Differential cryptanalysis was discovered initially by IBM while working on DES. The NSA made design alterations to DES to make it more resistant to DCA. Howe

Differential cryptanalysis was discovered initially by IBM while working on DES. The NSA made design alterations to DES to make it more resistant to DCA. However they didn’t publish those design decisions because they would reveal the existence of the technique, which at the time was applicable to many other ciphers including nearly all Soviet ciphers. The NSA didn’t backdoor DES the key shortening and the addition of parity bits was an attempt to make it more resilient to DCA while making it only slightly more susceptible to brute force attacks. It’s also important to note that DES was a 1970’s cipher which survived long enough to be relevant, even a 1080ti would take 2 or more days to crack a single DES key and its considerably more powerful than likely all the super computers in the world combined in say 1983. The NSA isn’t your friend for sure but they know exactly what they are doing.