Chrome WebPush notifications payload encryption in ruby on rails

I have implemented webpush notification in ruby on rails using ruby(version = 1.9) and rails(version = 3.2) but it shows nil data in notification because it needs some encryption.

As per the google document, I have to encrypt payload data in given format only and then it will work. So I tried a gem webpush but the gem has only been written to support ruby 2.3. Then I tried to implement elliptic cryptography but again I'm getting nil in the gcm response So I am not sure about my encryption as well.

Thanks in advance!