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)
