Cryptosystem A cryptosystem is a five -tuple(P, C, K, E,D), where the following conditions are satisfied 1. P is a finite set of possible plain teXts 2. C is a finite set of possible ciphertexts 3. K, the keyspace, is a finite set of possible keys 4. For each kEK, there is an encryption rule eK E E and a corresponding decryption rule dk∈D. Each ek:P> C and d,:C→Pare functions such that dex( x )=x for every plaintext X∈PCryptosystem • A cryptosystem is a five -tuple (P, C, K, E, D), where the following conditions are satisfied: • 1. P is a finite set of possible plain texts • 2. C is a finite set of possible ciphertexts • 3. K, the keyspace, is a finite set of possible keys • 4. For each kK, there is an encryption rule eK  E. and a corresponding decryption rule dK  D). Each eK : P → C and dK : C → P are functions such that dK(eK(x)) = x for every plaintext x  P