Crypto FAQ : What is encryption? What is decryption?

Encryption is the process of encoding of messages or other information, referred to as plaintext, into ciphertext, in a manner so that only the encoder or other authorized parties can convert the ciphertext back to plaintext. Stated otherwise, ciphertext is encoded (i.e., encrypted), whereas plaintext is decoded (i.e., decrypted). Although encryption does not inherently prevent message interception or information access, in effect it denies content to interceptors who may be adversarial in nature.

Decryption is the inverse process of encryption, in which encoded messages, referred to as ciphertext, are decoded into plaintext, so that their original unencrypted content may be read.