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SHA (secure hash algorithm)

SHA (secure hash algorithm). Jen-Chang Liu, 2005 Adapted from l ecture slides by Lawrie Brown. History of SHA. SHA: secure hash algorithm Developed by National Institute of Standard and Technology (NIST) Based on the MD4 FIPS 180 in 1993

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SHA (secure hash algorithm)

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  1. SHA (secure hash algorithm) Jen-Chang Liu, 2005 Adapted from lecture slides by Lawrie Brown

  2. History of SHA • SHA: secure hash algorithm • Developed by National Institute of Standard and Technology (NIST) • Based on the MD4 • FIPS 180 in 1993 • SHA-1: revised SHA, FIPS 180-1 in 1995, also RFC 3174

  3. Secure hash algorithm (SHA) • SHA logic 512-bit block 160 160 160 160 SHA SHA SHA SHA 160-bit digest

  4. SHA round for 512-bit block 5 個 32- bit words 4 different functions: Totally 80 steps

  5. Elementary SHA operation 32 bits 32 bits 32 bits 32 bits 32 bits From 512-bit input block Circular left shift 5 bits Fixed constant

  6. SHA bitswise functions

  7. W[0-79] from input 512-bit block • W[0-79]

  8. Security of SHA • Against brute-force attack • Produce any message having a given SHA digest is on the order of 2160 • Against cryptanalysis • No known attacks • Speed • Logic operation & addition modulo 232 • Fast on 32-bit architecture • Simple to implement

  9. Improvement to SHA • Comparison of SHA-x

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