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Information Security: DES and Rijndael Protocol

1.What is DES? What is triple DES? How did the Rijndael protocol enhance DES?

2.What are substitution ciphers? How do they differ from one-time pads (OTP)? Which is better for the IS manager to employ and why?

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See the attached file.
DES stands for Data Encryption Standard and was the cipher selected to encrypt government information in 1976. It is a block cipher, which means that it uses a fixed length block. Therefore if you put in 128 bits of plaintext data, you will get back 128 bits of encrypted data. Block ciphers also use a symmetric key. Symmetric key ciphers are a class of ciphers that use similar or identical keys for decryption and encryption.
DES uses a block size of 64 bits, with 8 of those used of parity checks. As a result, DES uses a key size of only 56 bits. By 1998, DES had proven to be too insecure when a special DES breaking computer designed by the Electronic Frontier Foundation was able to break DES in only a few days.
Triple DES encrypts blocks 3 times, using 2 different cipher keys. This produces 112 bit keys and 80 bit security. DES is still considered secure.
The Advanced Encryption Standard (AES) ...

Solution Summary

The solution discusses what is DES and how Rijndael protocol enhances DES.