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Secure Hash Algorithm 1 (SHA-1)


Complete Definition:

The SHA-1 Algorithm that takes a message of less than 264 bits in length and produces a 160-bit message digest. The large message digest provides security against brute-force collision and inversion attacks. SHA-1 [NIS94c] is a revision to SHA that was published in 1994.


The five algorithms are denoted SHA-1, SHA-224, SHA-256, SHA-384, and SHA-512. The latter four variants are sometimes collectively referred to as SHA-2. SHA-1 produces a message digest that is 160 bits long; the number in the other four algorithms' names denote the bit length of the digest they produce.


RFCs and references

  • US Secure Hash Algorithm 1 (SHA1) - RFC 3174
  • IP Authentication using Keyed SHA1 with Interleaved Padding (IP-MAC) - RFC 2841
  • Using HMAC-SHA-256, HMAC-SHA-384, and HMAC-SHA-512 with IPsec - RFC 4868
  • US Secure Hash Algorithms (SHA and HMAC-SHA) - RFC 4634


Also See:

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Last update:
‎08-23-2017 12:50 PM
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The first line should read "... takes a message of less than 2^64 bits length...".