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Simple Des

Simple Des is a block cipher which encrypts an 9 bit block of plaintext using a 10 bit key and outputs an 8 bit block of ciphertext.This Simple Des presents of structure of Simple Des; basic fuctions of Simple Des; crypanalysis of Simple Des and some things else.  | SIMPLE DES Simple DES is a block cipher which encrypts an 8-bit block of plaintext using a 10-bit key and outputs an 8-bit block of ciphertext. The encryption algorithm involves five functions executed in the following order 1. an initial permutation IP 2. a function fK 3. a switch function SW that switches two halves 4. the function IK again 5. the inverse IP-1 of permutation IP. Steps 2 and 3 use keys K1 and K2 resp. which are generated via a key generation algorithm. 1 KEY GENERATION Key generation involves three functions which are applied in a five step sequence in order to produce two subkeys 1. a permutation p 10 which permutes a 10-bit input 2. a left shift operation 3. an 8-bit permutation that produces an 8-bit output this gives the first subkey K1 4. again the output from step 2 is subjected to a second double left shift 5. an 8-bit permutation that produces a second 8-bit output this is the second subkey K2. Several alternatives could have been applied like either using a larger key or using two independent keys. 2 SIMPLE DES KEY