The GenDES package is a collection of routines for exploring DES, for computer-aided design related to DES secure symmetric-key block ciphers which allow to encrypt 64-bit block of data with the key of maximal length from 768 to 2359 bits, and for encrypting files by means of the old and generalized form of this algorithm, using Maple. The package is a noteworthy tool suitable for engineers, teachers and students who deal with symmetric-key iterative block ciphers design.