Class: IOTA::Crypto::Kerl

Inherits:
Object
  • Object
show all
Defined in:
lib/iota/crypto/kerl.rb

Constant Summary collapse

BIT_HASH_LENGTH = 
384
HASH_LENGTH = 
Curl::HASH_LENGTH

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Kerl

Returns a new instance of Kerl.



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# File 'lib/iota/crypto/kerl.rb', line 7

def initialize
  reset
end

Instance Method Details

#absorb(trits, offset = 0, length = nil) ⇒ Object 



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# File 'lib/iota/crypto/kerl.rb', line 21

def absorb(trits, offset = 0, length = nil)
  pad = trits.length % HASH_LENGTH != 0 ? trits.length % HASH_LENGTH : HASH_LENGTH
  trits.concat([0] * (HASH_LENGTH - pad))

  length = trits.length if length.nil?

  if length % HASH_LENGTH != 0 || length == 0
    raise StandardError,  "Illegal length provided"
  end

  while offset < length
    limit = [offset + HASH_LENGTH, length].min

    # If we're copying over a full chunk, zero last trit
    trits[limit - 1] = 0 if limit - offset == HASH_LENGTH

    signed_bytes = Converter.convertToBytes(trits[offset...limit])

    # Convert signed bytes into their equivalent unsigned representation
    # In order to use Python's built-in bytes type
    unsigned_bytes = signed_bytes.map{ |b| Converter.convertSign(b) }.pack('c*').force_encoding('UTF-8')

    @hasher.update(unsigned_bytes)

    offset += HASH_LENGTH
  end
end

#reset ⇒ Object 



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# File 'lib/iota/crypto/kerl.rb', line 11

def reset
  unless RUBY_PLATFORM =~ /java/
    require 'digest/sha3'
    @hasher = Digest::SHA3.new(BIT_HASH_LENGTH)
  else
    require "iota/crypto/sha3_ruby"
    @hasher = Digest::RubySHA3.new(BIT_HASH_LENGTH)
  end
end

#squeeze(trits, offset = 0, length = nil) ⇒ Object 



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# File 'lib/iota/crypto/kerl.rb', line 49

def squeeze(trits, offset = 0, length = nil)
  pad = trits.length % HASH_LENGTH != 0 ? trits.length % HASH_LENGTH : HASH_LENGTH
  trits.concat([0] * (HASH_LENGTH - pad))

  length = trits.length > 0 ? trits.length : HASH_LENGTH if length.nil?

  if length % HASH_LENGTH != 0 || length == 0
    raise StandardError,  "Illegal length provided"
  end

  while offset < length
    unsigned_hash =  @hasher.digest

    signed_hash = unsigned_hash.bytes.map { |b| Converter.convertSign(b) }

    trits_from_hash = Converter.convertToTrits(signed_hash)
    trits_from_hash[HASH_LENGTH - 1] = 0

    limit = [HASH_LENGTH, length - offset].min

    trits[offset...offset+limit] = trits_from_hash[0...limit]

    flipped_bytes = unsigned_hash.bytes.map{ |b| Converter.convertSign(~b)}.pack('c*').force_encoding('UTF-8')

    # Reset internal state before feeding back in
    reset
    @hasher.update(flipped_bytes)

    offset += HASH_LENGTH
  end
end