Explain RIPEMD-160 in brief?

RIPEMD-160 was developed in Europe as part of RIPE project in 96 by researchers involved in attacks on MD4/5. Iinitial proposal strengthen following analysis to become RIPEMD-160 somewhat similar to MD5/SHA

  1. uses 2 parallel lines of 5 rounds of 16 steps
  2. creates a 160-bit hash value
  3. slower, but probably more secure, than SHA

RIPEMD-160 Overview:

  1. pad message so its length is 448 mod 512
  2. append a 64-bit length value to message
  3. initialise 5-word (160-bit) buffer (A,B,C,D,E) to
    (67452301,efcdab89,98badcfe,10325476,c3d2e1f0)
  1. process message in 16-word (512-bit) chunks:
    • use 10 rounds of 16 bit operations on message block & buffer
    • in 2 parallel lines of 5
    • add output to input to form new buffer value
  2. output hash value is the final buffer value

RIPEMD-160 Design Criteria:

  1. use 2 parallel lines of 5 rounds for increased complexity
  2. for simplicity the 2 lines are very similar
  3. step operation very close to MD5
  4. permutation varies parts of message used
  5. circular shifts designed for best results

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Fig. Rounds of RIPEMD- 160

RIPEMD-160 Compression Function:
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RIPEMD-160 versus MD5 & SHA-1:

  1. Brute force attack harder (160 like SHA-1 vs 128 bits for MD5)
  2. not vulnerable to known attacks, like SHA-1 though stronger (compared to MD4/5)
  3. slower than MD5 (more steps)
  4. all designed as simple and compact
  5. SHA-1 optimised for big endian CPU’s vs RIPEMD-160 & MD5 optimised for little endian CPU’s

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