Ciphers Question:

Since there are 256 possible DES keys the chance of picking a weak or semi-weak key at random is 2-52. As long as the user-provided key is chosen entirely at random, they can be safely ignored when DES is used for encryption. Despite this, some users prefer to test whether a key to be used for DES encryption is in fact a weak key. Such a test will have no significant impact on the time required for encryption.