Virtual Private Network
A VPN is an example of applied cryptography that typically exchanges secure data over the Internet. Encryption is needed to make the connection virtually private. A popular VPN technology is IPSec, which commonly uses the DES, Triple DES or AES encryption algorithms. DES uses 56-bit keys, and Triple DES applies the key three times to achieve an effective key length of 168 bits. AES is a new standard adopted in 2001 that uses keys that can be 128, 192 or 256 bits long and a block size of 128 bits (vs. 64-bit blocks used in DES).