Using the Key Management Interoperability Protocol (KMIP)¶

Version added: 5.0.7-6

Percona Server for MongoDB adds support for secure transfer of keys using the OASIS Key Management Interoperability Protocol (KMIP). The KMIP implementation was tested with the PyKMIP server and the HashiCorp Vault Enterprise KMIP Secrets Engine.

KMIP enables the communication between key management systems and the database server. KMIP provides the following benefits:

Streamlines encryption key management
Eliminates redundant key management processes
Reduces the mean time to resolve (MTTR) compromised encryption key incidents via key state polling

Version changes

The following table lists the changes in the KMIP implementation in Percona Server for MongoDB and the versions that introduced those changes:

Version	Description
5.0.8-7	Master key rotation.
5.0.9-8	Support for multiple KMIP servers for failover.
5.0.11-10	Changed handling of `kmipKeyIdentifier` option.
5.0.28-24	Key state polling.

Support for multiple KMIP servers¶

Starting with version 5.0.9-8, you can specify multiple KMIP servers for failover. On startup, Percona Server for MongoDB connects to the servers in the order listed and selects the one with which the connection is successful.

Optional key identifier¶

Starting with version 5.0.11-10, the kmipKeyIdentifier option is no longer mandatory. When left blank, the database server creates a key on the KMIP server and uses that for encryption. When you specify the identifier, the key with such an ID must exist on the key storage.

Note

Starting with version 5.0.17-14, the master key is stored in a raw-byte format. If you set up Percona Server for MongoDB 5.0.17-14 with data-at-rest encryption using KMIP and wish to downgrade to some previous version, this downgrade is not possible via binary replacement. Consider using the logical backup and restore via Percona Backup for MongoDB for this purpose.

Key rotation¶

Starting with version 5.0.8-7, the support for master key rotation is added. This enables users to comply with data security regulations when using KMIP.

Key state polling¶

When a Percona Server for MongoDB node generates a new master encryption key, it registers the key on the KMIP server with the Pre-Active state. Starting with version 5.0.28-24, Percona Server for MongoDB automatically activates the master encryption key and periodically checks (polls) its state. If a master encryption key for a node is not in the Active state, the node reports an error and shuts down. This process helps security engineers identify the nodes that require out-of-schedule master key rotation.

Key state polling es enabled by default and is regulated by these configuration file options: kmip.activateKeys and kmip.keyStatePollingSeconds.

The following diagram illustrates the master key lifecycle with key state polling:

The master key state polling functionality is particularly useful in cluster deployments with hundreds of nodes. If some master keys are compromised, security engineers change their state from Active so that the nodes encrypted with these keys identify themselves. This approach allows the security engineers to rotate master keys only on the affected nodes instead of the entire cluster, thus reducing the mean time to resolve (MTTR) compromised encryption key incidents.

KMIP parameters¶

Configuration file	security.kmip.serverName
Command line	`kmipServerName`
Type	string
Description	The hostname or IP address of the KMIP server. As of version 4.2.21-21, multiple KMIP servers are supported as the comma-separated list, e.g. `kmip1.example.com,kmip2.example.com`

Configuration file	security.kmip.port
Command line	`kmipPort`
Type	number
Description	The port used to communicate with the KMIP server. When undefined, the default port `5696` is used

Configuration file	security.kmip.serverCAFile
Command line	`kmipServerCAFile`
Type	string
Description	The path to the certificate of the root authority that issued the certificate for the KMIP server. Required only if the root certificate is not trusted by default on the machine the database server works on.

Configuration file	security.kmip.clientCertificateFile
Command line	`kmipClientCertificateFile`
Type	string
Description	The path to the PEM file with the KMIP client private key and the certificate chain. The database server uses this PEM file to authenticate the KMIP server

Configuration file	security.kmip.keyIdentifier
Command line	`kmipKeyIdentifier`
Type	string
Description	Optional starting with version 5.0.11-10. The identifier of the KMIP key. If not specified, the database server creates a key on the KMIP server and saves its identifier internally for future use. When you specify the identifier, the key with such an ID must exist on the key storage. You can only use this setting for the first time you enable encryption.

Configuration file	security.kmip.rotateMasterKey
Command line	`kmipRotateMasterKey`
Type	boolean
Description	Controls master keys rotation. When enabled, generates the new master key version and re-encrypts the keystore. Available as of version 5.0.8-7.

Configuration file	security.kmip.clientCertificatePassword
Command line	`kmipClientCertificatePassword`
Type	string
Description	The password for the KMIP client private key or certificate. Use this parameter only if the KMIP client private key or certificate is encrypted. Available starting with version 5.0.9-8.

Configuration file	security.kmip.connectRetries
Command line	`kmipConnectRetries`
Type	int
Description	Defines how many times to retry the initial connection to the KMIP server. The max number of connection attempts equals to `connectRetries + 1`. Default: 0. The option accepts values greater than zero. Use it together with the `connectTimeoutMS` parameter to control how long `mongod` waits for the response before making the next retry.

Configuration file	security.kmip.connectTimeoutMS
Command line	`kmipConnectTimeoutMS`
Type	int
Description	The time to wait for the response from the KMIP server. Min value: 1000. Default: 5000. If the `connectRetries` setting is specified, the `mongod` waits up to the value specified with `connectTimeoutMS` for each retry.

Configuration file	security.kmip.activateKeys
Command line	`kmipActivateKeys`
Type	boolean
Description	When enabled, Percona Server for MongoDB activates a newly created master encryption key or verifies that the existing master key is in the Active state at startup. It also initiates the key state polling. Enabled by default. Available starting with version 5.0.28-24.

Configuration file	security.kmip.keyStatePollingSeconds
Command line	`kmipKeyStatePollingSeconds`
Type	int
Description	The period in seconds to check the state of the master encryption key. Default: 900. If the master encryption key is not in the Active state, the node logs the error and shuts down. Available starting with version 5.0.28-24.

Configuration¶

Considerations¶

Make sure you have obtained the root certificate, and the keypair for the KMIP server and the mongod client. For testing purposes you can use the OpenSSL to issue self-signed certificates. For production use we recommend you use the valid certificates issued by the key management appliance.

Procedure¶

To enable data-at-rest encryption in Percona Server for MongoDB using KMIP, edit the /etc/mongod.conf configuration file as follows:

security:
  enableEncryption: true
  kmip:
    serverName: <kmip_server_name>
    port: <kmip_port>
    clientCertificateFile: </path/client_certificate.pem>
    clientKeyFile: </path/client_key.pem>
    serverCAFile: </path/ca.pem>
    keyIdentifier: <key_name>

Alternatively, you can start Percona Server for MongoDB using the command line as follows:

$ mongod --enableEncryption \
  --kmipServerName <kmip_servername> \
  --kmipPort <kmip_port> \
  --kmipServerCAFile <path_to_ca_file> \
  --kmipClientCertificateFile <path_to_client_certificate> \
  --kmipClientKeyFile <path_to_client_private_key> \
  --kmipKeyIdentifier <kmip_identifier>

Upgrade considerations¶

To version 5.0.11-10 and higher¶

With the kmipKeyIdentifier option becoming optional in version 5.0.11-10, the standard upgrade procedure doesn’t work if you are upgrading from version 5.0.10-9 and earlier.

For Percona Server for MongoDB 5.0.13-11 and higher, follow the standard upgrade procedure

This section provides upgrade instructions from Percona Server for MongoDB 5.0.10-9 or lower to Percona Server for MongoDB version 5.0.11-10 and higher.

For a single-node deployment, use the mongodump / mongorestore tools to make a backup before the update and to restore from it after binaries are updated.

For replica sets, data must be re-encrypted with the new key during the upgrade. Go through the encrypting existing data steps but perform the minor upgrade between steps 1 and 2 to replace the mongod binary.

To version 5.0.28-24 and higher¶

Percona Server for MongoDB 5.0.28 and subsequent versions tolerate already existing Pre-Active master keys as follows: if at startup Percona Server for MongoDB detects that the data directory is encrypted with an existing master key in the Pre-Active state, it logs a warning and continues to operate as usual. In that case, Percona Server for MongoDB does not do periodic key state polling regardless the value specified for the kmipKeyStatePollingSeconds option. Read more about key state polling.

We recommend to either rotate a master encryption key or manually change the existing key to the Active state. You can also explicitly set the security.kmip.activateKeys configuration file option to ensure that only the active keys are used. This one-time operation smooths the major upgrade flow.

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