People have had that reaction to NSA-endorsed cryptosystems ever since they withheld the derivation of the DES S-boxes for a number of years. Wikipedia states

People have had that reaction to NSA-endorsed cryptosystems ever since they withheld the derivation of the DES S-boxes for a number of years. Wikipedia states [1]: "The 8 S-Boxes of DES were the subject of intense study for many years out of a concern that a backdoor -- a vulnerability known only to its designers -- might have been planted in the cipher. The S-Box design criteria were eventually published (in Coppersmith 1994) after the public rediscovery of differential cryptanalysis, showing that they had been carefully tuned to increase resistance against this specific attack." [1] http://en.wikipedia.org/wiki/Substitution_box http://en.wikipedia.org/wiki/Substitution_box