install

Additional install commands

macOS

Homebrewverified · 100%

brew install opkssh

provider-native install command

overview

Package summary

Enables SSH to be used with OpenID Connect

Project links

Commands and aliases

opkssh

history

Project history and usage

opkssh, short for OpenPubkey SSH, brings OpenID Connect identity into ordinary SSH login flows. It lets administrators authorize identities such as email addresses and groups instead of distributing long-lived SSH public keys, while still using the stock SSH client and server protocol.

Project history

The tool is built on OpenPubkey, a protocol described in a 2023 IACR paper that binds a user-held public key into an OpenID Connect ID Token, turning that token into what the authors call a PK Token. opkssh applies that idea to SSH by generating an SSH key/certificate carrying the PK Token and by configuring sshd to verify it.

Cloudflare announced on 2025-03-25 that it had open-sourced OPKSSH under the OpenPubkey project. The announcement says the OpenPubkey protocol became an open source Linux Foundation project in 2023, while OPKSSH had remained closed source under BastionZero, later Cloudflare, until the donation.

Adoption history

The project moved quickly into normal package-manager territory for a security tool: its metadata lists packages for Homebrew, Debian development packages, Fedora, Nix, and Windows winget, and the README documents Homebrew, winget, Chocolatey, Nix, and direct binary installs.

How it is used

A user runs `opkssh login`, authenticates in a browser with an OpenID Provider, and receives a generated SSH key whose public side contains the OpenPubkey token. On the server, opkssh is used through sshd's `AuthorizedKeysCommand` hook, so the verifier can extract the PK Token, validate the identity provider signature and expiry, and map the identity to a Unix or Windows account.

Operators use `/etc/opk/providers` to choose trusted OpenID Providers and client IDs, and `/etc/opk/auth_id` or per-user equivalents to authorize identities, subjects, or group claims. The design gives SSH administrators an SSO-style access list without changing the SSH wire protocol.

Why package nerds care

opkssh is interesting because it packages an identity-protocol research result as a small CLI that plugs into a decades-old Unix extension point. For package nerds, the notable bit is not a new daemon or a replacement SSH stack, but a cross-platform binary that makes SSH key lifecycle policy distributable through package managers.

Timeline

2023: OpenPubkey is published as a protocol for binding OpenID Connect ID Tokens to user-held public keys.
2023: OpenPubkey becomes an open source Linux Foundation project, according to Cloudflare's OPKSSH open-source announcement.
2025-03-25: Cloudflare announces that OPKSSH has been donated to the OpenPubkey project and released as open source.

Related projects

OpenPubkey is the underlying protocol. OpenSSH supplies the client/server behavior and `AuthorizedKeysCommand` integration point. The broader ecosystem includes OpenID Providers such as Google, Microsoft Entra ID, GitLab, Keycloak, Authentik, Authelia, Zitadel, and similar OIDC services.

Sources

security posture

Risk level: blue

broad file, network, media, or database tool signal.

Risk classifier

blue risk · medium confidence · tool

Why

broad file, network, media, or database tool signal

Signals

text:ssh

Install behavior

No Homebrew bottle metadata was recorded.

Recommended review

Before unattended agent use, check whether the tool reads plaintext credentials, writes remote state, publishes artifacts, or shells out to plugins.

local files

Configuration and credential file locations

These source-backed paths show where this package keeps local settings or durable credentials. Automic Vault can use them as review targets for secret scanning, migration, and command approval.

Configuration files

Config paths the tool may read or write during local use.

Linux: /etc/opk/providers/etc/opk/auth_id/etc/opk/policy.d/*.yml
Unix: ~/.opk/config.yml
Windows: %ProgramData%\opk\providers%ProgramData%\opk\auth_id

executables

Installed executables

Command	Kind	Exposure	Note
`opkssh`	executable	indexed executable	Discovered from the local executable index.

freshness

Version and freshness

These signals separate page generation age, package-manager activity, and upstream release comparison. Version lag is warned only when an evidence URL and comparable versions are present.

page generated2026-08-03

manager version0.16.0

manager updated2026-07-27

local dataunknown

upstreamnot available

latest detectednot detected

okNo freshness warnings were generated.

install metadata

Package metadata

Package key	brew:opkssh
Version	0.16.0
Package manager	Homebrew
Homepage	https://eprint.iacr.org/2023/296
Repository	https://github.com/openpubkey/opkssh
Last updated	2026-07-27T23:46:52+02:00
Pulse	updated
Bottle	not recorded
Service	none declared

package graph

Links come from deterministic package relationships, av.db category and tag curation, ecosystem matches, and package hub membership.

source trail

Generated from repository data

This page is generated by av-web from the private package SQLite artifact built by scripts/generate-pkg-sqlite.py.

Combined YAML source

View the package source record on GitHub.

combined/opkssh.yml

Used sources

Geiger risk classifier
Nucleus package database
curated configuration and credential file locations
curated package history
pkgdb category and tag curation

Install opkssh with Homebrew