your passwords for modern 41 00:03:56,380 --> 00:03:57,670 machines tend to the twelfth. 42 00:03:57,660 --> 00:04:00,120 Power is not a large number. 43 00:04:00,160 --> 00:04:02,500 A password can be cracked in a matter of seconds 44 00:04:09,100 --> 00:04:15,610 and the land manager has a protocol that employs solutions that are both simpler and less vulnerable. 45 00:04:15,610 --> 00:04:23,350 Above all it ops for a hash function instead of the D.S. because of the restrictions and the embargo 46 00:04:23,350 --> 00:04:24,340 we mentioned. 47 00:04:24,730 --> 00:04:29,590 The hash function is not very secure its message Digest version for 48 00:04:32,500 --> 00:04:37,710 is not a serious problem however as nobody will try to generate a password that will have a hash identical 49 00:04:37,710 --> 00:04:38,800 to yours. 50 00:04:41,110 --> 00:04:43,160 This attack would not make any sense. 51 00:04:45,580 --> 00:04:50,920 What's the difference between enty and LAN Manager passwords. 52 00:04:50,940 --> 00:04:55,730 First the anti passwords are case sensitive. 53 00:04:55,790 --> 00:05:02,210 They also allow you to use a password that is longer than 14 characters and implication that it's worth 54 00:05:02,210 --> 00:05:08,090 noting is that if you work on a system that uses LAN Manager for example on Windows XP with the default 55 00:05:08,090 --> 00:05:12,940 configuration is kept you should provide the 15 character password or longer 56 00:05:15,660 --> 00:05:18,880 a LAN Manager hash can be generated from this password. 57 00:05:19,090 --> 00:05:22,840 And so Windows will not generate the hash. 58 00:05:23,050 --> 00:05:31,310 You'll be a lot more secure than anybody else for any TLM the maximum password length is 127 characters. 59 00:05:32,520 --> 00:05:33,760 What does this mean. 60 00:05:36,360 --> 00:05:41,670 The simple fact that passwords aren't broken in half and letters aren't converted to uppercase means 61 00:05:41,670 --> 00:05:47,720 that an alphanumeric only password like the passwords used in LAN Manager requires tend to the 25th 62 00:05:47,730 --> 00:05:57,290 power operations to brute force this provides a lot more security. 63 00:05:57,420 --> 00:06:02,220 If you use a fourteen character password with special characters a brute force attack will take ten 64 00:06:02,220 --> 00:06:04,610 to the sixty seven power operations. 65 00:06:09,190 --> 00:06:16,600 And if you insisted on using up all the password space provided 127 characters cracking the password 66 00:06:16,610 --> 00:06:20,990 using a brute force attack would required tend to the 611 operations 67 00:06:25,250 --> 00:06:28,400 a. And then tell them passwords are deterministic. 68 00:06:29,750 --> 00:06:32,240 It's similar with Linux in Unix systems. 69 00:06:33,140 --> 00:06:37,490 Determinism means that the same hash must always be generated from the same password. 70 00:06:38,640 --> 00:06:39,600 There's no seed in it. 71 00:06:39,610 --> 00:06:41,340 That would create pseudo randomness 72 00:06:44,010 --> 00:06:48,460 when manager was used up to the release of Windows Vista. 73 00:06:48,520 --> 00:06:53,770 The protocols that replace it give us a lot more security. 74 00:06:53,850 --> 00:06:58,530 If you still use Windows XP at least select a different protocol than LAN Manager.