openssl sha256 signature

test.rb

require 'openssl'
require "base64"

DELIMITER = ":cba_signature_delimiter:"

# Airtasker sends encoded data
key = OpenSSL::PKey::RSA.new(File.read('private.pem'))
timestamp = '31480574670' # unix time stamp in utc timezone
signature = key.sign(OpenSSL::Digest::SHA256.new, timestamp)
data = timestamp + DELIMITER + Base64.strict_encode64(signature)
encoded_data = Base64.strict_encode64(data)

puts encoded_data

# CBA decode the encoded data and verify
decoded_data = Base64.decode64(encoded_data)
decoded_timestamp, encoded_signature = decoded_data.split(DELIMITER)
decoded_signature = Base64.decode64(encoded_signature)

pubkey = OpenSSL::PKey::RSA.new(File.read('public.pem'))

if pubkey.verify(OpenSSL::Digest::SHA256.new, decoded_signature, decoded_timestamp)
  puts 'the signature is valid'
else
  puts 'the signature is invalid'
end