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.
# File lib/hmac.rb, line 96 def Base.digest(key, text) hmac = self.new(key) begin hmac.update(text) hmac.digest ensure hmac.reset_key end end
# File lib/hmac.rb, line 106 def Base.hexdigest(key, text) hmac = self.new(key) begin hmac.update(text) hmac.hexdigest ensure hmac.reset_key end end
# File lib/hmac.rb, line 23 def initialize(algorithm, block_size, output_length, key) @algorithm = algorithm @block_size = block_size @output_length = output_length @initialized = false @key_xor_ipad = '' @key_xor_opad = '' set_key(key) unless key.nil? end
# File lib/hmac.rb, line 82 def digest check_status @md.digest end
# File lib/hmac.rb, line 87 def hexdigest check_status @md.hexdigest end
# File lib/hmac.rb, line 59 def reset_key @key_xor_ipad.gsub!(/./, '?') @key_xor_opad.gsub!(/./, '?') @key_xor_ipad[0..-1] = '' @key_xor_opad[0..-1] = '' @initialized = false end
# File lib/hmac.rb, line 42 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 akey = key.unpack("C*") key_xor_ipad = ("\x36" * @block_size).unpack("C*") key_xor_opad = ("\x5C" * @block_size).unpack("C*") for i in 0 .. akey.size - 1 key_xor_ipad[i] ^= akey[i] key_xor_opad[i] ^= akey[i] end @key_xor_ipad = key_xor_ipad.pack("C*") @key_xor_opad = key_xor_opad.pack("C*") @md = @algorithm.new @initialized = true end
# File lib/hmac.rb, line 67 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
# File lib/hmac.rb, line 34 def check_status unless @initialized raise RuntimeError, "The underlying hash algorithm has not yet been initialized." end end