Epithet makes SSH certificates easy

Epithet is an SSH certificate authority that replaces static authorized_keys with short-lived certificates (2-10 minutes) and authentication over OIDC. It creates on-demand SSH agents for each outbound connection, enabling real-time policy enforcement without touching your target hosts.

Quick start

1. Build epithet:

git clone https://github.com/epithet-ssh/epithet.git
cd epithet
make

2. Start the agent:

epithet agent --ca-url https://your-ca.example.com/

The agent discovers its OIDC issuer and client ID from the CA's Link header on the root response — nothing to configure locally.

3. Tag the hosts this profile should handle, then include the generated config (~/.ssh/config):

Host *.example.com
    Tag epithet

Include ~/.epithet/run/*/ssh-config.conf   # must come after Tag lines

4. SSH as normal:

ssh server.example.com

First connection authenticates through your browser (~2-5 seconds). In an SSH session, Epithet automatically uses the OIDC device flow instead. Subsequent connections reuse the refreshed token.

To scope the agent to a shell or another command, pass that command to the agent. It starts only after the broker is ready, and the agent exits when the command exits:

epithet agent zsh

The child uses the same generated ~/.ssh/config setup shown above. Use --login-method browser or --login-method device to override automatic login-method selection.

How it works

When you run ssh server.example.com, OpenSSH's Match tagged triggers epithet match for hosts you've tagged in your own ssh config. epithet match asks the broker for a certificate. The broker authenticates in-process via OIDC, requests a signed certificate from the CA (which checks policy in real time), and spins up a per-connection SSH agent with the short-lived certificate. See architecture for detailed sequence diagrams.

Components:

• Agent (epithet agent): Daemon managing OIDC authentication state and certificate lifecycle. Creates per-connection SSH agents.
• CA Server (epithet ca): Coordinates inventory authentication and policy evaluation, and signs SSH certificates after policy authorization.
• Inventory Server (epithet inventory): Validates OIDC tokens, maps directory IDs, and supplies user and host facts from static inventory, managed hosts, or a SCIM user directory. See the inventory guide.
• Policy Server (epithet policy): Evaluates normalized facts and makes authorization decisions - who can access what hosts as which users.

Documentation

• Architecture - How epithet works under the hood
• SCIM Provisioning - Pocket ID setup, directory lifecycle, and group bindings
• Policy Server Guide - Setup and configuration for the policy server
• Destination-bound Principals - Interoperable principal derivation protocol
• Authentication - The OIDC token contract and in-process auth flow
• OIDC Setup - Provider-specific OIDC configuration (Google, Okta, Azure AD)
• Releasing - Notes on cutting releases

Requires OpenSSH 9.4+ on the client (for Tag/Match tagged; see below).

License

Apache 2.0