Example AES256-GCM encryption with JWTs.

a256gcmkw.rb

# gem install jose

require 'jose'

payload = {
  'secret' => 'Cicadoidea'
}

##
# Encrypt your payload.
key = JOSE::JWK.from_oct SecureRandom.random_bytes 32 # Decrypt with this same key.
alg = 'A256GCMKW'
encrypted = JOSE::JWE.block_encrypt key, payload.to_json, {'alg' => alg, 'enc' => 'A256GCM'}
encrypted_payload = encrypted.compact

##
# Decrypt your payload.
decrypted_json_payload, decrypted = JOSE::JWE.block_decrypt key, encrypted_payload
decrypted_alg = decrypted.alg.algorithm
raise SecurityError, "alg `#{decrypted_alg}' does not match expected alg `#{alg}'" unless decrypted_alg == alg
decrypted_payload = JSON.parse decrypted_json_payload