<P> In the development of DES, NSA convinced IBM that a reduced key size was sufficient; indirectly assisted in the development of the S - box structures; and certified that the final DES algorithm was, to the best of their knowledge, free from any statistical or mathematical weakness . </P> <P> However, it also found that </P> <P> NSA did not tamper with the design of the algorithm in any way . IBM invented and designed the algorithm, made all pertinent decisions regarding it, and concurred that the agreed upon key size was more than adequate for all commercial applications for which the DES was intended . </P> <P> Another member of the DES team, Walter Tuchman, stated "We developed the DES algorithm entirely within IBM using IBMers . The NSA did not dictate a single wire!" In contrast, a declassified NSA book on cryptologic history states: </P>

The des algorithm is an example of what type of cryptography