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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
Input: arbitrary Output: 128-bit digest
Most widely used secure hash algorithm – until recently
MD5 shows significant crack in summer 2004 by a Chinese
Team including: Wang Xiao Yun they had successfully constructed a pair of input message
which can produce collision, i.e. the same MD5 hash output.
After several years of further effort by many other researchers,
MD5 was totally broken by Dec. 30 2008:
MD5 “MD5 considered harmful TODAY”,
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
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 ;
again, design criteria were not disclosed
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
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 ;
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.
- Fall '13