When the Data Encryption Standard (DES) was created, the National Security Agency made sure that it was weak enough that they could break it.  The Data Encryption Standard was a result of Horst Feistel’s product, Lucifer.  Lucifer was a machine that could encrypt data, making the encryption nearly impossible to decrypt.  In 1976, the NSA made the decision to limit the DES to 100,000,000,000,000,000 possible keys.

The strength of a cipher is directly correlated to the number of possible keys.  With so many possible keys, no common computer could possibly decrypt a DES encrypted cipher.  Most powerful computers are capable of finding the correct key when the number of possible keys is only 1,000,000.  By limiting the number of possible keys to a number higher than what a typical computer is capable of breaking, the NSA justified its decision.  The DES was created so that all businesses could communicate securely and reliably.  Even with a limit on the number of possible keys, the same goal was achieved.  Though the security was less than optimal, the security would still be unbreakable.   More importantly, if the DES were too strong, the government and NSA would be incapable of tapping information.  As we’ve previously discussed in Little Brother, there are times where the government needs full access to all forms of communication.  If the NSA did not limit the number of possible keys, it would put domestic and international security at risk.  In this way, the NSA was justified in making sure it was weak enough that they could break it.

Image: "Bokeh Command" by Robert S. Donovan, Flickr (CC)