Cryptosystems
Cryptosystem: algorithm for encrypting plaintext into ciphertext, and decrypting, using keys.
Cryptographic protocol: exchange of messages for distributing keys or applying a cryptosystem to data.
Symmetric-key cryptosystem: the same key is used for encrypting and decrypting.
- Examples: DES, IDEA, Skipjack
Public-key cryptosystem: different keys are used for encrypting and decrypting. The encryption key may be made public.
- Examples: RSA, El Gamal, Elliptic curve