For 10 points, name this process by which information is made unreadable except by those possessing a "key."
This process can be undertaken by two parties with no prior knowledge of one another using the Diffie-Hellman protocol. One algorithm for doing this relies on taking the Euler totient (toh SHUNT) function of the product of p and q. The difficulty of prime factorization is central to the (*) RSA algorithm for doing this process. The information transmitted via this process is called "plaintext," and the algorithms that do it are called "ciphers." For 10 points, name this process by which information is made unreadable except by those possessing a "key."
This process can be undertaken by two parties with no prior knowledge of one another using the Diffie-Hellman protocol.
{encryption} [or {cryptography} or word forms; prompt on {encoding}]