In Files

  • digest/bubblebabble/bubblebabble.c
  • digest/digest.c
  • digest/lib/digest.rb
  • digest/md5/md5init.c
  • digest/rmd160/rmd160init.c
  • digest/sha1/sha1init.c
  • digest/sha2/lib/sha2.rb


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.


require 'digest'

# Compute a complete digest
Digest::SHA256.digest 'message'       #=> "\xABS\n\x13\xE4Y..."

sha256 =
sha256.digest 'message'               #=> "\xABS\n\x13\xE4Y..."

# Other encoding formats
Digest::SHA256.hexdigest 'message'    #=> "ab530a13e459..."
Digest::SHA256.base64digest 'message' #=> "q1MKE+RZFJgr..."

# Compute digest by chunks
md5 =
md5.update 'message1'
md5 << 'message2'                     # << is an alias for update

md5.hexdigest                         #=> "94af09c09bb9..."

# Compute digest for a file
sha256 = Digest::SHA256.file 'testfile'

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

Digest algorithms

Different digest algorithms (or hash functions) are available:


See RFC 1321 The MD5 Message-Digest Algorithm


As Digest::RMD160. See


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:



A mutex for Digest().

Public Class Methods

bubblebabble(string) → bubblebabble_string click to toggle source

Returns a BubbleBabble encoded version of a given string.

               static VALUE
rb_digest_s_bubblebabble(VALUE klass, VALUE str)
    return bubblebabble_str_new(str);
hexencode(string) → hexencoded_string click to toggle source

Generates a hex-encoded version of a given string.

               static VALUE
rb_digest_s_hexencode(VALUE klass, VALUE str)
    return hexencode_str_new(str);