# Create Security Certificates

To secure your CockroachDB cluster's inter-node and client-node communication, you need to provide a Certificate Authority (CA) certificate that has been used to sign keys and certificates (SSLs) for:

- Nodes
- Clients
- Admin UI (optional)

To create these certificates and keys, use the `cockroach cert` commands with the appropriate subcommands and flags, use `openssl` commands, or use a custom CA (for example, a public CA or your organizational CA).

Tip:
For details about when and how to change security certificates without restarting nodes, see Rotate Security Certificates.

## How security certificates work

1. Using the `cockroach cert` command, you create a CA certificate and key and then node and client certificates that are signed by the CA certificate. Since you need access to a copy of the CA certificate and key to create node and client certs, it's best to create everything in one place.

2. You then upload the appropriate node certificate and key and the CA certificate to each node, and you upload the appropriate client certificate and key and the CA certificate to each client.

3. When nodes establish contact to each other, and when clients establish contact to nodes, they use the CA certificate to verify each other's identity.

## Subcommands

Subcommand | Usage
--- | ---
`create-ca` | Create the self-signed certificate authority (CA), which you'll use to create and authenticate certificates for your entire cluster.
`create-node` | Create a certificate and key for a specific node in the cluster. You specify all addresses at which the node can be reached and pass appropriate flags.
`create-client` | Create a certificate and key for a specific user accessing the cluster from a client. You specify the username of the user who will use the certificate and pass appropriate flags.
`list` | List certificates and keys found in the certificate directory.

## Certificate directory

When using `cockroach cert` to create node and client certificates, you will need access to a local copy of the CA certificate and key. It is therefore recommended to create all certificates and keys in one place and then distribute node and client certificates and keys appropriately. For the CA key, be sure to store it somewhere safe and keep a backup; if you lose it, you will not be able to add new nodes or clients to your cluster. For a walkthrough of this process, see Manual Deployment.

## Required keys and certificates

The `create-*` subcommands generate the CA certificate and all node and client certificates and keys in a single directory specified by the `--certs-dir` flag, with the files named as follows:

### Node key and certificates

File name pattern | File usage
--- | ---
`ca.crt` | CA certificate.
`node.crt` | Server certificate. `node.crt` must be signed by `ca.crt` and must have `CN=node` and the list of IP addresses and DNS names listed in `Subject Alternative Name` field.
`node.key` | Key for server certificate.

### Client key and certificates

File name pattern | File usage
--- | ---
`ca.crt` | CA certificate.
`client.<user>.crt` | Client certificate for `<user>` (e.g., `client.root.crt` for user `root`). Must be signed by `ca.crt`. Also, `client.<username>.crt` must have `CN=<user>` (for example, `CN=marc` for `client.marc.crt`)
`client.<user>.key` | Key for the client certificate.

Optionally, if you have a certificate issued by a public CA to securely access the Admin UI, you need to place the certificate and key (`ui.crt` and `ui.key` respectively) in the directory specified by the `--certs-dir` flag. For more information, refer to Use a UI certificate and key to access the Admin UI.

Note the following:

- By default, the `node.crt` is multi-functional, as in the same certificate is used for both incoming connections (from SQL and Admin UI clients, and from other CockroachDB nodes) and for outgoing connections to other CockroachDB nodes. To make this possible, the `node.crt` created using the `cockroach cert` command has `CN=node` and the list of IP addresses and DNS names listed in `Subject Alternative Name` field.

- The CA key is never loaded automatically by `cockroach` commands, so it should be created in a separate directory, identified by the `--ca-key` flag.

- Keys (files ending in `.key`) must not have group or world permissions (maximum permissions are 0700, or `rwx------`). This check can be disabled by setting the environment variable `COCKROACH_SKIP_KEY_PERMISSION_CHECK=true`.

## Synopsis

    # Create the CA certificate and key:
    $ cockroach cert create-ca \
     --certs-dir=[path-to-certs-directory] \
     --ca-key=[path-to-ca-key]

    # Create a node certificate and key:
    $ cockroach cert create-node \
     [node-hostname] \
     [node-other-hostname] \
     [node-yet-another-hostname] \
     --certs-dir=[path-to-certs-directory] \
     --ca-key=[path-to-ca-key]

    # Create a client certificate and key:
    $ cockroach cert create-client \
     [username] \
     --certs-dir=[path-to-certs-directory] \
     --ca-key=[path-to-ca-key]

    # List certificates and keys:
    $ cockroach cert list \
     --certs-dir=[path-to-certs-directory]

    # View help:
    $ cockroach cert --help
    $ cockroach cert create-ca --help
    $ cockroach cert create-node --help
    $ cockroach cert create-client --help
    $ cockroach cert list --help

## Flags

The `cert` command and subcommands support the following general-use and logging flags.

### General

Flag | Description
--- | ---
`--certs-dir` | The path to the certificate directory containing all certificates and keys needed by `cockroach` commands. This flag is used by all subcommands. Default: `${HOME}/.cockroach-certs/`
`--ca-key` | The path to the private key protecting the CA certificate. This flag is required for all `create-*` subcommands. When used with `create-ca` in particular, it defines where to create the CA key; the specified directory must exist. Env Variable: `COCKROACH_CA_KEY`
`--allow-ca-key-reuse` | When running the `create-ca` subcommand, pass this flag to re-use an existing CA key identified by `--ca-key`. Otherwise, a new CA key will be generated. This flag is used only by the `create-ca` subcommand. It helps avoid accidentally re-using an existing CA key.
`--overwrite` | When running `create-*` subcommands, pass this flag to allow existing files in the certificate directory (`--certs-dir`) to be overwritten. This flag helps avoid accidentally overwriting sensitive certificates and keys.
`--lifetime` | The lifetime of the certificate, in hours, minutes, and seconds. Certificates are valid from the time they are created through the duration specified in `--lifetime`. Default: `87840h0m0s` (10 years)
`--key-size` | The size of the CA, node, or client key, in bits. Default: `2048`

### Logging

By default, the `cert` command logs errors to `stderr`.

If you need to troubleshoot this command's behavior, you can change its logging behavior.

## Examples

### Create the CA certificate and key pair

1. Create two directories:

       $ mkdir certs

       $ mkdir my-safe-directory

   - `certs`: You'll generate your CA certificate and all node and client certificates and keys in this directory and then upload some of the files to your nodes.
   - `my-safe-directory`: You'll generate your CA key in this directory and then reference the key when generating node and client certificates. After that, you'll keep the key safe and secret; you will not upload it to your nodes.

2. Generate the CA certificate and key:

       $ cockroach cert create-ca \
       --certs-dir=certs \
       --ca-key=my-safe-directory/ca.key

       $ ls -l certs

       total 8
       -rw-r--r--  1 maxroach  maxroach  1.1K Jul 10 14:12 ca.crt

### Create the certificate and key pairs for nodes

1. Generate the certificate and key for the first node:

       $ cockroach cert create-node \
       node1.example.com \
       node1.another-example.com \
       --certs-dir=certs \
       --ca-key=my-safe-directory/ca.key

       $ ls -l certs

       total 24
       -rw-r--r--  1 maxroach  maxroach  1.1K Jul 10 14:12 ca.crt
       -rw-r--r--  1 maxroach  maxroach  1.2K Jul 10 14:16 node.crt
       -rw-------  1 maxroach  maxroach  1.6K Jul 10 14:16 node.key

2. Upload certificates to the first node:

       # Create the certs directory:
       $ ssh <username>@<node1 address> "mkdir certs"

       # Upload the CA certificate and node certificate and key:
       $ scp certs/ca.crt \
       certs/node.crt \
       certs/node.key \
       <username>@<node1 address>:~/certs

3. Delete the local copy of the first node's certificate and key:

       $ rm certs/node.crt certs/node.key

   Note:
   This is necessary because the certificates and keys for additional nodes will also be named `node.crt` and `node.key` As an alternative to deleting these files, you can run the next `cockroach cert create-node` commands with the `--overwrite` flag.

4. Create the certificate and key for the second node:

       $ cockroach cert create-node \
       node2.example.com \
       node2.another-example.com \
       --certs-dir=certs \
       --ca-key=my-safe-directory/ca.key

       $ ls -l certs

       total 24
       -rw-r--r--  1 maxroach  maxroach  1.1K Jul 10 14:12 ca.crt
       -rw-r--r--  1 maxroach  maxroach  1.2K Jul 10 14:17 node.crt
       -rw-------  1 maxroach  maxroach  1.6K Jul 10 14:17 node.key

5. Upload certificates to the second node:

       # Create the certs directory:
       $ ssh <username>@<node2 address> "mkdir certs"

       # Upload the CA certificate and node certificate and key:
       $ scp certs/ca.crt \
       certs/node.crt \
       certs/node.key \
       <username>@<node2 address>:~/certs

6. Repeat steps 3 - 5 for each additional node.

### Create the certificate and key pair for a client

    $ cockroach cert create-client \
    maxroach \
    --certs-dir=certs \
    --ca-key=my-safe-directory/ca.key

    $ ls -l certs

    total 40
    -rw-r--r--  1 maxroach  maxroach  1.1K Jul 10 14:12 ca.crt
    -rw-r--r--  1 maxroach  maxroach  1.1K Jul 10 14:13 client.maxroach.crt
    -rw-------  1 maxroach  maxroach  1.6K Jul 10 14:13 client.maxroach.key
    -rw-r--r--  1 maxroach  maxroach  1.2K Jul 10 14:17 node.crt
    -rw-------  1 maxroach  maxroach  1.6K Jul 10 14:17 node.key

### List certificates and keys

    $ cockroach cert list \
    --certs-dir=certs

    Certificate directory: certs
    +-----------------------+---------------------+---------------------+------------+--------------------------------------------------------+-------+
    |         Usage         |  Certificate File   |      Key File       |  Expires   |                         Notes                          | Error |
    +-----------------------+---------------------+---------------------+------------+--------------------------------------------------------+-------+
    | Certificate Authority | ca.crt              |                     | 2027/07/18 | num certs: 1                                           |       |
    | Node                  | node.crt            | node.key            | 2022/07/14 | addresses: node2.example.com,node2.another-example.com |       |
    | Client                | client.maxroach.crt | client.maxroach.key | 2022/07/14 | user: maxroach                                         |       |
    +-----------------------+---------------------+---------------------+------------+--------------------------------------------------------+-------+
    (3 rows)

## See also

- Client Connection Parameters
- Rotate Security Certificates
- Manual Deployment
- Orchestrated Deployment
- Local Deployment
- Other Cockroach Commands