# frozen_string_literal: false
#--
# sha2.rb - defines Digest::SHA2 class which wraps up the SHA256,
# SHA384, and SHA512 classes.
#++
# Copyright (c) 2006 Akinori MUSHA <knu@iDaemons.org>
#
# All rights reserved. You can redistribute and/or modify it under the same
# terms as Ruby.
#
# $Id$
require 'digest'
require 'digest/sha2/loader'
module Digest
#
# A meta digest provider class for SHA256, SHA384 and SHA512.
#
# FIPS 180-2 describes SHA2 family of digest algorithms. It defines
# three algorithms:
# * one which works on chunks of 512 bits and returns a 256-bit
# digest (SHA256),
# * one which works on chunks of 1024 bits and returns a 384-bit
# digest (SHA384),
# * and one which works on chunks of 1024 bits and returns a 512-bit
# digest (SHA512).
#
# ==Examples
# require 'digest'
#
# # Compute a complete digest
# Digest::SHA2.hexdigest 'abc' # => "ba7816bf8..."
# Digest::SHA2.new(256).hexdigest 'abc' # => "ba7816bf8..."
# Digest::SHA256.hexdigest 'abc' # => "ba7816bf8..."
#
# Digest::SHA2.new(384).hexdigest 'abc' # => "cb00753f4..."
# Digest::SHA384.hexdigest 'abc' # => "cb00753f4..."
#
# Digest::SHA2.new(512).hexdigest 'abc' # => "ddaf35a19..."
# Digest::SHA512.hexdigest 'abc' # => "ddaf35a19..."
#
# # Compute digest by chunks
# sha2 = Digest::SHA2.new # =>#<Digest::SHA2:256>
# sha2.update "ab"
# sha2 << "c" # alias for #update
# sha2.hexdigest # => "ba7816bf8..."
#
# # Use the same object to compute another digest
# sha2.reset
# sha2 << "message"
# sha2.hexdigest # => "ab530a13e..."
#
class SHA2 < Digest::Class
# call-seq:
# Digest::SHA2.new(bitlen = 256) -> digest_obj
#
# Create a new SHA2 hash object with a given bit length.
#
# Valid bit lengths are 256, 384 and 512.
def initialize(bitlen = 256)
case bitlen
when 256
@sha2 = Digest::SHA256.new
when 384
@sha2 = Digest::SHA384.new
when 512
@sha2 = Digest::SHA512.new
else
raise ArgumentError, "unsupported bit length: %s" % bitlen.inspect
end
@bitlen = bitlen
end
# call-seq:
# digest_obj.reset -> digest_obj
#
# Reset the digest to the initial state and return self.
def reset
@sha2.reset
self
end
# call-seq:
# digest_obj.update(string) -> digest_obj
# digest_obj << string -> digest_obj
#
# Update the digest using a given _string_ and return self.
def update(str)
@sha2.update(str)
self
end
alias << update
def finish # :nodoc:
@sha2.digest!
end
private :finish
# call-seq:
# digest_obj.block_length -> Integer
#
# Return the block length of the digest in bytes.
#
# Digest::SHA256.new.block_length * 8
# # => 512
# Digest::SHA384.new.block_length * 8
# # => 1024
# Digest::SHA512.new.block_length * 8
# # => 1024
def block_length
@sha2.block_length
end
# call-seq:
# digest_obj.digest_length -> Integer
#
# Return the length of the hash value (the digest) in bytes.
#
# Digest::SHA256.new.digest_length * 8
# # => 256
# Digest::SHA384.new.digest_length * 8
# # => 384
# Digest::SHA512.new.digest_length * 8
# # => 512
#
# For example, digests produced by Digest::SHA256 will always be 32 bytes
# (256 bits) in size.
def digest_length
@sha2.digest_length
end
def initialize_copy(other) # :nodoc:
@sha2 = other.instance_eval { @sha2.clone }
end
def inspect # :nodoc:
"#<%s:%d %s>" % [self.class.name, @bitlen, hexdigest]
end
end
end
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