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Step Certificates

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

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

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Animated terminal showing step certificates in practice

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.

Connect it all with mTLS

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 Step website and the blog post announcing Step Certificate Authority.

🆕 Autocert

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.

Installation Guide

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

NOTE: While step is not required to run the Step Certificate Authority (CA) we strongly recommend installing both step cli and step certificates because the Step CA is much easier to initialize, manage, and debug using the step cli toolkit.

Mac OS

Install step via Homebrew. The Homebrew Formula installs both step cli and step certificates.


$ 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 cli.

    Download the latest Debian package from step cli releases:

    $ wget https://github.com/smallstep/cli/releases/download/X.Y.Z/step_X.Y.Z_amd64.deb

    Install the Debian package:

    $ sudo dpkg -i step_X.Y.Z_amd64.deb

  2. Install step certificates.

    Download the latest Debian package from step certificates releases:

    $ wget https://github.com/smallstep/certificates/releases/download/X.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-cli binary tarball can be found here.
  • The step-ca binary tarball can be found here.

You can use pacman to install the packages.

Test


$ step version
Smallstep CLI/0.8.5 (darwin/amd64)
Release Date: 2019-02-13 22:17 UTC

$ step-ca version
Smallstep CA/0.8.4 (darwin/amd64)
Release Date: 2019-02-18 18:56 UTC

Quickstart

In the following guide we'll run a simple hello server that requires clients to connect over an authorized and encrypted channel (HTTP over TLS). The Step Certificate Authority (CA) will issue an identity dial tone to our server enabling it to authenticate and encrypt communication. Let's get started!

Prerequisites

Let's get started!

  1. Initialize and run the Step CA.

    step ca init initializes the CA and accomplishes two tasks.

    1. Generate a Public Key Infrastructure (PKI) with Root and Intermediate X.509 Certificates and private keys.

      The root X.509 Certificate is a fancy public key that will be distributed to clients enabling them to authenticate all certificates generated by your PKI. The root private key should be kept in a very private place - but as this is just a demo we won't worry about that right now (more info on storing sensitive data). The intermediate private key will be used to sign new certificates (Why is it more secure to use intermediate CA certificates?) and the intermediate certificate will be distributed along with newly minted leaf certificates. In our demo, the server will present the intermediate certificate along with it's server (leaf) certificate allowing our client to validate the full chain using the root.

    2. Generate the configuration file required by the Step CA.

      See the Getting Started guide for an in depth explanation of the Step CA configuration file.

    
 $ 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'.

 $ 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 ...

    Now we've got an 'up and running' online CA!

  2. 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

  3. 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
 ...

    Notice that when you inspect srv.crt there are actually two certificates present. The first is your server (leaf) certificate and the second is the intermediate certificate. When an intermediate CA is used to sign leaf certificates it is not enough for the server to only show it's leaf certificate because the client (which only has access to the root certificate) will not be able to validate the full chain.

  4. Run the simple server.

    
 $ go run srv.go &

  5. 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.

  6. 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 ca help xxx where xxx is the subcommand you are interested in. Ex: step help ca provisioners list.

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

  4. On your browser by running step ca help --http :8080 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.