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..."
# File tmp/rubies/ruby-3.3.0/ext/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
Create a new SHA2 hash object with a given bit length.
Valid bit lengths are 256, 384 and 512.
# File tmp/rubies/ruby-3.3.0/ext/digest/sha2/lib/sha2.rb, line 112
def block_length
@sha2.block_length
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 tmp/rubies/ruby-3.3.0/ext/digest/sha2/lib/sha2.rb, line 130
def digest_length
@sha2.digest_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 tmp/rubies/ruby-3.3.0/ext/digest/sha2/lib/sha2.rb, line 79
def reset
@sha2.reset
self
end
Reset the digest to the initial state and return self.
# File tmp/rubies/ruby-3.3.0/ext/digest/sha2/lib/sha2.rb, line 89
def update(str)
@sha2.update(str)
self
end
Update the digest using a given string and return self.