Now that we can use client certificates to authenticate with Vault, we can use that certificate in our browser (Chrome) in combination with Postman.

Step 1 - get the certificate in the browser

The easiest way is to convert the key and certificate into a p12 container file. Openssl supports this out of the box:

$ openssl pkcs12 -export -clcerts -in cert.pem -inkey key.pem -out vaultcert.p12
Enter pass phrase for key.pem:
Enter Export Password:
Verifying - Enter Export Password:

I obviously used the same password to encrypt the p12 container ;-) Now get the vaultcert.p12 file to the machine with your browser (if it’s not the same) and import it. Here and here are tutorials describing the steps, so I wont repeat.

When you browse to your Vault setup, you should get a prompt for a client certificate, and your freshly imported Vault certificate should now be listed.

Step 2 - install Postman

I won’t go into too much detail - Postman gives you a flexible REST client. There are many other options here. Installation is so straight forward, I will leave it as an exercise to the reader…

Step 3 - communicate with Vault

First, we use the certificate to get a temporary token.

In the builder, set the request type to POST and the url to your Vault server’s certificat authentication API: When you click “send”, you should get a popup asking you to select a certificate similar to this one. Select the correct certificate from the list. You should now get a Body containing (among other) a valid Vault token (client_token):

    "lease_id": "",
    "renewable": false,
    "lease_duration": 0,
    "data": null,
    "wrap_info": null,
    "warnings": null,
    "auth": {
        "client_token": "40xxxxd8-xxxx-bfaf-xxxx-480bxxxx8615",
        "accessor": "0fxxxxea-xxxx-0253-xxxx-52fdxxxx36cf",
        "policies": [
        "metadata": {
            "authority_key_id": "",
            "cert_name": "",
            "common_name": "Your Name",
            "subject_key_id": ""
        "lease_duration": 3600,
        "renewable": true

Now we can use the token to do other things.

Look up the metadata of the Vault token:

  • switch the POST back to GET
  • enter this url:
  • add the Vault token in Headers (key name X-Vault-Token)

The result should tell you whether your token is sill valid (ttl) and what policies are attached to it.