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New in version 4.2.


Client-Side Field Level Encryption is available as a beta. The contents of this page may change during the beta period.

KeyVault.createKey(keyManagementService, customerMasterKey[, "keyAltName"])

Adds a data key to the key vault associated to the database connection. Client-side field level encryption uses data keys for supporting encryption and decryption of field values.

createKey() has the following syntax:

keyVault = db.getMongo().getKeyVault()

  [ "keyAltName" ]
Parameter Type Description
keyManagementService string


The Key Managmenet Service (KMS) to use for retrieving the Customer Master Key (CMK).

Specify aws for Amazon Web Service KMS.

Specify local for a locally managed single-key KMS.

If the database connection was not configured with the specified KMS, data key creation fails.

customerMasterKey string


The identifier for the CMK to use for encrypting the data key.

  • For, specify the full Amazon Resource Name (ARN) of the master key. createKey() requests the AWS KMS encrypt the data key material with the specified CMK.

    If the CMK does not exist or if the KMS configuration does not provide access to that CMK, createKey() returns an error.

  • For keyManagementService.local, specify an empty string "". The local KMS uses only the local key specified as part of the database connection for encrypting data keys.

keyAltName array of strings


The alternative name for the data key. Use keyAltName to improve findability of a specific data key, or as an analog to a comment.

keyAltName must be unique. getKeyVault creates a unique index on keyAltName to enforce uniqueness of keyAltName.

returns:A WriteResult object.


Requires Configuring Client-Side Field Level Encryption on Database Connection

The mongo client-side field level encrytion methods require a database connection with client-side field level encryption enabled. If the current database connection was not initiated with client-side field level encryption enabled, either:

  • Use the Mongo() constructor from the mongo shell to establish a connection with the required client-side field level encryption options. The Mongo() method supports both Amazon Web Services and Local Key Management Service (KMS) providers for Customer Master Key (CMK) management.


  • Use the mongo shell command line options to establish a connection with the required options. The command line options only support the AWS KMS provider for CMK management.


The following example uses a locally managed KMS for the client-side field level encryption configuration. See Create a Data Key for more complete examples of data key creation with Amazon Web Services KMS and locally managed KMS.

Configuring client-side field level encryption for a locally managed key requires specifying a base64-encoded 96-byte string with no line breaks. The following operation generates a key that meets the stated requirements:

echo "$(head -c 96 /dev/urandom | base64 | tr -d '\n')"

Create a mongo shell session using the --nodb option and issue the following operation from that shell:

mongo --nodb

From the mongo shell session, issue the following operation to create the client-side field level encryption configuration object. Replace the key string with a valid base64-encoded 96-byte string, such as the one genereated using the code provided at the beginning of this example:

var ClientSideFieldLevelEncryptionOptions = {
  "keyVaultNamespace" : "encryption.__dataKeys",
  "kmsProviders" : {
    "local" : {
      "key" : BinData(0, "96-BYTE_LOCAL_KEY_STRING")

Use the Mongo() constructor to create a database connection with the client-side field level encryption options. Replace the mongodb:// URI with the connection string URI of the target cluster.

encryptedClient = Mongo(

Retrieve the keyVault object and use the KeyVault.createKey() method to create a new data key using the locally managed key:

keyVault = encryptedClient.getKeyVault()
keyVault.createKey("local", "", ["data-encryption-key"]

If successfull, createKey() returns a WriteResult. To retrieve the created key: