No, this is for symmetrical encryption. So think something like AES, but where the 'distributor' encrypts something, gives you a key and an algorithm, and you

No, this is for symmetrical encryption. So think something like AES, but where the 'distributor' encrypts something, gives you a key and an algorithm, and you can decrypt it. But you cannot use the same algorithm to encrypt to send back anything. For the life of me I can't remember where I read it (which book), so have never been able to dig into it more.