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).
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..."
Create a new SHA2 hash object with a given bit length.
Valid bit lengths are 256, 384 and 512.
# File digest/sha2/lib/sha2.rb, line 61 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
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
# File digest/sha2/lib/sha2.rb, line 112 def block_length @sha2.block_length end
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.
# File digest/sha2/lib/sha2.rb, line 130 def digest_length @sha2.digest_length end
Reset the digest to the initial state and return self.
# File digest/sha2/lib/sha2.rb, line 79 def reset @sha2.reset self end
Update the digest using a given string and return self.
# File digest/sha2/lib/sha2.rb, line 89 def update(str) @sha2.update(str) self end