<cryptography> 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.
