email or call for office visit, or call Kathy Cheek, 404 894-5696 ECE-6612 http://www.csc.gatech.edu/copeland/jac/6612/ Prof. John A. Copeland john.copeland@ece.gatech.edu 404 894-5177 fax 404 894-0035 Office: Centergy Room 5138 email or call for office visit, or call Kathy Cheek, 404 894-5696 Chapter 4b - X.509 Authentication

X.509 Authentication Service • An International Telecommunications Union (ITU) recommendation (versus “standard”) for allowing computer host or users to securely identify themselves over a network. • An X.509 certificate purchased from a “Certificate Authority” (trusted third party) allows a merchant to give you his public key in a way that your Browser can generate a session key for a transaction, and securely send that to the merchant for use during the transaction (padlock icon on screen closes to indicate transmissions are encrypted). • Once a session key is established, no one can “high jack” the session (for example, after your enter your credit card information, an intruder can not change the order and delivery address). • User only needs a Browser that can encrypt/decrypt with the appropriate algorithm, and generate session keys from truly random numbers. • Merchant’s Certificate is available to the public, only the secret key must be protected. Certificates can be cancelled if secret key is compromised.

Raw “Certificate” has user name, public key, expiration date, ... CA’s Secure Area Generate hash code of Raw Certificate Raw Cert. MIC Hash Encrypt hash code with CA’s private key to form CA’s signature Signed Cert. Signed Certificate Recipient can verify signature using CA’s public key. Certificate Authority generates the “signature” that is added to raw “Certificate” 3

4

Information Provided by Browser about a Certificate This Certificate belongs to: investing.schwab.com trading subnet a 1199 Charles Schwab & Co., Inc. Phoenix, Arizona, US This Certificate was issued by Secure Server Certification Authority RSA Data Security, Inc. US Serial Number: 6B:68:2F:3B:FD:8A:46:73:04:33:10:8A:32:1E:47:5B This Certificate is valid from Wed Nov 03, 1999 to Thu Nov 02, 2000 Certificate Fingerprint: 4B:80:C6:C5:2D:63:14:E7:6F:50:BD:16:39:3C:96:FD 5

Certificates Can Be Deleted (and Added) Are you sure that you want to delete this Site Certificate? This Certificate belongs to: endor.mcom.com Netscape Communications Corp. US This Certificate was issued by: rootca.netscape.com Information Systems Netscape Communications Corporation Serial Number: 01:77 This Certificate is valid from Thu May 15, 1997 to Tue Nov 11, 1997 Certificate Fingerprint: 06:BF:60:88:D9:E7:59:BF:3A:35:74:33:28:8E:26:F6 6

X.509 Chain of Authentication CA<<A>> = CA {A’s id and information} X<<A>> = certificate of A “signed” by X To authenticate X<<A>>, you must get the public key of X from a trusted source, such as Z - your own CA. ( Z<<X>>) Z in turn may have to get X’s certificate from a higher level CA. Ultimately there must be an “Authentication Tree” of CA’s so that a user can work up the tree (from Z) and back down to the issuer of the certificate in question, X. 7

Chain of Authentication In practice, there is no single top-level Certificate Authority (CA), only a group of CA’s that each Browser vendor deems fit to include in the installation program. X.509 Chain of Authentication 8

Certificate Authorities in Mozilla (2006) 9

Making a DES Key from a Password or Phrase password, n 7-bit ASCII characters (little endian - least significant bit first) flattened bit stream (7 x n bits) fanfold into 56 bits bitwise XOR 64-bit key Every eighth bit is a parity bit 10

Programs Available from www.csc.gatech.edu/copeland/jac/6612/tools/ hextext.c - allows you to view files in both hex and ascii formats. char_count.c - shows the number of different characters in a file, computes the character entropy. To use, you must first compile them. On a UNIX or LINUX: gcc hextext.c -o hextext (the executable file is “hextext”) ./hextext for help ./hextext filename 3000 file and max. bytes ./hextext filename 3000 | less see one screen at a time gcc char_count.c -lm -o char_count (note the “-lm” for math library) ./char_count filename If “gcc” is not available, try “cc”. “less” is better than “more” (use “^u” to back up, “space” for next page). 11

Output from ‘hextext’ 12 Maximum Lines (p_limit) value: 30 Input File is 120317-s100.raw Byte No. HEX VALUES TEXT 0 2 4 6 8 10 12 14 16 18 0 2 4 6 8 0 2 4 6 8 0: d4c3 b2a1 0200 0400 0000 0000 0000 0000 6400 0000 : ................d... 20: 0100 0000 e544 4838 1ead 0200 4e00 0000 4e00 0000 : .....DH8....N...N... 40: 0000 0000 0800 0300 0000 0000 0001 0080 1935 8da3 : .................5.. 60: 0800 4500 0040 0291 0000 3f11 16fc 1858 302f 1858 : ..E..@....?....X0/.X 80: 0142 0400 0035 002c 90c7 061a 0100 0001 0000 0000 : .B...5.,............ 100: 0000 0377 7777 0363 7363 0667 6174 6563 6803 6564 : ...www.csc.gatech.ed 120: 7500 0001 0001 e544 4838 21fd 0200 7200 0000 a400 : u......DH8!...r..... 140: 0000 0000 0000 0800 0300 0000 0000 0001 0050 0f00 : .................P.. 160: 308c 0800 4500 0096 4acf 4000 fc11 d166 1858 0142 : 0...E...J.@....f.X.B 180: 1858 302f 0035 0400 0082 7a8a 061a 8180 0001 0002 : .X0/.5....z......... 200: 0001 0001 0377 7777 0363 7363 0667 6174 6563 6803 : .....www.csc.gatech. 220: 6564 7500 0001 0001 c00c 0005 0001 0000 a1ce 0010 : edu................. Lines: 30, hextext.c by John Copeland 12/5/99 12

Output from ‘char_count’ $ ./char_count char_count.c char_count vers 000601 File is char_count.c No. Char.s to EOF = 7396, No. Lines = 183 Occurrence of Single Characters ^@- 0 | ^P- 0 | - 3488 | 0- 104 | @- 1 | P- 12 | `- 0 | p- 154 ^A- 0 | ^Q- 0 | !- 1 | 1- 77 | A- 16 | Q- 0 | a- 202 | q- 0 ^B- 0 | ^R- 0 | "- 75 | 2- 71 | B- 5 | R- 14 | b- 48 | r- 316 ^C- 0 | ^S- 0 | #- 9 | 3- 25 | C- 16 | S- 14 | c- 262 | s- 243 ^D- 0 | ^T- 0 | $- 0 | 4- 10 | D- 8 | T- 25 | d- 95 | t- 263 ^E- 0 | ^U- 0 | %- 32 | 5- 29 | E- 27 | U- 8 | e- 296 | u- 108 ^F- 0 | ^V- 0 | &- 1 | 6- 43 | F- 13 | V- 0 | f- 154 | v- 45 ^G- 0 | ^W- 0 | '- 18 | 7- 17 | G- 0 | W- 0 | g- 78 | w- 8 ^H- 0 | ^X- 0 | (- 116 | 8- 16 | H- 0 | X- 0 | h- 100 | x- 31 ^I- 18 | ^Y- 0 | )- 116 | 9- 4 | I- 27 | Y- 2 | i- 338 | y- 64 ^J- 247 | ^Z- 0 | *- 232 | :- 5 | J- 0 | Z- 0 | j- 13 | z- 4 ^K- 0 | ^[- 0 | +- 78 | ;- 193 | K- 1 | [- 104 | k- 6 | {- 24 ^L- 0 | ^\- 0 | ,- 109 | <- 35 | L- 22 | \- 29 | l- 152 | |- 4 ^M- 0 | ^]- 0 | -- 100 | =- 121 | M- 5 | ]- 102 | m- 123 | }- 24 ^N- 0 | ^^- 0 | .- 51 | >- 31 | N- 29 | ^- 4 | n- 342 | ~- 0 ^O- 0 | ^_- 0 | /- 255 | ?- 0 | O- 17 | _- 27 | o- 213 | - 0 Occurrence of Single Characters - Sorted -3488 | "- 75 | F- 13 | `- 0 | 80- 0 | A0- 0 | C0- 0 | E0- 0 13

14 Occurrence of Single Characters - Sorted -3488 | "- 75 | F- 13 | `- 0 | 80- 0 | A0- 0 | C0- 0 | E0- 0 n- 342 | 2- 71 | P- 12 | Q- 0 | 81- 0 | A1- 0 | C1- 0 | E1- 0 i- 338 | y- 64 | 4- 10 | ^B- 0 | 82- 0 | A2- 0 | C2- 0 | E2- 0 r- 316 | .- 51 | #- 9 | ^C- 0 | 83- 0 | A3- 0 | C3- 0 | E3- 0 e- 296 | b- 48 | D- 8 | $- 0 | 84- 0 | A4- 0 | C4- 0 | E4- 0 t- 263 | v- 45 | w- 8 | ^E- 0 | 85- 0 | A5- 0 | C5- 0 | E5- 0 c- 262 | 6- 43 | U- 8 | ^F- 0 | 86- 0 | A6- 0 | C6- 0 | E6- 0 /- 255 | <- 35 | k- 6 | G- 0 | 87- 0 | A7- 0 | C7- 0 | E7- 0 ^J- 247 | %- 32 | :- 5 | H- 0 | 88- 0 | A8- 0 | C8- 0 | E8- 0 s- 243 | x- 31 | B- 5 | ^A- 0 | 89- 0 | A9- 0 | C9- 0 | E9- 0 *- 232 | >- 31 | M- 5 | J- 0 | 8A- 0 | AA- 0 | CA- 0 | EA- 0 o- 213 | 5- 29 | |- 4 | ^K- 0 | 8B- 0 | AB- 0 | CB- 0 | EB- 0 a- 202 | \- 29 | ^- 4 | ^L- 0 | 8C- 0 | AC- 0 | CC- 0 | EC- 0 ;- 193 | N- 29 | z- 4 | ^M- 0 | 8D- 0 | AD- 0 | CD- 0 | ED- 0 p- 154 | _- 27 | 9- 4 | ^N- 0 | 8E- 0 | AE- 0 | CE- 0 | EE- 0 f- 154 | I- 27 | Y- 2 | ^O- 0 | 8F- 0 | AF- 0 | CF- 0 | EF- 0 l- 152 | E- 27 | @- 1 | ^P- 0 | 90- 0 | B0- 0 | D0- 0 | F0- 0 m- 123 | 3- 25 | &- 1 | q- 0 | 91- 0 | B1- 0 | D1- 0 | F1- 0 =- 121 | T- 25 | K- 1 | ^R- 0 | 92- 0 | B2- 0 | D2- 0 | F2- 0 (- 116 | {- 24 | !- 1 | ^S- 0 | 93- 0 | B3- 0 | D3- 0 | F3- 0 )- 116 | }- 24 | ^H- 0 | ^T- 0 | 94- 0 | B4- 0 | D4- 0 | F4- 0 ,- 109 | L- 22 | ^@- 0 | ^U- 0 | 95- 0 | B5- 0 | D5- 0 | F5- 0 u- 108 | '- 18 | ^V- 0 | V- 0 | 96- 0 | B6- 0 | D6- 0 | F6- 0 0- 104 | ^I- 18 | ^G- 0 | W- 0 | 97- 0 | B7- 0 | D7- 0 | F7- 0 [- 104 | 7- 17 | ^X- 0 | X- 0 | 98- 0 | B8- 0 | D8- 0 | F8- 0 ]- 102 | O- 17 | ?- 0 | ^Y- 0 | 99- 0 | B9- 0 | D9- 0 | F9- 0 h- 100 | 8- 16 | ^Z- 0 | Z- 0 | 9A- 0 | BA- 0 | DA- 0 | FA- 0 -- 100 | C- 16 | ^W- 0 | ^[- 0 | 9B- 0 | BB- 0 | DB- 0 | FB- 0 d- 95 | A- 16 | ^D- 0 | ^\- 0 | 9C- 0 | BC- 0 | DC- 0 | FC- 0 g- 78 | R- 14 | ^Q- 0 | ^]- 0 | 9D- 0 | BD- 0 | DD- 0 | FD- 0 +- 78 | S- 14 | ^^- 0 | ~- 0 | 9E- 0 | BE- 0 | DE- 0 | FE- 0 1- 77 | j- 13 | ^_- 0 | bs- 0 | 9F- 0 | BF- 0 | DF- 0 | FF- 0 Entropy is 4.5 bits/byte. Maximum character-wise compression = 56.5 % No. Char.s > 127 (not ASCII text) = 0, 0 % 14