module HMAC
  module SHA1
    def self.sign(key, message)
      mac = javax.crypto.Mac.getInstance("HmacSHA1")
      mac.init(javax.crypto.spec.SecretKeySpec.new(key.to_java_bytes, "HmacSHA1"))
      result = mac.doFinal(message.to_java_bytes)
      String.from_java_bytes(result).unpack('H*').join
    end    
  end
end