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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.


ClientEncryption.decrypt decrypts the encryptionValue if the current database connection was configured with access to the Key Management Service (KMS) and key vault used to encrypt encryptionValue.

decrypt has the following syntax:

clientEncryption = db.getMongo().getClientEncryption()


The encryptedValue must be a binary data object with subtype 6 created using client-side field level encryption.

returns:The decrypted value.


Read operations issued from a database connection configured with access to the correct Key Management Service (KMS) and Key Vault can automatically decrypt field values encrypted using ClientEncryption.encrypt(). Clients only need to use decrypt() to decrypt Binary subtype 6 values not stored within a document field.

Enable 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.



To mitigate the risk of the AWS Access Key or AWS Secret Key leaking into logs, consider specifying an environment variable containing the required values as part of the mongo startup. For example, the following operation loads the AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY environment variables into local variables in the mongo shell:

mongo --eval "
  " \

Use the created AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY variables in the shell to reference the AWS credentials.

The following operation issued from the mongo shell:

  • Establishes a connection to the cluster with client-side field level encryption enabled.
  • Retrieves the ClientEncryption object using the getClientEncryption() constructor on an encryption-enabled connection.
  • Decrypts a value encrypted using ClientEncryption.encrypt().
clientSideFLEOptions = {
  "keyVaultNamespace" : "encryption.dataKeys",
  "kmsProviders" : {
    "aws" : {
      "accessKeyId" : "AWS_ACCESS_KEY_ID",
      "secretAccessKey" : "AWS_SECRET_ACCESS_KEY"

encryptedClient = Mongo(

clientEncryption = encryptedClient.getClientEncryption();


If successful, decrypt returns the decrypted value:


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