Create Security Certificates using OpenSSL

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
  • DB Console (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).

Subcommands

Subcommand Usage
openssl genrsa Create an RSA private key.
openssl req Create CA certificate and CSRs (certificate signing requests).
openssl ca Create node and client certificates using the CSRs.

Configuration files

To use openssl req and openssl ca subcommands, you need the following configuration files:

File name pattern File usage
ca.cnf CA configuration file
node.cnf Server configuration file
client.cnf Client configuration file

Certificate directory

To create node and client certificates using the OpenSSL commands, you need access to a local copy of the CA certificate and key. We recommend creating all certificates (node, client, and CA certificates), and node and client keys in one place and then distributing them appropriately. Store the CA key somewhere safe and keep a backup; if you lose it, you will not be able to add new nodes or clients to your cluster.

Required keys and certificates

Use the openssl genrsa and openssl req subcommands to create all certificates, and node and client keys in a single directory, with the files named as follows:

Node key and certificates

File name pattern File usage
ca.crt CA certificate
node.crt Server certificate
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> (for example: client.root.crt for user root).
client.<user>.key Key for the client certificate.

Note the following:

  • The CA key should not be uploaded to the nodes and clients, so it should be created in a separate directory.

  • Keys (files ending in .key) must meet the permission requirements check on macOS, Linux, and other UNIX-like systems.

Examples

Step 1. Create the CA key and certificate pair

  1. Create two directories:

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    $ mkdir certs my-safe-directory
    
    • certs: Create your CA certificate and all node and client certificates and keys in this directory and then upload the relevant files to the nodes and clients.
    • my-safe-directory: Create your CA key in this directory and then reference the key when generating node and client certificates. After that, keep the key safe and secret; do not upload it to your nodes or clients.
  2. Create the ca.cnf file and copy the following configuration into it.

    You can set the CA certificate expiration period using the default_days parameter. We recommend using the CockroachDB default value of the CA certificate expiration period, which is 365 days.

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    # OpenSSL CA configuration file
    [ ca ]
    default_ca = CA_default
    
    [ CA_default ]
    default_days = 365
    database = index.txt
    serial = serial.txt
    default_md = sha256
    copy_extensions = copy
    unique_subject = no
    
    # Used to create the CA certificate.
    [ req ]
    prompt=no
    distinguished_name = distinguished_name
    x509_extensions = extensions
    
    [ distinguished_name ]
    organizationName = Cockroach
    commonName = Cockroach CA
    
    [ extensions ]
    keyUsage = critical,digitalSignature,nonRepudiation,keyEncipherment,keyCertSign
    basicConstraints = critical,CA:true,pathlen:1
    
    # Common policy for nodes and users.
    [ signing_policy ]
    organizationName = supplied
    commonName = optional
    
    # Used to sign node certificates.
    [ signing_node_req ]
    keyUsage = critical,digitalSignature,keyEncipherment
    extendedKeyUsage = serverAuth,clientAuth
    
    # Used to sign client certificates.
    [ signing_client_req ]
    keyUsage = critical,digitalSignature,keyEncipherment
    extendedKeyUsage = clientAuth
    
    Warning:

    The keyUsage and extendedkeyUsage parameters are vital for CockroachDB functions. You can modify or omit other parameters as per your preferred OpenSSL configuration and you can add additional usages, but do not omit keyUsage and extendedkeyUsage parameters or remove the listed usages.

  3. Create the CA key using the openssl genrsa command:

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    $ openssl genrsa -out my-safe-directory/ca.key 2048
    
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    $ chmod 400 my-safe-directory/ca.key
    
  4. Create the CA certificate using the openssl req command:

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    $ openssl req \
    -new \
    -x509 \
    -config ca.cnf \
    -key my-safe-directory/ca.key \
    -out certs/ca.crt \
    -days 365 \
    -batch
    
  5. Reset database and index files:

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    $ rm -f index.txt serial.txt
    
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    $ touch index.txt
    
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    $ echo '01' > serial.txt
    

Step 2. Create the certificate and key pairs for nodes

In the following steps, replace the placeholder text in the code with the actual username and node address.

  1. Create the node.cnf file for the first node and copy the following configuration into it:

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    # OpenSSL node configuration file
    [ req ]
    prompt=no
    distinguished_name = distinguished_name
    req_extensions = extensions
    
    [ distinguished_name ]
    organizationName = Cockroach
    
    [ extensions ]
    subjectAltName = critical,DNS:<node-hostname>,DNS:<node-domain>,IP:<IP Address>
    
    Warning:

    The subjectAltName parameter is vital for CockroachDB functions. You can modify or omit other parameters as per your preferred OpenSSL configuration, but do not omit the subjectAltName parameter.

  2. Create the key for the first node using the openssl genrsa command:

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    $ openssl genrsa -out certs/node.key 2048
    
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    $ chmod 400 certs/node.key
    
  3. Create the CSR for the first node using the openssl req command:

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    $ openssl req \
    -new \
    -config node.cnf \
    -key certs/node.key \
    -out node.csr \
    -batch
    
  4. Sign the node CSR to create the node certificate for the first node using the openssl ca command.

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    $ openssl ca \
    -config ca.cnf \
    -keyfile my-safe-directory/ca.key \
    -cert certs/ca.crt \
    -policy signing_policy \
    -extensions signing_node_req \
    -out certs/node.crt \
    -outdir certs/ \
    -in node.csr \
    -batch
    
  5. Verify the values in the Subject Alternative Name field in the certificate:

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    $ openssl x509 -in certs/node.crt -text | grep "X509v3 Subject Alternative Name" -A 1
    

    Sample output:

    X509v3 Subject Alternative Name: critical
                DNS:localhost, DNS:node.example.io, IP Address:127.0.0.1
    

Step 3. Create the certificate and key pair for the first user

In the following steps, replace the placeholder text in the code with the actual username.

  1. Create the client.cnf file for the first user and copy the following configuration into it:

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    [ req ]
    prompt=no
    distinguished_name = distinguished_name
    req_extensions = extensions
    
    [ distinguished_name ]
    organizationName = Cockroach
    commonName = <username_1>
    
    [ extensions ]
    subjectAltName = DNS:root
    
    Warning:

    The commonName and subjectAltName parameters are vital for CockroachDB functions. You can modify or omit other parameters as per your preferred OpenSSL configuration, but do not omit the commonName parameter or modify the subjectAltName parameter.

  2. Create the key for the first client using the openssl genrsa command:

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    $ openssl genrsa -out certs/client.<username_1>.key 2048
    
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    $ chmod 400 certs/client.<username_1>.key
    
  3. Create the CSR for the first client using the openssl req command:

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    $ openssl req \
    -new \
    -config client.cnf \
    -key certs/client.<username_1>.key \
    -out client.<username_1>.csr \
    -batch
    
  4. Sign the client CSR to create the client certificate for the first client using the openssl ca command.

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    $ openssl ca \
    -config ca.cnf \
    -keyfile my-safe-directory/ca.key \
    -cert certs/ca.crt \
    -policy signing_policy \
    -extensions signing_client_req \
    -out certs/client.<username_1>.crt \
    -outdir certs/ \
    -in client.<username_1>.csr \
    -batch
    
  5. Verify the values in the CN field in the certificate:

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    $ openssl x509 -in certs/client.<username_1>.crt -text | grep CN=
    

    Sample Output:

    Issuer: O=Cockroach, CN=Cockroach CA
        Subject: O=Cockroach, CN=maxroach
    

Step 4. Start a local cluster and connect using a connection URL

  1. Start a single-node cluster:

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    $ cockroach start-single-node --certs-dir=certs --cert-principal-map=<node-domain>:node,<username_1>:root --background
    
  2. Connect to the cluster using a connection URL:

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    $ cockroach sql --url='postgres://<hostname>:26257/?sslmode=verify-full&sslrootcert=certs/ca.crt&sslcert=certs/client.<username_1>.crt&sslkey=certs/client.<username_1>.key&sslmode=verify-full'
    
  3. Create a new SQL user:

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    > create user <username_2>;
    
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    > \q
    

Step 5. Create the certificate and key pair for a client

In the following steps, replace the placeholder text in the code with the actual username.

  1. Edit the client.cnf file for the client and copy the following configuration into it:

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    [ req ]
    prompt=no
    distinguished_name = distinguished_name
    
    [ distinguished_name ]
    organizationName = Cockroach
    commonName = <username_2>
    
    Warning:

    The commonName parameter is vital for CockroachDB functions. You can modify or omit other parameters as per your preferred OpenSSL configuration, but do not omit the commonName parameter.

  2. Create the key for the first client using the openssl genrsa command:

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    $ openssl genrsa -out certs/client.<username_2>.key 2048
    
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    $ chmod 400 certs/client.<username_2>.key
    
  3. Create the CSR for the first client using the openssl req command:

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    $ openssl req \
    -new \
    -config client.cnf \
    -key certs/client.<username_2>.key \
    -out client.<username_2>.csr \
    -batch
    
  4. Sign the client CSR to create the client certificate for the first client using the openssl ca command.

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    $ openssl ca \
    -config ca.cnf \
    -keyfile my-safe-directory/ca.key \
    -cert certs/ca.crt \
    -policy signing_policy \
    -extensions signing_client_req \
    -out certs/client.<username_2>.crt \
    -outdir certs/ \
    -in client.<username_2>.csr \
    -batch
    
  5. Verify the values in the CN field in the certificate:

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    $ openssl x509 -in certs/client.<username_2>.crt -text | grep CN=
    

    Sample output:

    Issuer: O=Cockroach, CN=Cockroach CA
        Subject: O=Cockroach, CN=roach
    
  6. Connect to the SQL client using the client certificate:

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    $ cockroach sql --url='postgres://<username_2>@<hostname>:26257/?sslmode=verify-full&sslrootcert=certs/ca.crt&sslcert=certs/client.<username_2>.crt&sslkey=certs/client.<username_2>.key&sslmode=verify-full'
    

For each node in your deployment, repeat Step 2 and upload the CA certificate and node key and certificate to the node. For each client, repeat Step 5 and upload the CA certificate and client key and certificate to the client.

After you have uploaded all the keys and certificates to the corresponding nodes and clients, remove the .pem files in the certs directory. These files are unnecessary duplicates of the .crt files that CockroachDB requires.

See also

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