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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:The UUID unique identifier of the created data key.


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 is intended for rapid evaluation of client-side field level encryption. For more complete examples appropriate for development and production environments, see Create a data encryption key.

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 and loads it into the mongo shell:

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

mongo --nodb --shell --eval "var TEST_LOCAL_KEY='$TEST_LOCAL_KEY'"

Create the client-side field level encryption object using the generated local key string:

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

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 the UUID of the created data key. To retrieve the created data key document from the key vault, either: