Nonstop Volume Level Encryption Guide

A Encryption background
Encryption transforms plaintext data into encrypted data using an encryption key. Decryption
transforms encrypted data back into the plaintext form using a decryption key. Encrypted data is
secure because it cannot be decoded into plaintext form, in a reasonable amount of time, without
the decryption key. There are two types of encryption: asymmetric and symmetric.
Asymmetric, or public key, encryption
This technique uses a private/public key pair. The private key is kept secret, while the public
key is widely distributed. Data that is encrypted using the public key can only be decrypted
with the corresponding private key. RSA is an example of public key encryption.
Symmetric, or secret key, encryption
This technique uses a single key for both encryption and decryption. Blowfish, Defense Encryption
Standard (DES), triple DES, and Advanced Encryption Standard (AES) are typical secret key
examples. This type of encryption is best suited for large amounts of data, usually performed
in blocks. Symmetric encryption is subdivided into two classes, block ciphers and stream ciphers.
Stream ciphers encrypt character by character providing a continuous stream of encrypted
data whereas block ciphers operate on discrete blocks of data.
The algorithms used in symmetric encryption are two-way, meaning that decryption is the reverse
process of encryption. Symmetric block-level encryption, is sometimes referred to sometimes as a
block cipher. There are many block cipher designs such as Blowfish, DES, Triple DES, and AES.
The data to be encrypted is divided into blocks or groups of characters and the mathematical
functions applied to each block. Key length varies according to the cipher with DES having 56-bit
keys and AES having 128-, 192-, or 256-bit keys.
The volume level encryption product follows the IEEE 1619 (disk) and IEEE 1619.1 (tape) standards
using AES-XTS-256 and AES-CGM-256 encryption algorithms.
58 Encryption background