Cryptography in which a single key is used. The key algorithms are DES, IDEA and !TwoFish?, etc. These systems have encrypt data with key in such a way that recovering the data without the key is very, very hard. (These algorthims are used in many PublicKeyEncryption systems too, but aren't key parts of the system.)
Compare: PublicKeyEncryption
2 pages link to ConventionalCryptography: