A
cryptosystem is (formally) a 5-tuple {
P,
C,
K,
E,
D} such that:
- P is the finite set of all possible plaintexts x.
- C is the finite set of all possible ciphertexts y.
- K is the keyspace (the finite set of all possible keys) k.
- E and D are the finite sets of encryption and decryption functions, respectively:
For each key k in K, there exists an encryption rule ek : P --> C and a decryption rule dk : C --> P such that, for any plaintext x in P, dk(ek(x)) = x.
(Part of the Everything2 Crypto Project)