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# == License
#
# Copyright (c) 2006 Akinori MUSHA <knu@iDaemons.org>
#
# Documentation by Akinori MUSHA
#
# All rights reserved. You can redistribute and/or modify it under
# the same terms as Ruby.
#
# $Id$
#
warn "use of the experimetal library 'digest/hmac' is discouraged; require 'openssl' and use OpenSSL::HMAC instead." if $VERBOSE
require 'digest'
module Digest
# = digest/hmac.rb
#
# An experimental implementation of HMAC keyed-hashing algorithm
#
# == Overview
#
# CAUTION: Use of this library is discouraged, because this
# implementation was meant to be experimental but somehow got into the
# 1.9 series without being noticed. Please use OpenSSL::HMAC in the
# "openssl" library instead.
#
# == Examples
#
# require 'digest/hmac'
#
# # one-liner example
# puts Digest::HMAC.hexdigest("data", "hash key", Digest::SHA1)
#
# # rather longer one
# hmac = Digest::HMAC.new("foo", Digest::RMD160)
#
# buf = ""
# while stream.read(16384, buf)
# hmac.update(buf)
# end
#
# puts hmac.hexdigest
#
class HMAC < Digest::Class
# Creates a Digest::HMAC instance.
def initialize(key, digester)
@md = digester.new
block_len = @md.block_length
if key.bytesize > block_len
key = @md.digest(key)
end
ipad = Array.new(block_len, 0x36)
opad = Array.new(block_len, 0x5c)
key.bytes.each_with_index { |c, i|
ipad[i] ^= c
opad[i] ^= c
}
@key = key.freeze
@ipad = ipad.pack('C*').freeze
@opad = opad.pack('C*').freeze
@md.update(@ipad)
end
def initialize_copy(other) # :nodoc:
@md = other.instance_eval { @md.clone }
end
# call-seq:
# hmac.update(string) -> hmac
# hmac << string -> hmac
#
# Updates the hmac using a given +string+ and returns self.
def update(text)
@md.update(text)
self
end
alias << update
# call-seq:
# hmac.reset -> hmac
#
# Resets the hmac to the initial state and returns self.
def reset
@md.reset
@md.update(@ipad)
self
end
def finish # :nodoc:
d = @md.digest!
@md.update(@opad)
@md.update(d)
@md.digest!
end
private :finish
# call-seq:
# hmac.digest_length -> Integer
#
# Returns the length in bytes of the hash value of the digest.
def digest_length
@md.digest_length
end
# call-seq:
# hmac.block_length -> Integer
#
# Returns the block length in bytes of the hmac.
def block_length
@md.block_length
end
# call-seq:
# hmac.inspect -> string
#
# Creates a printable version of the hmac object.
def inspect
sprintf('#<%s: key=%s, digest=%s>', self.class.name, @key.inspect, @md.inspect.sub(/^\#<(.*)>$/) { $1 });
end
end
end
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