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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" ]


The Key Management Service (KMS) to use for retrieving the Customer Master Key (CMK). Accepts the following parameters:

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

string or document

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

Provide the CMK as follows depending on your KMS provider:

  • For the Amazon Web Services KMS, specify the full Amazon Resource Name (ARN) of the master key as a single string.
  • For the Azure Key Vault KMS, specify a document containing the following key value pairs:

    • keyName - The Azure Key Vault Name
    • keyVaultEndpoint - The DNS name of the Azure Key Vault to use
    • keyVersion - Optional. The version of the key specified in keyName, if applicable

    New in version 5.0.

  • For the Google Cloud Platform KMS, specify a document containing the following key value pairs:

    • projectId - The GCP project name
    • location - The location of the KMS keyring
    • keyRing - The name of the KMS keyring (often 'global')
    • keyName - The name of the key to use
    • keyVersion - Optional. The version of the key specified in keyName, if applicable

    New in version 5.0.

createKey() requests that the KMS encrypt the data encryption key material using the specified CMK. If the CMK does not exist or if the ClientSideFieldLevelEncryptionOptions configuration does not have sufficient privileges to use the 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 ".

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.

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:

The following example is intended for rapid evaluation of client-side field level encryption. For specific examples of using KeyVault.createKey() with each supported KMS provider, 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')")
mongosh --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:

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