step-ca is an online certificate authority for secure, automated certificate management. It's the server counterpart to the step CLI tool.

You can use it to:

• Issue X.509 certificates for your internal infrastructure:
  • HTTPS certificates that work in browsers (RFC5280 and CA/Browser Forum compliance)
  • TLS certificates for VMs, containers, APIs, mobile clients, database connections, printers, wifi networks, toaster ovens...
  • Client certificates to enable mutual TLS (mTLS) in your infra. mTLS is an optional feature in TLS where both client and server authenticate each other. Why add the complexity of a VPN when you can safely use mTLS over the public internet?
• Issue SSH certificates:
  • For people, in exchange for single sign-on ID tokens
  • For hosts, in exchange for cloud instance identity documents
• Easily automate certificate management:
  • It's an ACME v2 server
  • It has a JSON API
  • It comes with a Go wrapper
  • ... and there's a command-line client you can use in scripts!

Whatever your use case, step-ca is easy to use and hard to misuse, thanks to safe, sane defaults.

Questions? Find us in Discussions.

Website | Documentation | Installation | Getting Started | Contributor's Guide

Setting up a public key infrastructure (PKI) is out of reach for many small teams. step-ca makes it easier.

• Choose key types (RSA, ECDSA, EdDSA) and lifetimes to suit your needs
• Short-lived certificates with automated enrollment, renewal, and passive revocation
• Capable of high availability (HA) deployment using root federation and/or multiple intermediaries
• Can operate as an online intermediate CA for an existing root CA
• Badger, BoltDB, and MySQL database backends

There are several ways to authorize a request with the CA and establish a chain of trust that suits your flow.

You can issue certificates in exchange for:

• ACME challenge responses from any ACMEv2 client
• OAuth OIDC single sign-on tokens, eg:
  • ID tokens from Okta, GSuite, Azure AD, Auth0.
  • ID tokens from an OAuth OIDC service that you host, like Keycloak or Dex
• Cloud instance identity documents, for VMs on AWS, GCP, and Azure
• Single-use, short-lived JWK tokens issued by your CD tool — Puppet, Chef, Ansible, Terraform, etc.
• A trusted X.509 certificate (X5C provisioner)
• Expiring SSH host certificates needing rotation (the SSHPOP provisioner)
• Learn more in our provisioner documentation

ACME is the protocol used by Let's Encrypt to automate the issuance of HTTPS certificates. It's super easy to issue certificates to any ACMEv2 (RFC8555) client.

• Use ACME in development & pre-production

• Supports the most popular ACME challenge types:

  • For http-01, place a token at a well-known URL to prove that you control the web server
  • For dns-01, add a TXT record to prove that you control the DNS record set
  • For tls-alpn-01, respond to the challenge at the TLS layer (as Caddy does) to prove that you control the web server

• Works with any ACME client. We've written examples for:

  • certbot
  • acme.sh
  • Caddy
  • Traefik
  • Apache
  • nginx

• Get certificates programmatically using ACME, using these libraries:

  • lego for Golang (example usage)
  • certbot's acme module for Python (example usage)
  • acme-client for Node.js (example usage)

• Our own step CLI tool is also an ACME client!

• See our ACME tutorial for more

• Delegate SSH authentication to step-ca by using SSH certificates instead of public keys and authorized_keys files
• For user certificates, connect SSH to your single sign-on provider, to improve security with short-lived certificates and MFA (or other security policies) via any OAuth OIDC provider.
• For host certificates, improve security, eliminate TOFU warnings, and set up automated host certificate renewal.

• Generate key pairs where they're needed so private keys are never transmitted across the network
• Authenticate and obtain a certificate using any provisioner supported by step-ca
• Securely distribute root certificates and bootstrap PKI relying parties
• Renew and revoke certificates issued by step-ca
• Install root certificates on your machine and browsers, so your CA is trusted
• Inspect and lint certificates

See our installation docs here.

Documentation can be found in a handful of different places:

1. On the web at https://smallstep.com/docs/step-ca.

2. On the command line with step help ca xxx where xxx is the subcommand you are interested in. Ex: step help ca provisioner list.

3. In your browser, by running step help --http=:8080 ca from the command line and visiting http://localhost:8080.

4. The docs folder is being deprecated, but it still has some documentation and tutorials.

• Tell us what you like and don't like about managing your PKI - we're eager to help solve problems in this space.
• Tell us about a feature you'd like to see! Add a feature request Issue, ask on Discussions, or hit us up on Twitter.