Class: RbNaCl::Hash::Blake2b

Inherits:
Object
  • Object
show all
Extended by:
Sodium
Defined in:
lib/rbnacl/hash/blake2b.rb

Overview

The Blake2b hash function

Blake2b is based on Blake, a SHA3 finalist which was snubbed in favor of Keccak, a much slower hash function but one sufficiently different from SHA2 to let the SHA3 judges panel sleep easy. Back in the real world, it'd be great if we can calculate hashes quickly if possible.

Blake2b provides for up to 64-bit digests and also supports a keyed mode similar to HMAC

Constant Summary collapse

EMPTY_PERSONAL = 
("\0" * PERSONALBYTES).freeze
EMPTY_SALT = 
("\0" * SALTBYTES).freeze

Instance Method Summary collapse

Methods included from Sodium

primitive, sodium_constant, sodium_function, sodium_function_with_return_code, sodium_primitive, sodium_type

Constructor Details

#initialize(opts = {}) ⇒ RbNaCl::Hash::Blake2b

Create a new Blake2b hash object

Parameters:

  • opts (Hash) (defaults to: {}) —

    Blake2b configuration

Options Hash (opts):

  • :key (String) —

    for Blake2b keyed mode

  • :digest_size (Integer) —

    size of output digest in bytes

  • :salt (String) —

    Provide a salt to support randomised hashing. This is mixed into the parameters block to start the hashing.

  • :personal (Personal) —

    Provide personalisation string to allow pinning a hash for a particular purpose. This is mixed into the parameters block to start the hashing

Raises:



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# File 'lib/rbnacl/hash/blake2b.rb', line 47

def initialize(opts = {})
  @key = opts.fetch(:key, nil)

  if @key
    @key_size = @key.bytesize
    raise LengthError, "key too short" if @key_size < KEYBYTES_MIN
    raise LengthError, "key too long"  if @key_size > KEYBYTES_MAX
  else
    @key_size = 0
  end

  @digest_size = opts.fetch(:digest_size, BYTES_MAX)
  raise LengthError, "digest size too short" if @digest_size < BYTES_MIN
  raise LengthError, "digest size too long"  if @digest_size > BYTES_MAX

  @personal = opts.fetch(:personal, EMPTY_PERSONAL)
  @personal = Util.zero_pad(PERSONALBYTES, @personal)

  @salt     = opts.fetch(:salt, EMPTY_SALT)
  @salt     = Util.zero_pad(SALTBYTES, @salt)
end

Instance Method Details

#digest(message) ⇒ String

Calculate a Blake2b digest

Parameters:

  • message (String) —

    Message to be hashed

Returns:

  • (String) —

    Blake2b digest of the string as raw bytes



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# File 'lib/rbnacl/hash/blake2b.rb', line 74

def digest(message)
  digest = Util.zeros(@digest_size)
  self.class.generichash_blake2b(digest, @digest_size, message, message.bytesize, @key, @key_size, @salt, @personal) ||
    raise(CryptoError, "Hashing failed!")
  digest
end