Static Secrets: Key/Value Secret Engine

Vault can be used to store any secret in a secure manner. The secrets may be SSL certificates and keys for your organization's domain, credentials to connect to a corporate database server, etc. Storing such sensitive information in plaintext is not desirable. This guide demonstrates the use case of Vault for secret storage.

Personas

The end-to-end scenario described in this guide involves two personas:

devops with privileged permissions to write secrets
apps reads the secrets from Vault

Challenge

Consider the following situations:

Developers use a single admin account to access a third-party app (e.g. Splunk) and anyone who knows the user ID and password can log in as an admin
SSH keys to connect to remote machines are shared and stored as a plaintext
API keys to invoke external system APIs are stored as a plaintext
An app integrates with LDAP, and its configuration information is in a plaintext

Organizations often seek an uniform workflow to securely store this sensitive information.

Solution

Use Vault as centralized secret storage to secure any sensitive information. Vault encrypts these secrets using 256-bit AES in GCM mode with a randomly generated nonce prior to writing them to its persistent storage. The storage backend never sees the unencrypted value, so even if an attacker gained access to the raw storage, they wouldn't be able to read your secrets.

Prerequisites

To perform the tasks described in this guide, you need to have a Vault environment. Refer to the Getting Started guide to install Vault. Make sure that your Vault server has been initialized and unsealed.

NOTE: An interactive tutorial is also available if you do not have a Vault environment to perform the steps described in this guide.

Policy requirements

NOTE: For the purpose of this guide, you can use the root token to work with Vault. However, it is recommended that root tokens are only used for just enough initial setup or in emergencies. As a best practice, use tokens with appropriate set of policies based on your role in the organization.

To perform all tasks demonstrated in this guide, your policy must include the following permissions:

# Enable key/value secret engine at the kv-v1 path
path "sys/mounts/kv-v1" {
  capabilities = [ "update" ]
}

# To list the available secret engines
path "sys/mounts" {
  capabilities = [ "read" ]
}

# Write and manage secrets in key/value secret engine
path "kv-v1/*" {
  capabilities = [ "create", "read", "update", "delete", "list" ]
}

# Create policies to permit apps to read secrets
path "sys/policies/acl/*" {
  capabilities = [ "create", "read", "update", "delete", "list" ]
}

# Create tokens for verification & test
path "auth/token/create" {
  capabilities = [ "create", "update", "sudo" ]
}

If you are not familiar with policies, complete the policies guide.

Steps

This guide demonstrates the basic steps to store secrets using Vault. The scenario here is to store the following secrets:

API key (Google API)
Root certificate of a production database (MySQL)

To store your API key within the configured physical storage for Vault, use the key/value secret engine.

The Key/Value secret engine passes any operation through to the configured storage backend for Vault. For example, if your Vault server is configured with Consul as its storage backend, a "read" operation turns into a read from Consul at the same path.

You will perform the following:

Enable KV Secret Engine
Store the Google API key
Store the root certificate for MySQL
Generate a token for apps
Retrieve the secrets

Personas Introduction

Step 1: Enable KV Secret Engine

Currently, when you start the Vault server in dev mode, it automatically enables v2 of the KV secret engine at secret/.

This guide focuses on key/value secret engine v1. The Versioned Key/Value Secret Engin guide highlights features that are specific to the key/value secret engine v2.

CLI command / API call using cURL / Web UI

CLI command

Execute the following command to check the KV secret engine version:

$ vault secrets list -detailed

Under the Options, the version number is indicated.

Path          Type         Accessor           ...   Options           Description
----          ----         --------                 -------           -----------
cubbyhole/    cubbyhole    cubbyhole_9d52aeac ...   map[]             per-token private secret storage
identity/     identity     identity_acea5ba9  ...   map[]             identity store
secret/       kv           kv_2226b7d3        ...   map[version:2]    key/value secret storage
...

Execute the following command to enable the key/value secret engine v1 at kv-v1/:

$ vault secrets enable -path="kv-v1" -version=1 kv

API call using cURL

To check the KV secret engine version, use the sys/mounts endpoint:

$ curl --header "X-Vault-Token: <TOKEN>" \
       <VAULT_ADDRESS>/v1/sys/mounts

Where <TOKEN> is your valid token, and <VAULT_ADDRESS> is where your vault server is running.

Example:

$ curl --header "X-Vault-Token: ..." \
       http://127.0.0.1:8200/v1/sys/mounts | jq
...
  "secret/": {
    "accessor": "kv_f05b8b9c",
    "config": {
      "default_lease_ttl": 0,
      "force_no_cache": false,
      "max_lease_ttl": 0,
      "plugin_name": ""
    },
    "description": "key/value secret storage",
    "local": false,
    "options": {
      "version": "2"
    },
    "seal_wrap": false,
    "type": "kv"
  },
...

NOTE: This example uses jq tool to format the JSON output for readability.

Execute the sys/mounts endpoint to enable the key/value secret engine v1 at kv-v1/:

# Specify the secret engine type and its version in the API request payload
$ tee payload.json <<EOF
{
  "type": "kv",
  "options": {
    "version": "1"
  }
}
EOF

$ curl --header "X-Vault-Token: ..." \
       --request POST \
       --data @payload.json \
       https://127.0.0.1:8200/v1/sys/mounts/kv-v1

Web UI

Open a web browser and launch the Vault UI (e.g. http://127.0.0.1:8200/ui) and then login. If the key/value v2 is enabled at secret, the UI indicates with v2 tag.
Select Enable new engine and click the KV radio button.
Click Next.
Enter kv-v1 in the Path field, and select 1 from the Version drop-down list.
Click Enable Engine.

Step 2: Store the Google API key

Everything after the kv-v1 path is a key-value pair to write to the secret engine. You can specify multiple values. If the value has a space, you need to surround it with quotes. Having keys with spaces is permitted, but strongly discouraged because it can lead to unexpected client-side behavior.

Let's assume that the path convention in your organization is kv-v1/<OWNER>/apikey/<APP> for API keys. To store the Google API key used by the engineering team, the path would be kv-v1/eng/apikey/Google. If you have an API key for New Relic owned by the DevOps team, the path would look like kv-v1/devops/apikey/New_Relic.

CLI command / API call using cURL / Web UI

CLI command

To set key/value secrets:

$ vault kv put kv-v1/<PATH> <KEY>=VALUE>

The <PATH> can be anything you want it to be, and your organization should decide on the naming convention that makes most sense.

Example:

$ vault kv put kv-v1/eng/apikey/Google key=AAaaBBccDDeeOTXzSMT1234BB_Z8JzG7JkSVxI
Success! Data written to: kv-v1/eng/apikey/Google

The secret key is "key" and its value is "AAaaBBccDDeeOTXzSMT1234BB_Z8JzG7JkSVxI" in this example.

Execute the following command to read back the secrets:

$ vault kv get kv-v1/eng/apikey/Google
=== Data ===
Key    Value
---    -----
key    AAaaBBccDDeeOTXzSMT1234BB_Z8JzG7JkSVxI

API call using cURL

Use kv-v1/<PATH> endpoint to set secrets:

$ curl --header "X-Vault-Token: <TOKEN>" \
       --request POST \
       --data @payload.json \
       <VAULT_ADDRESS>/v1/kv-v1/<PATH>

Where <TOKEN> is your valid token, and kv-v1/<PATH> is the path to your secrets. The payload.json contains the parameters to invoke the endpoint.

Example:

# Create the API request payload
$ tee payload.json <<EOF
{
  "key": "AAaaBBccDDeeOTXzSMT1234BB_Z8JzG7JkSVxI"
}
EOF

$ curl --header "X-Vault-Token: ..." \
       --request POST \
       --data @payload.json \
       http://127.0.0.1:8200/v1/kv-v1/eng/apikey/Google

The secret key is "key" and its value is "AAaaBBccDDeeOTXzSMT1234BB_Z8JzG7JkSVxI" in this example.

Read back the secret.

$ curl --header "X-Vault-Token: ..." \
       http://127.0.0.1:8200/v1/kv-v1/eng/apikey/Google | jq
{
   "request_id": "e4091d6a-759b-e629-afc5-1d9d15f4fbae",
   "lease_id": "",
   "renewable": false,
   "lease_duration": 2764800,
   "data": {
     "key": "AAaaBBccDDeeOTXzSMT1234BB_Z8JzG7JkSVxI"
   },
   "wrap_info": null,
   "warnings": null,
   "auth": null
}

Web UI

In the Web UI, select kv-v1 and then Create secret.
Enter eng/apikey/Google in the Path for this secret field, key in the key field, and some value in the key value field.
Click Save.
Clicking on the sensitive information toggle let you show or hide the secret value.

Step 3: Store the root certificate for MySQL

For the purpose of this guide, generate a mock certificate using OpenSSL.

$ openssl req -x509 -sha256 -nodes -newkey rsa:2048 -keyout selfsigned.key -out cert.pem

The generated cert.pem file will look something like this:

NOTE: If you don't have OpenSSL, copy the above certificate and save it as cert.pem.

CLI command / API call using cURL / Web UI

CLI command

The command is basically the same as the Google API key example. The path convention for certificates is kv-v1/<ENVIRONMENT>/cert/<SYSTEM>. To store the root certificate for production MySQL, the path becomes kv-v1/prod/cert/mysql.

$ vault kv put kv-v1/prod/cert/mysql cert=@cert.pem

This example reads the root certificate from a PEM file from the disk, and store it under the kv-v1/prod/cert/mysql path.

NOTE: Any value that begins with @ indicates a file name. Data will be loaded from this file.

API call using cURL

To perform the same task using the Vault API, pass the certificate in the request payload.

# Create the API request payload
$ tee payload-cert.json <<EOF
{
  "cert": "-----BEGIN CERTIFICATE-----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\n-----END CERTIFICATE-----\n"
}
EOF

$ curl --header "X-Vault-Token: ..." \
       --request POST \
       --data @payload-cert.json \
       http://127.0.0.1:8200/v1/kv-v1/prod/cert/mysql

Web UI

In the Web UI, select kv-v1 under Secrets Engines list and then Create secret.
Enter prod/cert/mysql in the Path for secret field, and cert in the key name field. Paste in the cert.pem contents.
Click Save.

Step 4: Generate a token for apps

To read the secrets, apps persona needs "read" ability on those secret engine paths. In this scenario, the apps policy must include the following:

Example: apps-policy.hcl

# Read-only permit
path "kv-v1/eng/apikey/Google" {
  capabilities = [ "read" ]
}

# Read-only permit
path "kv-v1/prod/cert/mysql" {
  capabilities = [ "read" ]
}

CLI command / API call using cURL / Web UI

CLI command

First create apps policy, and generate a token so that you can authenticate as an apps persona, and read secrets.

# Create "apps" policy
$ vault policy write apps apps-policy.hcl
Policy 'apps' written.

# Create a new token with app policy
$ vault token create -policy="apps"
Key             Value
---             -----
token           e4bdf7dc-cbbf-1bb1-c06c-6a4f9a826cf2
token_accessor  54700b7e--data828-a6c4-6141-96e71e002bd7
token_duration  768h0m0s
token_renewable true
token_policies  [apps default]

Now apps can use this token to read the secrets.

API call using cURL

First create an apps policy, and generate a token so that you can authenticate as an app persona.

Example:

# Payload to pass in the API call
$ tee payload-policy.json <<EOF
{
  "policy":  "# Read-only permit\npath \"kv-v1/eng/apikey/Google\" {\n  capabilities = [ \"read\" ]\n}\n\n# Read-only permit\npath \"kv-v1/prod/cert/mysql\" {\n  capabilities = [ \"read\" ]\n}"
}
EOF

# Create "apps" policy
$ curl --header "X-Vault-Token: ..." \
       --request PUT \
       --data @payload-policy.json \
       http://127.0.0.1:8200/v1/sys/policies/acl/apps

# Generate a new token with apps policy
$ curl --header "X-Vault-Token: ..." \
       --request POST \
       --data '{"policies": ["apps"]}' \
       http://127.0.0.1:8200/v1/auth/token/create | jq
{
 "request_id": "e1737bc8-7e51-3943-42a0-2dbd6cb40e3e",
 "lease_id": "",
 "renewable": false,
 "lease_duration": 0,
 "data": null,
 "wrap_info": null,
 "warnings": null,
 "auth": {
   "client_token": "1c97b03a-6098-31cf-9d8b-b404e52dcb4a",
   "accessor": "b10a3eb7-15fe-1924-600e-403cfda34c28",
   "policies": [
     "apps",
     "default"
   ],
   "metadata": null,
   "lease_duration": 2764800,
   "renewable": true,
   "entity_id": ""
 }
}

Now apps can use this token to read the secrets.

Web UI

Open a web browser and click the Policies tab, and then select Create ACL policy.
Toggle the Upload file sliding switch, and click Choose a file to select your apps-policy.hcl file you authored. Set the Name to apps.
Click Create Policy to complete.
Click the Vault CLI shell icon (>_) to open a command shell. Execute the following command to create a new token: vault write auth/token/create policies=apps

Now apps can use this token to read the secrets. Create token

NOTE: For the purposes of this guide, you created a policy for the apps persona, and generated a token for it. However, in the real world, you may have a dedicated policy author, or admin to write policies. Also, the consumer of the API key may be different from the consumer of the root certificate. Then each persona would have a policy based on what it needs to access.

Personas Introduction

Step 5: Retrieve the secrets

Using the token from Step 4, read the Google API key and the root certificate for MySQL.

CLI command / API call using cURL

CLI command

The command to read a secret is:

$ vault kv get kv-v1/<PATH>

Example:

# Authenticate with Vault using the generated token first
$ vault login e4bdf7dc-cbbf-1bb1-c06c-6a4f9a826cf2
Successfully authenticated! You are now logged in.
token: e4bdf7dc-cbbf-1bb1-c06c-6a4f9a826cf2
token_duration: 2764277
token_policies: [apps default]

# Read the API key
$ vault kv get kv-v1/eng/apikey/Google
Key                 Value
---                 -----
refresh_interval    768h0m0s
key                 AAaaBBccDDeeOTXzSMT1234BB_Z8JzG7JkSVxI

To return the key's value and nothing else, pass -field=key as an argument.

$ vault kv get -field=key kv-v1/eng/apikey/Google
AAaaBBccDDeeOTXzSMT1234BB_Z8JzG7JkSVxI

Root certificate example:

The command is basically the same:

$ vault kv get -field=cert kv-v1/prod/cert/mysql
-----BEGIN RSA PRIVATE KEY-----
MIIEowIBAAKCAQEA6E2Uq0XqreZISgVMUu9pnoMsq+OoK1PI54rsA9vtDE6wiRk0GWhf5vD4DGf1
...

API call using cURL

Read the Google API key.

$ curl --header "X-Vault-Token: 1c97b03a-6098-31cf-9d8b-b404e52dcb4a" \
       --request GET \
       http://127.0.0.1:8200/v1/kv-v1/eng/apikey/Google | jq
{
  "request_id": "5a2005ac-1149-2275-cab3-76cee71bf524",
  "lease_id": "",
  "renewable": false,
  "lease_duration": 2764800,
  "data": {
    "key": "AAaaBBccDDeeOTXzSMT1234BB_Z8JzG7JkSVxI"
  },
  "wrap_info": null,
  "warnings": null,
  "auth": null
}

Retrieve the key value using jq:

$ curl --header "X-Vault-Token: 1c97b03a-6098-31cf-9d8b-b404e52dcb4a" \
       --request GET \
       http://127.0.0.1:8200/v1/kv-v1/eng/apikey/Google | jq ".data.key"

Root certificate example:

$ curl --header "X-Vault-Token: 1c97b03a-6098-31cf-9d8b-b404e52dcb4a" \
       --request GET \
       http://127.0.0.1:8200/v1/kv-v1/prod/cert/mysql | jq ".data.cert"

Additional Discussion

Q: How do I enter my secrets without exposing the secret in my shell's history?

As a precaution, you may wish to avoid passing your secret as a part of the CLI command so that the secret won't appear in the history file. Here are a few techniques you can use.

Option 1: Use a dash "-"

An easy technique is to use a dash "-" and then press Enter. This allows you to enter the secret on a new line. After entering the secret, press Ctrl+d to end the pipe which will write the secret to the Vault.

$ vault kv put kv-v1/eng/apikey/Google key=-

AAaaBBccDDeeOTXzSMT1234BB_Z8JzG7JkSVxI
<Ctrl+d>

Option 2: Read the secret from a file

Using the Google API key example, you can create a file containing the key (apikey.txt):

{
  "key": "AAaaBBccDDeeOTXzSMT1234BB_Z8JzG7JkSVxI"
}

The CLI command would look like:

$ vault kv put kv-v1/eng/apikey/Google @apikey.txt

Option 3: Disable all vault command history

Sometimes, you may not even want the vault command itself to appear in history at all. Option 1 and Option 2 prevent the secret from appearing in your shell history. The vault command itself (vault kv put kv-v1/eng/apikey/Google) will still appear in your history.

You can configure your shell to avoid logging any vault commands to your history.

In bash:

$ export HISTIGNORE="&:vault*"

NOTE: This prevents vault commands from appearing when using the Up arrow or when searching command history with <Ctrl-r>.

Q: How do I save multiple values at once?

The two examples introduced in this guide only had a single key/value pair. You can pass multiple values in a single command.

$ vault kv put kv-v1/dev/config/mongodb url=foo.example.com:35533 db_name=users \
 username=admin password=passw0rd

Or, read several secrets from a file:

$ tee mongodb.json <<EOF
{
    "url": "foo.example.com:35533",
    "db_name": "users",
    "username": "admin",
    "password": "pa$$w0rd"
}
EOF

$ vault kv put kv-v1/dev/config/mongodb @mongodb.json

Help and Reference

Key/Value Secret Engine
Key/Value Secret Engine API
Client libraries for Vault API for commonly used languages

Sentinel

Tokens

Static Secrets: Key/Value Secret Engine

Versioned Key/Value Secret Engine

Cubbyhole Response Wrapping

Secrets as a Service: Dynamic Secrets

Database Static Roles and Credential Rotation

Encryption as a Service: Transit Secrets Engine

Transit Secrets Re-wrapping

Java Application Demo

Direct Application Integration

AppRole Pull Authentication

Secure Introduction of Vault Clients

Vault Agent with AWS

Vault Agent with Kubernetes

Vault Agent Caching

AppRole With Terraform & Chef

Building Plugin Backends

Tokens

Static Secrets: Key/Value Secret Engine

Versioned Key/Value Secret Engine

Cubbyhole Response Wrapping

Secrets as a Service: Dynamic Secrets

Database Static Roles and Credential Rotation

Encryption as a Service: Transit Secrets Engine

Transit Secrets Re-wrapping

Java Application Demo

Direct Application Integration

AppRole Pull Authentication

Secure Introduction of Vault Clients

Vault Agent with AWS

Vault Agent with Kubernetes

Vault Agent Caching

AppRole With Terraform & Chef

Building Plugin Backends

Static Secrets: Key/Value Secret Engine

»Personas

»Challenge

»Solution

»Prerequisites

»Policy requirements

»Steps

»Step 1: Enable KV Secret Engine

»CLI command

»API call using cURL

»Web UI

»Step 2: Store the Google API key

»CLI command

»API call using cURL

»Web UI

»Step 3: Store the root certificate for MySQL

»CLI command

»API call using cURL

»Web UI

»Step 4: Generate a token for apps

»CLI command

»API call using cURL

»Web UI

»Step 5: Retrieve the secrets

»CLI command

»Root certificate example:

»API call using cURL

»Root certificate example:

»Additional Discussion

»Q: How do I enter my secrets without exposing the secret in my shell's history?

»Option 1: Use a dash "-"

»Option 2: Read the secret from a file

»Option 3: Disable all vault command history

»Q: How do I save multiple values at once?

»Help and Reference

Personas

Challenge

Solution

Prerequisites

Policy requirements

Steps

Step 1: Enable KV Secret Engine

CLI command

API call using cURL

Web UI

Step 2: Store the Google API key

CLI command

API call using cURL

Web UI

Step 3: Store the root certificate for MySQL

CLI command

API call using cURL

Web UI

Step 4: Generate a token for apps

CLI command

API call using cURL

Web UI

Step 5: Retrieve the secrets

CLI command

Root certificate example:

API call using cURL

Root certificate example:

Additional Discussion

Q: How do I enter my secrets without exposing the secret in my shell's history?

Option 1: Use a dash "-"

Option 2: Read the secret from a file

Option 3: Disable all vault command history

Q: How do I save multiple values at once?

Help and Reference