Encrypt URL Hash Parameters for communication between two domains

Any secure encryption scheme will do what you're describing. Since it sounds like both sides of the system are on servers you control (rather than in the client), that's straightforward. Create a random key and share it between the two servers, use AES-GCM to encrypt and decrypt the result, and base64-encode the encrypted data to transfer.

There are other secure encryption schemes, but AES-GCM is the easiest to use correctly for this kind of problem.