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ClientEncryption.decrypt()

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New in version 4.2.

beta

Client-Side Field Level Encryption is available as a beta. The contents of this page may change during the beta period.

ClientEncryption.decrypt(encryptedValue)

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()

clientEncryption.decrypt(encryptedValue)

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

returns:The decrypted value.

Behavior

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.

    or

  • 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.

Example

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:

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

Create a mongo shell session using the --nodb option and issue the following operation from that shell:

mongo --nodb

From the mongo shell session, issue the following operation to create the client-side field level encryption configuration object. Replace the key string with a valid base64-encoded 96-byte string, such as the one genereated using the code provided at the beginning of this example:

var ClientSideFieldLevelEncryptionOptions = {
  "keyVaultNamespace" : "encryption.__dataKeys",
  "kmsProviders" : {
    "local" : {
      "key" : BinData(0, "96-BYTE_LOCAL_KEY_STRING")
    }
  }
}

Use the Mongo() constructor to create a database connection with the client-side field level encryption options. Replace the mongodb://myMongo.example.net URI with the connection string URI of the target cluster.

encryptedClient = Mongo(
  "mongodb://myMongo.example.net:27017/?replSetName=myMongo",
  clientSideFLEOptions
)

Retrieve the ClientEncryption object and use the ClientEncryption.decrypt() method to decrypt a value encrypted by ClientEncryption.encrypt().

clientEncryption = encryptedClient.getClientEncryption();

clientEncryption.decrypt(BinData(6,"AmTi2H3xaEk8u9+jlFNaLLkC3Q/+kmwDbbWrq+h9nuv9W+u7A5a0UnpULBNZH+Q21fAztPpU09wpKPrju9dKfpN1Afpj1/ZhFcH6LYZOWSBBOAuUNjPLxMNSYOOuITuuYWo="))

If successful, decrypt() returns the decrypted value:

"123-45-6789"

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