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New in version 4.2.

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

Adds a data encryption key to the key vault associated to the database connection. Client-side field level encryption uses data encryption 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. Requires specifying a Customer Master Key (CMK) to customerMasterKey.

Specify local for a locally managed key.

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

customerMasterKey string

The identifier for the Customer Master Key (CMK) to use for encrypting the data encryption key. Required if keyManagementService is aws.

Specify the full Amazon Resource Name (ARN) of the master key. createKey() requests the AWS KMS encrypt the data encryption 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.

Changed in version 4.2.3: This parameter has no effect if keyManagementService is local and can be safely omitted. Prior to MongoDB 4.2.3, if keyManagementService is local this parameter must be an empty string ".

keyAltName array of strings


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

The getKeyVault() method automatically creates a unique index on the keyAltNames field with a partial index filter for only documents where keyAltNames exists.

returns:The UUID unique identifier of the created data encryption key.


Requires Configuring Client-Side Field Level Encryption on Database Connection

The mongo client-side field level encryption 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 encryption key using the locally managed key:

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

If successful, createKey() returns the UUID of the new data encryption key. To retrieve the new data encryption key document from the key vault, either: