Managing Encryption Keys and Zones

Interacting with the KMS and creating encryption zones requires the use of two new CLI commands: hadoop key and hdfs crypto. The following sections will help you get started with creating encryption keys and setting up encryption zones.

Before continuing, make sure that your KMS ACLs have been set up according to best practices. For more information, see Configuring KMS Access Control Lists.

Validating Hadoop Key Operations

Use hadoop key create to create a test key, and then use hadoop key list to retrieve the key list: 
$ sudo -u <key_admin> hadoop key create keytrustee_test
$ hadoop key list

Creating Encryption Zones

Once a KMS has been set up and the NameNode and HDFS clients have been correctly configured, use the hadoop key and hdfs crypto command-line tools to create encryption keys and set up new encryption zones.

  • Create an encryption key for your zone as the keyadmin for the user/group (regardless of the application that will be using the encryption zone): 
    $ sudo -u hdfs hadoop key create <key_name>
  • Create a new empty directory and make it an encryption zone using the key created above. 
    $ sudo -u hdfs hadoop fs -mkdir /encryption_zone
$ sudo -u hdfs hdfs crypto -createZone -keyName <key_name> -path /encryption_zone
    You can verify creation of the new encryption zone by running the -listZones command. You should see the encryption zone along with its key listed as follows: 
    $ sudo -u hdfs hdfs crypto -listZones
/encryption_zone    <key_name>

For more information and recommendations on creating encryption zones for each CDH component, see Configuring CDH Services for HDFS Encryption.

Adding Files to an Encryption Zone

You can add files to an encryption zone by copying them to the encryption zone using distcp. For example: 
sudo -u hdfs hadoop distcp /user/dir /encryption_zone

DistCp Considerations

A common use case for DistCp is to replicate data between clusters for backup and disaster recovery purposes. This is typically performed by the cluster administrator, who is an HDFS superuser. To retain this workflow when using HDFS encryption, a new virtual path prefix has been introduced, /.reserved/raw/, that gives superusers direct access to the underlying block data in the filesystem. This allows superusers to distcp data without requiring access to encryption keys, and avoids the overhead of decrypting and re-encrypting data. It also means the source and destination data will be byte-for-byte identical, which would not have been true if the data was being re-encrypted with a new EDEK.

Copying data from unencrypted locations

By default, distcp compares checksums provided by the filesystem to verify that data was successfully copied to the destination. When copying from an encrypted location, the file system checksums will not match because the underlying block data is different. This is true whether or not the destination location is encrypted or unencrypted.

In this case, you can specify the -skipcrccheck and -update flags to avoid verifying checksums. When you use -skipcrccheck, distcp checks the file integrity by performing a file size comparison, right after the copy completes for each file.

Deleting Encryption Zones

To remove an encryption zone, delete the encrypted directory: 
$ sudo -u hdfs hadoop fs -rm -r -skipTrash /encryption_zone

Backing Up Encryption Keys

If you are using the Java KeyStore KMS, make sure you regularly back up the Java KeyStore that stores the encryption keys. If you are using the Key Trustee KMS and Key Trustee Server, see Backing Up and Restoring Key Trustee Server and Clients for instructions on backing up Key Trustee Server and Key Trustee KMS.