11.1.4 The Secure Hash Algorithm: Package Digest::SHA1

11.1.4  The Secure Hash Algorithm: Package Digest::SHA1

The Secure Hash Algorithm (SHA) was developed by the National Institute of Standards and Technology (NIST) in 1993, and was revised in 1995. It is now generally know as SHA-1. SHA is based on the MD4 algorithm.

The algorithm takes as input a message of length less than  bits and produces as output an 160-bit message digest. The input is processed in 512-bit blocks.

The SHA digest is 32 bits longer than the MD5 digest and hence is much more difficult to break using a brute-force technique, on the order of  for MD5 and  for SHA-1. MD5 has been shown to be possibly breakable using cryptanlaysis techniques. However, such vulnerabilities have not been discovered for SHA-1. SHA-1 involves more steps (80 instead of 64) and must process an 160-bit buffer compared to MD5’s 128-bit buffer. Hence, SHA-1 executes a bit more slowly than MD5 on the same machine. The Perl module Digest::SHA1 is used in the same manner as the module Digest::MD5.