require 'openssl'
require 'rack' # gem install rack

test_payload_body='{"message":"test content"}'
test_signature_to_compare_with='sha1=33a08e9b5e9c8d5e944d9288e9b499abb298344d'

def generate_signature(secret_token, payload_body)
    return 'sha1=' + OpenSSL::HMAC.hexdigest(OpenSSL::Digest.new('sha1'), secret_token, payload_body)
end

def verify_signature(secret_token, payload_body, signature_to_compare_with)
    signature = generate_signature(secret_token, payload_body)
    return Rack::Utils.secure_compare(signature, signature_to_compare_with)
end

puts "signature match? : #{verify_signature(ENV['SECRET_TOKEN'], test_payload_body, test_signature_to_compare_with)}"