certificates

README

Step Certificates

An online certificate authority and related tools for secure automated certificate management, so you can use TLS everywhere.

This repository is for step-ca, a certificate authority that exposes an API for automated certificate management. It also contains a golang SDK for interacting with step-ca programatically. However, you'll probably want to use the step command-line tool to operate step-ca and get certificates, instead of using this low-level SDK directly.

Questions? Find us on gitter.

Website | Documentation | Installation Guide | Getting Started | Contribution Guide

Features

It's super easy to get started and to operate step-ca thanks to streamlined initialization and safe, sane defaults. Get started in 15 minutes.

A private certificate authority you run yourself

• Issue client and server certificates to VMs, containers, devices, and people using internal hostnames and emails
• RFC5280 and CA/Browser Forum compliant certificates that work for TLS and HTTPS
• Choose key types (RSA, ECDSA, EdDSA) & lifetimes to suit your needs
• Short-lived certificates with fully automated enrollment, renewal, and revocation
• Fast, stable, and capable of high availability deployment using root federation and/or multiple intermediaries
• Operate as an online intermediate for an existing root CA
• Pluggable database backends for persistence
• Helm charts, autocert, and cert-manager integration for kubernetes

Lots of (automatable) ways to get certificates

• Single sign-on using Okta, GSuite, Active Directory, or any other OAuth OIDC identity provider
• Instance identity documents for VMs on AWS, GCP, and Azure
• Single-use short-lived tokens issued by your CD tool — Puppet, Chef, Ansible, Terraform, etc.
• Use an existing certificate from another CA (e.g., using a device certificate like Twilio's Trust OnBoard) coming soon

Your own private ACME Server

• Issue certificates using ACMEv2 (RFC8555), the protocol used by Let's Encrypt
• Great for using ACME in development & pre-production
• Supports the http-01, tls-alpn-01, and dns-01 ACME challenge types
• Works with any compliant ACME client including certbot, acme.sh, Caddy, and traefik
• Get certificates programmatically (e.g., in Go, Python, Node.js)

SSH Certificates

• Use certificate authentication for SSH: connect SSH to SSO, improve security, and eliminate warnings & errors
• Issue SSH user certificates using OAuth OIDC
• Issue SSH host certificates to cloud VMs using instance identity documents

Easy certificate management and automation via step CLI integration

• Generate key pairs where they're needed so private keys are never transmitted across the network
• Authenticate and obtain a certificate using any enrollment mechanism supported by step-ca
• Securely distribute root certificates and bootstrap PKI relying parties
• Renew and revoke certificates issued by step-ca
• Install root certificates so your CA is trusted by default (issue development certificates that work in browsers)
• Inspect and lint certificates

Motivation

Managing your own public key infrastructure (PKI) can be tedious and error prone. Good security hygiene is hard. Setting up simple PKI is out of reach for many small teams, and following best practices like proper certificate revocation and rolling is challenging even for experts.

Amongst numerous use cases, proper PKI makes it easy to use mTLS (mutual TLS) to improve security and to make it possible to connect services across the public internet. Unlike VPNs & SDNs, deploying and scaling mTLS is pretty easy. You're (hopefully) already using TLS, and your existing tools and standard libraries will provide most of what you need. If you know how to operate DNS and reverse proxies, you know how to operate mTLS infrastructure.

There's just one problem: you need certificates issued by your own certificate authority (CA). Building and operating a CA, issuing certificates, and making sure they're renewed before they expire is tricky. This project provides the infrastructure, automations, and workflows you'll need.

step certificates is part of smallstep's broader security architecture, which makes it much easier to implement good security practices early, and incrementally improve them as your system matures.

For more information and docs see the smallstep website and the blog post announcing this project.

Installation Guide

These instructions will install an OS specific version of the step-ca binary on your local machine.

While step is not required to run step-ca, it will make your life easier so you'll probably want to install it too.

Mac OS

Install step and step-ca together via Homebrew:

$ brew install step

# Test installation ...
$ step certificate inspect https://smallstep.com
Certificate:
    Data:
        Version: 3 (0x2)
        Serial Number: 326381749415081530968054238478851085504954 (0x3bf265673332db2d0c70e48a163fb7d11ba)
    Signature Algorithm: SHA256-RSA
        Issuer: C=US,O=Let's Encrypt,CN=Let's Encrypt Authority X3
...

Note: If you have installed step previously through the smallstep/smallstep tap you will need to run the following commands before installing:

$ brew untap smallstep/smallstep
$ brew uninstall step

Linux

Debian

1. [Optional] Install step.

   Download the latest Debian package from step releases:

   $ wget https://github.com/smallstep/cli/releases/download/vX.Y.Z/step-cli_X.Y.Z_amd64.deb
   

   Install the Debian package:

   $ sudo dpkg -i step-cli_X.Y.Z_amd64.deb
   

2. Install step-ca.

   Download the latest Debian package from releases:

   $ wget https://github.com/smallstep/certificates/releases/download/vX.Y.Z/step-certificates_X.Y.Z_amd64.deb
   

   Install the Debian package:

   $ sudo dpkg -i step-certificates_X.Y.Z_amd64.deb
   

Arch Linux

We are using the Arch User Repository to distribute step binaries for Arch Linux.

• [Optional] The step binary tarball can be found here.
• The step-ca binary tarball can be found here.

You can use pacman to install the packages.

RHEL/CentOS

1. [Optional] Install step.

   Download the latest Linux tarball from step releases:

   $ wget -O step-cli.tar.gz https://github.com/smallstep/cli/releases/download/vX.Y.Z/step_linux_X.Y.Z_amd64.tar.gz
   

   Install step by unzipping and copying the executable over to /usr/bin:

   $ tar -xf step-cli.tar.gz
   $ sudo cp step_X.Y.Z/bin/step /usr/bin
   

2. Install step-ca.

   Download the latest Linux package from releases:

   $ wget -O step-ca.tar.gz https://github.com/smallstep/cli/releases/download/vX.Y.Z/step_linux_X.Y.Z_amd64.tar.gz
   

   Install step-ca by unzipping and copying the executable over to /usr/bin:

   $ tar -xf step-ca.tar.gz
   $ sudo cp step-certificates_X.Y.Z/bin/step-ca /usr/bin
   

See the systemctl setup section for a guide on configuring step-ca as a daemon.

Kubernetes

We publish helm charts for easy installation on kubernetes:

helm install step-certificates

If you're using Kubernetes, make sure you check out autocert: a kubernetes add-on that builds on step certificates to automatically inject TLS/HTTPS certificates into your containers.

Test

$ step version
Smallstep CLI/0.10.0 (darwin/amd64)
Release Date: 2019-04-30 19:01 UTC

$ step-ca version
Smallstep CA/0.10.0 (darwin/amd64)
Release Date: 2019-04-30 19:02 UTC

Quickstart

In the following guide we'll run a simple hello server that requires clients to connect over an authorized and encrypted channel using HTTPS. step-ca will issue certificates to our server, allowing it to authenticate and encrypt communication. Let's get started!

Prerequisites

• step
• golang

Let's get started!

1. Run step ca init to create your CA's keys & certificates and configure step-ca:

$ step ca init
✔ What would you like to name your new PKI? (e.g. Smallstep): Example Inc.
✔ What DNS names or IP addresses would you like to add to your new CA? (e.g. ca.smallstep.com[,1.1.1.1,etc.]): localhost
✔ What address will your new CA listen at? (e.g. :443): 127.0.0.1:8080
✔ What would you like to name the first provisioner for your new CA? (e.g. you@smallstep.com): bob@example.com
✔ What do you want your password to be? [leave empty and we'll generate one]: abc123

Generating root certificate...
all done!

Generating intermediate certificate...
all done!

✔ Root certificate: /Users/bob/src/github.com/smallstep/step/.step/certs/root_ca.crt
✔ Root private key: /Users/bob/src/github.com/smallstep/step/.step/secrets/root_ca_key
✔ Root fingerprint: 702a094e239c9eec6f0dcd0a5f65e595bf7ed6614012825c5fe3d1ae1b2fd6ee
✔ Intermediate certificate: /Users/bob/src/github.com/smallstep/step/.step/certs/intermediate_ca.crt
✔ Intermediate private key: /Users/bob/src/github.com/smallstep/step/.step/secrets/intermediate_ca_key
✔ Default configuration: /Users/bob/src/github.com/smallstep/step/.step/config/defaults.json
✔ Certificate Authority configuration: /Users/bob/src/github.com/smallstep/step/.step/config/ca.json

Your PKI is ready to go. To generate certificates for individual services see 'step help ca'.

This command will:

• Generate password protected private keys for your CA to sign certificates
• Generate a root and intermediate signing certificate for your CA
• Create a JSON configuration file for step-ca (see getting started for details)

You can find these artifacts in $STEPPATH (or ~/.step by default).

2. Start step-ca:

You'll be prompted for your password from the previous step, to decrypt the CA's private signing key:

$ step-ca $(step path)/config/ca.json
Please enter the password to decrypt /Users/bob/src/github.com/smallstep/step/.step/secrets/intermediate_ca_key: abc123
2019/02/18 13:28:58 Serving HTTPS on 127.0.0.1:8080 ...

3. Copy our hello world golang server.

$ cat > srv.go <<EOF
package main

import (
    "net/http"
    "log"
)

func HiHandler(w http.ResponseWriter, req *http.Request) {
    w.Header().Set("Content-Type", "text/plain")
    w.Write([]byte("Hello, world!\n"))
}

func main() {
    http.HandleFunc("/hi", HiHandler)
    err := http.ListenAndServeTLS(":8443", "srv.crt", "srv.key", nil)
    if err != nil {
        log.Fatal(err)
    }
}
EOF

4. Get an identity for your server from the Step CA.

$ step ca certificate localhost srv.crt srv.key
✔ Key ID: rQxROEr7Kx9TNjSQBTETtsu3GKmuW9zm02dMXZ8GUEk (bob@example.com)
✔ Please enter the password to decrypt the provisioner key: abc123
✔ CA: https://localhost:8080/1.0/sign
✔ Certificate: srv.crt
✔ Private Key: srv.key

$ step certificate inspect --bundle srv.crt
Certificate:
    Data:
        Version: 3 (0x2)
        Serial Number: 140439335711218707689123407681832384336 (0x69a7a1d7f6f22f68059d2d9088307750)
    Signature Algorithm: ECDSA-SHA256
        Issuer: CN=Example Inc. Intermediate CA
        Validity
            Not Before: Feb 18 21:32:35 2019 UTC
            Not After : Feb 19 21:32:35 2019 UTC
        Subject: CN=localhost
...
Certificate:
    Data:
        Version: 3 (0x2)
        Serial Number: 207035091234452090159026162349261226844 (0x9bc18217bd560cf07db23178ed90835c)
    Signature Algorithm: ECDSA-SHA256
        Issuer: CN=Example Inc. Root CA
        Validity
            Not Before: Feb 18 21:27:21 2019 UTC
            Not After : Feb 15 21:27:21 2029 UTC
        Subject: CN=Example Inc. Intermediate CA
...

Note that step and step-ca handle details like certificate bundling for you.

5. Run the simple server.

$ go run srv.go &

6. Get the root certificate from the Step CA.

In a new Terminal window:

$ step ca root root.crt
The root certificate has been saved in root.crt.

7. Make an authenticated, encrypted curl request to your server using HTTP over TLS.

$ curl --cacert root.crt https://localhost:8443/hi
Hello, world!

All Done!

Check out the Getting Started guide for more examples and best practices on running Step CA in production.

Documentation

Documentation can be found in a handful of different places:

1. The docs sub-repo has an index of documentation and tutorials.

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. On the web at https://smallstep.com/docs/certificates.

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

The Future

We plan to build more tools that facilitate the use and management of zero trust networks.

• 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 what features you'd like to see - open issues or hit us on Twitter.

Further Reading

Check out the Getting Started guide for more examples and best practices on running Step CA in production.