Protocol Key Negotiation

In some aspects, a cryptography method includes executing, by operation of a first computing device associated with a first entity, a first handshake process with a second entity according to a first handshake protocol to establish a first symmetric encryption key for a first encryption protocol; executing, by operation of the first computing device, a second handshake process with the second entity to establish a second symmetric encryption key for a second encryption protocol. Executing the second handshake process includes: generating second handshake data according to a second handshake protocol; encrypting the second handshake data using the first symmetric encryption key with the first encryption protocol; and sending the encrypted second handshake data to a second computing device associated with the second entity; and using the second symmetric encryption key and the second encryption protocol for single-encrypted communication over a communication channel between the first and second entities.