Class: AliquotPay::Util

Inherits:
Object
  • Object
show all
Defined in:
lib/aliquot-pay/util.rb

Class Method Summary collapse

Class Method Details

.calculate_tag(mac_key, encrypted_message) ⇒ Object 



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# File 'lib/aliquot-pay/util.rb', line 38

def self.calculate_tag(mac_key, encrypted_message)
  digest = OpenSSL::Digest::SHA256.new
  OpenSSL::HMAC.digest(digest, mac_key, encrypted_message)
end

.derive_keys(ephemeral_public_key, shared_secret, info, protocol_version = :ECv2) ⇒ Object 



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# File 'lib/aliquot-pay/util.rb', line 14

def self.derive_keys(ephemeral_public_key, shared_secret, info, protocol_version = :ECv2)
  case protocol_version
  when :ECv1
    key_length = 16
  when :ECv2
    key_length = 32
  else
    raise StandardError, "invalid protocol_version #{protocol_version}"
  end

  input_keying_material = ephemeral_public_key + shared_secret
  if OpenSSL.const_defined?(:KDF) && OpenSSL::KDF.respond_to?(:hkdf)
    h = OpenSSL::Digest::SHA256.new
    hbytes = OpenSSL::KDF.hkdf(input_keying_material, hash: h, salt: '', length: key_length * 2, info: info)
  else
    hbytes = HKDF.new(input_keying_material, algorithm: 'SHA256', info: info).next_bytes(key_length * 2)
  end

  {
    aes_key: hbytes[0, key_length],
    mac_key: hbytes[key_length, key_length],
  }
end

.generate_ephemeral_key ⇒ Object 



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# File 'lib/aliquot-pay/util.rb', line 6

def self.generate_ephemeral_key
  OpenSSL::PKey::EC.generate(AliquotPay::EC_CURVE)
end

.generate_shared_secret(private_key, public_key) ⇒ Object 



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# File 'lib/aliquot-pay/util.rb', line 10

def self.generate_shared_secret(private_key, public_key)
  private_key.dh_compute_key(public_key)
end