Must there is a test for weak keys in DES

Question

Must there is a test for weak keys in DES?

Answer 1

As there are 256 possible DES keys the possibility of picking a weak or semi-weak key at arbitrary is 2-52. As long as the user-provided key is selected wholly at random, they can be safely ignored whenever DES is employed for encryption. In spite of this, some users favor to test whether a key to be employed for DES encryption is however a weak key. Such a test will have no important impact on the time needed for encryption.