hmac.rb

module Webhooks
  class HmacSignature
    DIGEST = OpenSSL::Digest.new('sha1').freeze

    def initialize(secret_token, payload_body)
      @secret_token = secret_token
      @payload_body = payload_body.to_s
    end

    def generate
      return unless secret_token
      hmac = OpenSSL::HMAC.hexdigest(DIGEST, secret_token, payload_body)

      "sha1=#{hmac}"
    end

    def verify_signature(received_signature)
      signature = 'sha1=' + OpenSSL::HMAC.hexdigest(DIGEST, secret_token, payload_body)
      Rack::Utils.secure_compare(signature, received_signature) ? true : false
    end

    attr_reader :secret_token, :payload_body
  end
end