Using CA Tape Encryption in Your z/OS Environment › Integrated Compression for Symmetric Key Encryption

Integrated Compression for Symmetric Key Encryption

The integrated compression feature of CA Tape Encryption compresses files before they are encrypted and expands files after they have been decrypted. This feature lets you compress files selectively using standard compression methods. Compression and expansion run transparently with no user intervention required. No external compression programs are required. The available compression methods are based on compression methods used by CA Compress Data Compression, plus additional algorithms intended to provide IDRC-like compression for situations where tape utilization is a higher priority than CPU consumption.

You can compress all files that are candidates for encryption, or compress files selectively based on the compression attributes specified for each symmetric key. The available compression methods include standard software compression algorithms and IBM hardware-driven compression methods.

Files are compressed before they are encrypted because encrypted files are not good candidates for compression. Compressed files can be encrypted with no loss of security. It is advantageous to compress files before they are encrypted because the resulting files are smaller than if they were compressed after they were encrypted.

Most tape vendors today provide Improved Data Recording Capability (IDRC) compression as a hardware component of their drives. However, encryption processing severely reduces the effectiveness of the compression performed. When data is encrypted by CA Tape Encryption (or any other encryption product) the data is transformed into a format that cannot be compressed well. For this reason you may observe that files that previously fit on a single tape now extend to an additional cartridge. The integrated compression feature of CA Tape Encryption lets you perform compression on the z/OS host prior to encryption. This permits you to keep files on a single cartridge and reduces the overall amount of media used.

Note: The compression feature supports the use of symmetric keys. Compression is not supported for B2B keys and code book keys.