Has DES been broken down

Question

Has DES been broken down?

Answer 1

No easy attack on DES has been explored, despite the efforts of various researchers over various years. The obvious technique of attack is brute-force comprehensive search of key space; this acquires 255 steps on the average. Early on it was suggested that the rich and powerful enemy could build the special-purpose computer skilled of breaking DES by comprehensive search in a reasonable amount of time. Afterward, Hellman [Hel80] showed the time-memory trade-off which permits enhancement over comprehensive search if memory space is plentiful, after a comprehensive precomputation. These ideas fostered doubts regarding the security of DES.

There were as well accusations which the NSA had intentionally weakened DES. Despite such suspicions, no feasible manner to break DES faster than comprehensive search was discovered. The cost of the specialized computer to perform comprehensive search (requiring 3.5 hours on average) has been predictable by Wiener at 1 million dollars.