Original: In cryptography, DES-X (or DESX) is a variant on the DES (Data Encryption Standard) block cipher intended to increase the complexity of a brute force attack using a technique called key whitening.
Simplified: In cryptography, DES-X (or DESX) is an alternative to the DES (Data Encryption Standard) block cipher designed to increase the complexity of a brute force attack using a technique called key whitening.