Encryption is enabled for all backups.

Client side encryption
Encryption of data is performed by the Commvault agent installed on your server before being transmitted across the network. During a restore, data is decrypted on your server. Where commvault creates additional copies of a backup job (for example to tape), the data retains its original encryption.

AES256 Cipher
The implementation details of the cipher are: AES 256 - CBC mode. Each 64KB block is a single CBC chain. IVs are randomly generated using a ANSI 9.31 random number generator. There is no extra special management of IVs. They are included into the cipher text stream. Integrity for each up-to-64KB encrypted data block is checked with CRC32.

Each backup chunk (a block of storage space on tape or disk) has its own random key. This means there is an extremely minimal chance of multiple jobs being lost even if one key is compromised. Keys are stored in encrypted form within the Commcell database.

The AES 256bit cipher is recommended by:

• NHS 'HSCIC Approved Cryptographic Algorithms Good Practice guide' (Section 3.1)
• UK Information Commisioners Office (FIPS 140-2).
• US & Canadian government.

The commvault implementation has been approved and validated by NIST to the US Federal Information Processing Standard (FIPS 140-2).

FIPS approval
The US National Institute of Standards and Technology has CommVault's certification under the list of Validated FIPS 140-1 and FIPS 140-2 Cryptographic Modules that have been tested using the cryptographic module validation program (CMVP). AES 256 is listed as an approved algorithm.

Performance Considerations
Traditional encrypted backups suffer a 40-50% reduction in throughput, however encrypted deduplicated backup throughput is reduced by only around 10% as there is far less data to encrypt.

Backup retention
Backup retention defines how long a restore point remains avalible for recovery. It should be defined to ensure compliance with data protection, business, funding body and audit requirements.

For example, some data may have to maintained for an extended period (ie. several years for financial data), whilst other data may have to be deleted in less than thirty days (ie. medical data retention from research projects can be as little as fourteen days).

How data is deleted
Once a backup job exceeds its retention date, unique blocks associated with the job are deleted from the system. The Commcell database entry and associated key are deleted. Open keys in memory are deleted using memset().

If you have any queries about our backup service, please contact us.