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  • Behavior
  • Example

New in version 4.2.


Returns the ClientEncryption object for the current database collection. The ClientEncryption object supports explicit (manual) encryption and decryption of field values for Client-Side field level encryption.

getClientEncryption() has the following syntax:

Returns:The ClientEncryption object for current database connection.

Use the ClientEncryption object to access the following explicit encryption methods:

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 getKeyVault() method automatically creates a unique index on the keyAltNames field with a partial index filter for only documents where keyAltNames exists. getKeyVault() creates this index in the key vault collection. This prevents any two data encryption keys in the same key vault from having the same key alternative name and therefore avoids ambiguity around which data encryption key is appropriate for encryption/decryption.


Do not drop the unique index created by getKeyVault(). Client-side field level encryption operations depend on server-enforced uniqueness of keyAltNames. Removing the index may lead to unexpected or unpredictable behavior.

The following example uses a locally managed KMS for the client-side field level encryption configuration.

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(

Use the getClientEncryption() method to retrieve the client encryption object:

clientEncryption = encryptedClient.getClientEncryption()

For complete documentation on initiating MongoDB connections with client-side field level encryption enabled, see Mongo().

← KeyVault.getKeyByAltName()

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