Class: JWA::Support::ConcatKDF

Inherits:
Object
  • Object
show all
Defined in:
lib/jwa/support/concat_kdf.rb

Instance Method Summary collapse

Constructor Details

#initialize(hash) ⇒ ConcatKDF

Returns a new instance of ConcatKDF.



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# File 'lib/jwa/support/concat_kdf.rb', line 4

def initialize(hash)
  @hash = hash
  @default_key_len = hash.size * 8
end

Instance Method Details

#derive_key(reps, key_data_len, z, other_info) ⇒ Object 



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# File 'lib/jwa/support/concat_kdf.rb', line 16

def derive_key(reps, key_data_len, z, other_info)
  key_material = ''
  data = z + other_info

  (1..reps).each do |n|
    concatenation = [n, data].pack('Na*')
    key_material += @hash.digest(concatenation)
  end

  key_material[0...key_data_len / 8]
end

#run(z, other_info, key_data_len = nil) ⇒ Object 



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# File 'lib/jwa/support/concat_kdf.rb', line 9

def run(z, other_info, key_data_len = nil)
  key_data_len ||= @default_key_len
  reps = (key_data_len / @default_key_len.to_f).ceil

  derive_key(reps, key_data_len, z, other_info)
end