Basic Cryptographic Concepts

摘要

The basic goal of encryption algorithms is to transmit some data, termed the plaintext, in such a way that it cannot be recovered by unauthorized agents. This is done by using a cryptographic key and algorithm to convert the plaintext into encrypted data or ciphertext. Only authorized agents should be able to convert the ciphertext back to the plaintext. There are two general types of key-based algorithms: symmetric and asymmetric (or public-key). In most symmetric algorithms, the encryption key and the decryption key are the same. These keys are often called session keys.