hmac.rb
112 lines
| 2.7 KiB
| text/x-ruby
|
RubyLexer
Eric Davis
|
r2376 | # Copyright (C) 2001 Daiki Ueno <ueno@unixuser.org> | ||
| # This library is distributed under the terms of the Ruby license. | ||||
| # This module provides common interface to HMAC engines. | ||||
| # HMAC standard is documented in RFC 2104: | ||||
| # | ||||
| # H. Krawczyk et al., "HMAC: Keyed-Hashing for Message Authentication", | ||||
| # RFC 2104, February 1997 | ||||
| # | ||||
| # These APIs are inspired by JCE 1.2's javax.crypto.Mac interface. | ||||
| # | ||||
| # <URL:http://java.sun.com/security/JCE1.2/spec/apidoc/javax/crypto/Mac.html> | ||||
| module HMAC | ||||
| class Base | ||||
| def initialize(algorithm, block_size, output_length, key) | ||||
| @algorithm = algorithm | ||||
| @block_size = block_size | ||||
| @output_length = output_length | ||||
| @status = STATUS_UNDEFINED | ||||
| @key_xor_ipad = '' | ||||
| @key_xor_opad = '' | ||||
| set_key(key) unless key.nil? | ||||
| end | ||||
| private | ||||
| def check_status | ||||
| unless @status == STATUS_INITIALIZED | ||||
| raise RuntimeError, | ||||
| "The underlying hash algorithm has not yet been initialized." | ||||
| end | ||||
| end | ||||
| public | ||||
| def set_key(key) | ||||
| # If key is longer than the block size, apply hash function | ||||
| # to key and use the result as a real key. | ||||
| key = @algorithm.digest(key) if key.size > @block_size | ||||
| key_xor_ipad = "\x36" * @block_size | ||||
| key_xor_opad = "\x5C" * @block_size | ||||
| for i in 0 .. key.size - 1 | ||||
| key_xor_ipad[i] ^= key[i] | ||||
| key_xor_opad[i] ^= key[i] | ||||
| end | ||||
| @key_xor_ipad = key_xor_ipad | ||||
| @key_xor_opad = key_xor_opad | ||||
| @md = @algorithm.new | ||||
| @status = STATUS_INITIALIZED | ||||
| end | ||||
| def reset_key | ||||
| @key_xor_ipad.gsub!(/./, '?') | ||||
| @key_xor_opad.gsub!(/./, '?') | ||||
| @key_xor_ipad[0..-1] = '' | ||||
| @key_xor_opad[0..-1] = '' | ||||
| @status = STATUS_UNDEFINED | ||||
| end | ||||
| def update(text) | ||||
| check_status | ||||
| # perform inner H | ||||
| md = @algorithm.new | ||||
| md.update(@key_xor_ipad) | ||||
| md.update(text) | ||||
| str = md.digest | ||||
| # perform outer H | ||||
| md = @algorithm.new | ||||
| md.update(@key_xor_opad) | ||||
| md.update(str) | ||||
| @md = md | ||||
| end | ||||
| alias << update | ||||
| def digest | ||||
| check_status | ||||
| @md.digest | ||||
| end | ||||
| def hexdigest | ||||
| check_status | ||||
| @md.hexdigest | ||||
| end | ||||
| alias to_s hexdigest | ||||
| # These two class methods below are safer than using above | ||||
| # instance methods combinatorially because an instance will have | ||||
| # held a key even if it's no longer in use. | ||||
| def Base.digest(key, text) | ||||
| begin | ||||
| hmac = self.new(key) | ||||
| hmac.update(text) | ||||
| hmac.digest | ||||
| ensure | ||||
| hmac.reset_key | ||||
| end | ||||
| end | ||||
| def Base.hexdigest(key, text) | ||||
| begin | ||||
| hmac = self.new(key) | ||||
| hmac.update(text) | ||||
| hmac.hexdigest | ||||
| ensure | ||||
| hmac.reset_key | ||||
| end | ||||
| end | ||||
| private_class_method :new, :digest, :hexdigest | ||||
| end | ||||
| STATUS_UNDEFINED, STATUS_INITIALIZED = 0, 1 | ||||
| end | ||||