Scrambling a WLAN's data as it leaves the AP, and then unscrambling it when it arrives at the client, requires an encryption method. The popular RC4 has already been discussed, but sturdier, stronger encryption methods are out there and in use in WLAN systems, as described next.
Data Encryption Standard (DES)
Data Encryption Standard (DES) is an encryption method that uses a secret key. It is so hard to break (it provides 72 quadrillion possible keys) that the U.S. government forbids its exportation to other countries. It is tough to break because the key is randomly chosen from an enormous pool.
DES applies a 56-bit key to each 64-bit block of data. This is considered strong encryption. Of course strong is a relative term, and if someone is really determined and has the resources, it is possible to crack DES. Many organizations employ triple DES, which applies three keys in succession.
Advanced Encryption Standard (AES)
Advanced Encryption Standard (AES) is poised to become the de facto encryption standard. AES applies 128-, 192-, or 256-bit keys to 128-, 192-, or 256-bit blocks of data.
As of 2004, there had been no reported cracks of AES, and it is the first time that the U.S. Government's National Security Agency (NSA) authorized an encryption tool for transmission of top-secret, classified information.