Simplified DES is a toy variant of the DES cipher introduced by Edward F. Schaefer in 1996 for educational purposes. It has an 8-bit block size and a 10-bit key, and uses two rounds, with two 4x2 bit S-boxes.
S-DES, or Simplified DES, is a "toy" variant of the DES block cipher developed and published by Edward F. Schaefer in 1996 for educational purposes. It has an 8-bit block size and a 10-bit key, and uses two rounds, with two 4x2 bit S-boxes.
S-DES is not designed to be a secure block cipher, and indeed it is easily broken using various techniques, including but not limited to brute force search of the keyspace. It is, however, useful for demonstrating the principles of operation of the DES cipher, and for practicing cryptanalytic techniques against a simple and easily attacked target.
References:
Schaefer, Edward F. "A simplified Data Encryption Standard algorithm", Cryptologia 20(1), pp. 77-84, 1996, doi:10.1080/0161-119691884799.
Stallings, William. Cryptography and Network Security (5th ed.), Prentice Hall 2010, ISBN-10: 0136097049. (Appendix G contains a description of S-DES.)
