Early on in its development, why were some people concerned about DES? An algorithm that is arrived at by having a contest is not as secure as one developed in secret. It was developed by IBM, so people were worried about having to license it for general use. People were worried that the S-boxes were constructed in such a way as to allow someone with inside knowledge to break the cipher. It has been shown to be extremely susceptible to differential, linear, and algebraic cryptanalysis