Class: AliquotPay

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

Defined Under Namespace

Classes: Error, Util

Constant Summary collapse

EC_CURVE = 
'prime256v1'.freeze
DEFAULTS = 
{
  info: 'Google',
  recipient_id: 'merchant:0123456789',
}.freeze

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(protocol_version = :ECv2, root_key = nil) ⇒ AliquotPay

Returns a new instance of AliquotPay.



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# File 'lib/aliquot-pay.rb', line 28

def initialize(protocol_version = :ECv2, root_key = nil)
  @protocol_version = protocol_version
  if root_key
    @root_key = root_key
  end
end

Instance Attribute Details

#auth_method ⇒ Object

Returns the value of attribute auth_method.



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# File 'lib/aliquot-pay.rb', line 22

def auth_method
  @auth_method
end

#cleartext_message ⇒ Object

Returns the value of attribute cleartext_message.



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# File 'lib/aliquot-pay.rb', line 20

def cleartext_message
  @cleartext_message
end

#cryptogram ⇒ Object

Returns the value of attribute cryptogram.



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# File 'lib/aliquot-pay.rb', line 23

def cryptogram
  @cryptogram
end

#eci_indicator ⇒ Object

Returns the value of attribute eci_indicator.



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# File 'lib/aliquot-pay.rb', line 23

def eci_indicator
  @eci_indicator
end

#encrypted_message ⇒ Object

Returns the value of attribute encrypted_message.



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# File 'lib/aliquot-pay.rb', line 20

def encrypted_message
  @encrypted_message
end

#ephemeral_public_key ⇒ Object

Returns the value of attribute ephemeral_public_key.



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# File 'lib/aliquot-pay.rb', line 20

def ephemeral_public_key
  @ephemeral_public_key
end

#expiration_month ⇒ Object

Returns the value of attribute expiration_month.



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# File 'lib/aliquot-pay.rb', line 22

def expiration_month
  @expiration_month
end

#expiration_year ⇒ Object

Returns the value of attribute expiration_year.



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# File 'lib/aliquot-pay.rb', line 22

def expiration_year
  @expiration_year
end

#gateway_merchant_id ⇒ Object

Returns the value of attribute gateway_merchant_id.



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# File 'lib/aliquot-pay.rb', line 21

def gateway_merchant_id
  @gateway_merchant_id
end

#info ⇒ Object

Returns the value of attribute info.



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# File 'lib/aliquot-pay.rb', line 25

def info
  @info
end

#intermediate_key ⇒ Object

Returns the value of attribute intermediate_key.



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# File 'lib/aliquot-pay.rb', line 25

def intermediate_key
  @intermediate_key
end

#intermediate_signing_key ⇒ Object

Returns the value of attribute intermediate_signing_key.



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# File 'lib/aliquot-pay.rb', line 17

def intermediate_signing_key
  @intermediate_signing_key
end

#key_expiration ⇒ Object

Returns the value of attribute key_expiration.



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# File 'lib/aliquot-pay.rb', line 19

def key_expiration
  @key_expiration
end

#key_value ⇒ Object

Returns the value of attribute key_value.



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# File 'lib/aliquot-pay.rb', line 19

def key_value
  @key_value
end

#message_expiration ⇒ Object

Returns the value of attribute message_expiration.



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# File 'lib/aliquot-pay.rb', line 21

def message_expiration
  @message_expiration
end

#message_id ⇒ Object

Returns the value of attribute message_id.



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# File 'lib/aliquot-pay.rb', line 21

def message_id
  @message_id
end

#pan ⇒ Object

Returns the value of attribute pan.



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# File 'lib/aliquot-pay.rb', line 22

def pan
  @pan
end

#payment_method ⇒ Object

Returns the value of attribute payment_method.



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# File 'lib/aliquot-pay.rb', line 21

def payment_method
  @payment_method
end

#payment_method_details ⇒ Object

Returns the value of attribute payment_method_details.



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# File 'lib/aliquot-pay.rb', line 21

def payment_method_details
  @payment_method_details
end

#recipient ⇒ Object

Returns the value of attribute recipient.



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# File 'lib/aliquot-pay.rb', line 25

def recipient
  @recipient
end

#recipient_id ⇒ Object 



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# File 'lib/aliquot-pay.rb', line 227

def recipient_id
  @recipient_id ||= DEFAULTS[:recipient_id]
end

#root_key ⇒ Object

Returns the value of attribute root_key.



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# File 'lib/aliquot-pay.rb', line 25

def root_key
  @root_key
end

#shared_secret ⇒ Object 



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# File 'lib/aliquot-pay.rb', line 231

def shared_secret
  return Base64.strict_encode64(@shared_secret) if @shared_secret
  @shared_secret ||= Random.new.bytes(32)
  shared_secret
end

#signature ⇒ Object

Returns the value of attribute signature.



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# File 'lib/aliquot-pay.rb', line 17

def signature
  @signature
end

#signatures ⇒ Object

Returns the value of attribute signatures.



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# File 'lib/aliquot-pay.rb', line 18

def signatures
  @signatures
end

#signed_key ⇒ Object

Returns the value of attribute signed_key.



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# File 'lib/aliquot-pay.rb', line 18

def signed_key
  @signed_key
end

#signed_key_string ⇒ Object 



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# File 'lib/aliquot-pay.rb', line 163

def signed_key_string
  @signed_key_string ||= build_signed_key.to_json
end

#signed_message ⇒ Object

Returns the value of attribute signed_message.



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# File 'lib/aliquot-pay.rb', line 17

def signed_message
  @signed_message
end

#tag ⇒ Object

Returns the value of attribute tag.



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# File 'lib/aliquot-pay.rb', line 20

def tag
  @tag
end

#token ⇒ Object 



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# File 'lib/aliquot-pay.rb', line 35

def token
  build_token
end

Instance Method Details

#build_cleartext_message ⇒ Object 



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# File 'lib/aliquot-pay.rb', line 109

def build_cleartext_message
  return @cleartext_message if @cleartext_message

  default_message_id = Base64.strict_encode64(OpenSSL::Random.random_bytes(24))
  default_message_expiration = ((Time.now.to_f + 60 * 5) * 1000).round.to_s

  @cleartext_message = {
    'messageExpiration'    => @message_expiration || default_message_expiration,
    'messageId'            => @message_id || default_message_id,
    'paymentMethod'        => @payment_method || 'CARD',
    'paymentMethodDetails' => build_payment_method_details
  }

  if @protocol_version == :ECv2
    @cleartext_message.merge!(
      'gatewayMerchantId' => @gateway_merchant_id || 'SOME GATEWAY MERCHANT ID'
    )
  end

  @cleartext_message
end

#build_payment_method_details ⇒ Object 



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# File 'lib/aliquot-pay.rb', line 90

def build_payment_method_details
  return @payment_method_details if @payment_method_details
  value = {
    'pan'             => @pan              || '4111111111111111',
    'expirationYear'  => @expiration_year  || Time.now.year + 1,
    'expirationMonth' => @expiration_month || 12,
    'authMethod'      => @auth_method      || 'PAN_ONLY',
  }

  if @auth_method == 'CRYPTOGRAM_3DS'
    value.merge!(
      'cryptogram'   => @cryptogram    || 'SOME CRYPTOGRAM',
      'eciIndicator' => @eci_indicator || '05'
    )
  end

  value
end

#build_signature ⇒ Object 



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# File 'lib/aliquot-pay.rb', line 175

def build_signature
  return @signature if @signature
  key = case @protocol_version
        when :ECv1
          ensure_root_key
        when :ECv2
          ensure_intermediate_key
        end

  signature_string =
    signed_string_message = ['Google',
                             recipient_id,
                             @protocol_version.to_s,
                             signed_message_string].map do |str|
      [str.length].pack('V') + str
    end.join
  @signature = sign(key, signature_string)
end

#build_signatures ⇒ Object 



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# File 'lib/aliquot-pay.rb', line 194

def build_signatures
  return @signatures if @signatures

  signature_string =
    signed_key_signature = ['Google', 'ECv2', signed_key_string].map do |str|
      [str.to_s.length].pack('V') + str.to_s
    end.join

  @signatures = [sign(ensure_root_key, signature_string)]
end

#build_signed_key ⇒ Object 



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# File 'lib/aliquot-pay.rb', line 146

def build_signed_key
  return @signed_key if @signed_key
  ensure_intermediate_key

  if !@intermediate_key.private_key? && !@intermediate_key.public_key?
    fail 'Intermediate key must be public and private key'
  end

  default_key_value      = Base64.strict_encode64(@intermediate_key.to_der)
  default_key_expiration = "#{Time.now.to_i + 3600}000"

  @signed_key = {
    'keyExpiration' => @key_expiration || default_key_expiration,
    'keyValue'      => @key_value || default_key_value,
  }
end

#build_signed_message ⇒ Object 



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# File 'lib/aliquot-pay.rb', line 131

def build_signed_message
  return @signed_message if @signed_message

  signed_message = encrypt(build_cleartext_message.to_json)
  signed_message['encryptedMessage']   = @encrypted_message if @encrypted_message
  signed_message['ephemeralPublicKey'] = @ephemeral_public_key if @ephemeral_public_key
  signed_message['tag']                = @tag if @tag

  @signed_message = signed_message
end

#build_token ⇒ Object 



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# File 'lib/aliquot-pay.rb', line 205

def build_token
  return @token if @token
  res = {
    'protocolVersion' => @protocol_version.to_s,
    'signedMessage'   => @signed_message || signed_message_string,
    'signature'       => build_signature,
  }

  if @protocol_version == :ECv2
    intermediate = {
      'intermediateSigningKey' => @intermediate_signing_key || {
        'signedKey'  => signed_key_string,
        'signatures' => build_signatures,
      }
    }

    res.merge!(intermediate)
  end

  @token = res
end

#encrypt(cleartext_message) ⇒ Object 



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# File 'lib/aliquot-pay.rb', line 57

def encrypt(cleartext_message)
  @recipient ||= OpenSSL::PKey::EC.generate('prime256v1')
  @info ||= 'Google'

  eph = AliquotPay::Util.generate_ephemeral_key
  @shared_secret ||= AliquotPay::Util.generate_shared_secret(eph, @recipient.public_key)
  ss  = @shared_secret

  case @protocol_version
  when :ECv1
    cipher = OpenSSL::Cipher::AES128.new(:CTR)
  when :ECv2
    cipher = OpenSSL::Cipher::AES256.new(:CTR)
  else
    raise StandardError, "Invalid protocol_version #{protocol_version}"
  end

  keys = AliquotPay::Util.derive_keys(eph.public_key.to_bn.to_s(2), ss, @info, @protocol_version)

  cipher.encrypt
  cipher.key = keys[:aes_key]

  encrypted_message = cipher.update(cleartext_message) + cipher.final

  tag = AliquotPay::Util.calculate_tag(keys[:mac_key], encrypted_message)

  {
    'encryptedMessage'   => Base64.strict_encode64(encrypted_message),
    'ephemeralPublicKey' => Base64.strict_encode64(eph.public_key.to_bn.to_s(2)),
    'tag'                => Base64.strict_encode64(tag),
  }
end

#ensure_intermediate_key ⇒ Object 



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# File 'lib/aliquot-pay.rb', line 171

def ensure_intermediate_key
  @intermediate_key ||= OpenSSL::PKey::EC.generate(EC_CURVE)
end

#ensure_root_key ⇒ Object 



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# File 'lib/aliquot-pay.rb', line 167

def ensure_root_key
  @root_key ||= OpenSSL::PKey::EC.generate(EC_CURVE)
end

#extract_root_signing_keys ⇒ Object 



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# File 'lib/aliquot-pay.rb', line 39

def extract_root_signing_keys
  key = Base64.strict_encode64(ensure_root_key.to_der)
  {
    'keys' => [
      'protocolVersion' => @protocol_version,
      'keyValue'        => key,
    ]
  }.to_json
end

#sign(key, message) ⇒ Object 



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# File 'lib/aliquot-pay.rb', line 49

def sign(key, message)
  d = OpenSSL::Digest::SHA256.new
  def key.private?
    private_key?
  end
  Base64.strict_encode64(key.sign(d, message))
end

#signed_message_string ⇒ Object 



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# File 'lib/aliquot-pay.rb', line 142

def signed_message_string
  @signed_message_string ||= build_signed_message.to_json
end