A standard DES encryption key is 56 bits long. Although considered very secure at the time of it's release in the mid 1970's, advancement in computer technology has assisted in the development of techniques to crack DES keys in meaningful time periods.
In 1999 a distributed computing project managed to crack a DES key in 22 hours and 15 minutes. DES encryption is no longer considered strong enough for high security applications.
AES keys can be 128, 192 or 256 bits long. Most commonly the 128 bit key length is used - giving a total of 3.4 x 10^38 possible keys. AES development has been a co-operative venture between the U.S. government and the private industry sector resulting in a encryption system that is royalty free.
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