As opposed to public-Key cryptography, a cryptographic method in which the same Key is used to encrypt and decrypt the message. Private-Key algorithms include the obsolescent Data Encryption Standard (DES), triple-DES (3DES), the Advanced Encryption Standard (AES), also Known as Rijndael, Blowfish, Twofish RC2, RC4, RC5 and RC6. A problem with private-Key cryptography is that the emitter and the recipient of the message must agree secretly on a common Key beforehands but how can they do so? Public-Key cryptography gives an answer to this problem. (2003-04-12)