A form of cryptography that involves the use of a single key to both encrypt and decrypt data. This key is frequently based on a password phrase. The only key that can decrypt ciphertext (encrypted data) is the same one used to encrypt it - thus it is important that anyone who needs to decrypt your information gets the key over a secure communications medium.
A form of cryptography in which the key required for encrypting is the same as the key required for decrypting. The term describes all traditional forms of encryption, i.e. those in use before the 1970s.
Encryption method that uses the same random number ( key) in conjunction with a mathematical formula to encode and decode data.