require'digest'

Digest

This module provides a framework for message digest libraries.

You may want to look at OpenSSL::Digest as it supports more algorithms.

A cryptographic hash function is a procedure that takes data and returns a fixed bit string: the hash value, also known as digest. Hash functions are also called one-way functions, it is easy to compute a digest from a message, but it is infeasible to generate a message from a digest.

Examples

require'digest'# Compute a complete digestDigest::SHA256.digest'message'#=> "\xABS\n\x13\xE4Y..."sha256=Digest::SHA256.newsha256.digest'message'#=> "\xABS\n\x13\xE4Y..."# Other encoding formatsDigest::SHA256.hexdigest'message'#=> "ab530a13e459..."Digest::SHA256.base64digest'message'#=> "q1MKE+RZFJgr..."# Compute digest by chunksmd5=Digest::MD5.newmd5.update'message1'md5<<'message2'# << is an alias for updatemd5.hexdigest#=> "94af09c09bb9..."# Compute digest for a filesha256=Digest::SHA256.file'testfile'sha256.hexdigest

Additionally digests can be encoded in “bubble babble” format as a sequence of consonants and vowels which is more recognizable and comparable than a hexadecimal digest.

require'digest/bubblebabble'Digest::SHA256.bubblebabble'message'#=> "xopoh-fedac-fenyh-..."

See the bubble babble specification at http://web.mit.edu/kenta/www/one/bubblebabble/spec/jrtrjwzi/draft-huima-01.txt .

Digest algorithms

Different digest algorithms (or hash functions) are available:

  • MD5: See RFC 1321 The MD5 Message-Digest Algorithm

  • RIPEMD-160: As Digest::RMD160. See http://homes.esat.kuleuven.be/~bosselae/ripemd160.html.

  • SHA1: See FIPS 180 Secure Hash Standard.
  • SHA2 family: See FIPS 180 Secure Hash Standard which defines the following algorithms:
    • SHA512
    • SHA384
    • SHA256

The latest versions of the FIPS publications can be found here: http://csrc.nist.gov/publications/PubsFIPS.html.

Digest Reference

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