Module: Buckaruby::Signature

Defined in:
lib/buckaruby/signature.rb

Overview

Calculate a signature based on the parameters of the payment request or response. -> see BPE 3.0 Gateway NVP, chapter 4 'Digital Signature'

Constant Summary collapse

CHAR_ORDER =

Excerpt from the Buckaroo documentation, chapter 4 'Digital Signature':

In the payment engine, the used lexical sort algorithm uses the following order:
symbols first, then numbers, then case insensitive letters. Also, a shorter string
that is identical to the beginning of a longer string, comes before the longer string.
Take for example the following, comma separated, list which has been sorted:
  a_a, a0, a0a, a1a, aaA, aab, aba, aCa

'_01234567890abcdefghijklmnopqrstuvwxyz'

Class Method Summary collapse

Class Method Details

.generate(config, params) ⇒ Object 



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# File 'lib/buckaruby/signature.rb', line 11

def generate(config, params)
  string = generate_params_string(config.secret, params)

  case config.hash_method
  when :sha1
    Digest::SHA1.hexdigest(string)
  when :sha256
    Digest::SHA256.hexdigest(string)
  when :sha512
    Digest::SHA512.hexdigest(string)
  else
    raise ArgumentError, "Invalid hash method provided: #{config.hash_method}"
  end
end

.generate_params_string(secret, params) ⇒ Object 



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# File 'lib/buckaruby/signature.rb', line 26

def generate_params_string(secret, params)
  sign_params = params.select { |key, _value| key.to_s.upcase.start_with?('BRQ_', 'ADD_', 'CUST_') && key.to_s.casecmp('BRQ_SIGNATURE').nonzero? }
  sign_params = order_signature_params(sign_params)

  string = sign_params.map { |param| "#{param[0]}=#{param[1]}" }.join
  string << secret
  string
end

.order_signature_params(params) ⇒ Object 



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# File 'lib/buckaruby/signature.rb', line 43

def order_signature_params(params)
  params.sort_by do |key, _value|
    key.to_s.downcase.each_char.map { |c| CHAR_ORDER.index(c) }
  end
end

.safe_equals?(signature, other_signature) ⇒ Boolean

Constant time string comparison.

Returns:

  • (Boolean) 


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# File 'lib/buckaruby/signature.rb', line 60

def safe_equals?(signature, other_signature)
  check = signature.bytesize ^ other_signature.bytesize
  signature.bytes.zip(other_signature.bytes) { |x, y| check |= x ^ y.to_i }
  check.zero?
end

.verify!(config, params) ⇒ Object

Check the signature from the Buckaroo response with our generated signature.



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# File 'lib/buckaruby/signature.rb', line 50

def verify!(config, params)
  sent_signature = params.find { |key, _value| key.to_s.casecmp('BRQ_SIGNATURE').zero? }&.last
  generated_signature = Signature.generate(config, params)

  if sent_signature.nil? || generated_signature.nil? || !safe_equals?(sent_signature, generated_signature)
    raise SignatureException.new(sent_signature, generated_signature)
  end
end