L02_HashMDMAC

L02_HashMDMAC

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Unformatted text preview: me meaning ? the Just 2 choices of wording at 32 different places. How to generate large no. of messages of each type to get the necessary message digest collision to pull off a B-day attack ? MD5 Message Digest Ron Rivest - 1992 RFC 1321 Input: arbitrary Output: 128-bit digest Input: 128-bit Most widely used secure hash algorithm – until recently MD5 shows significant crack in summer 2004 by a Chinese MD5 Team including: Wang Xiao Yun they had successfully constructed a pair of input message they which can produce collision, i.e. the same MD5 hash output. After several years of further effort by many other researchers, After MD5 was totally broken by Dec. 30 2008: MD5 “MD5 considered harmful TODAY”, MD5 http://www.win.tue.nl/hashclash/rogue-ca/ http://www.win.tue.nl/hashclash/rogue-ca/ The General Structure of MD5 and SHA-1 Note the possibility of attacking by “appending” at the end of the Note original message ; what should we do ? original SHA-1 Secure Hash Function SHA was designed by NIST & NSA in 1993, revised 1995 as SHA-1 ; SHA again, design criteria were not disclosed again, US standard for use with DSA signature scheme US standard is FIPS 180-1 1995, also Internet RFC3174 The algorithm is SHA, the standard is SHS The Input is processed in 512-bit blocks Produces as output a 160-bit message digest But slower than MD5 Was the generally preferred hash algorithm (than MD5) Considered to be Very Secure – Only until Feb 2005 ; Considered Only The same Chi...
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This note was uploaded on 12/05/2013 for the course IERG 4130 taught by Professor Chowsze-ming,sherman during the Fall '13 term at CUHK.

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