# What communications security protocols exist that aren't based on PKC?

Lets say that you have two devices that need to communicate in a secure manner. These devices can share secrets before communication takes place (This sharing of secrets occurs over another secure channel). Furthermore, these devices can not use public key cryptography.

Assuming that underlying cryptographic primitives are soundly implemented, what communications security protocols exist that can secure such communications at both the message level (authentication, encryption, and integrity) and the protocol level (guard against replay attacks and so on)?

• TLS-PSK without DHE/ECDHE. – SEJPM Nov 6 '15 at 11:55
• @SEJPM Thank you. TLS_PSK is exactly what I was hoping for. Consider posting your reply as an answer (I am not able to upvote it, unfortunately. However, I canl mark it an an accepted answer if no other, more-complete answer is posted.) – jougasaki Nov 6 '15 at 12:15

TLS-PSK offers PKC aided and non-aided key-exchanges, with the former being recognizable by the DHE, ECDHE, RSA parts in their names. This means you want to look for the TLS_PSK_WITH_* cipher suites.
In particular I'd recommend you using TLS_PSK_WITH_AES_128_GCM_SHA256 (or the 256/384 version thereof). If your platform doesn't offer SHA-2 and / or AES-GCM your best choice would be TLS_PSK_WITH_AES_128_CBC_SHA.