SSH key-based authentication is tried-and-true, but it lacks a true Public Key Infrastructure for key certification, revocation and expiration. Monkeysphere is a framework that uses the OpenPGP web of trust for these PKI functions. It can be used in both directions: for users to get validated host keys, and for hosts to authenticate users. Current monkeysphere SSH tools are designed to integrate with the OpenSSH implementation of the Secure Shell protocol.

Monkeysphere can also be used by a validation agent to validate TLS connections (e.g. https).