If the NSA activity we're talking about is anything like what is described in the Wikipedia article on DES, then "has inserted weaknesses" is entirely inappropriate wording.
Really? When you make standard 256 times weaker then it could be otherwise it's not “inserting weaknesses”? How do you call said process?
Note that in story with DES quite visible change made standard weaker and opaque change didn't but it does not change the principal position: standard was changed at the NSA request and nobody outside NSA had any idea for why said request was made in the first place.
The other was to reduce the key length from 64 bits to 48. IBM rejected that.
Right. 48 bits instead of 64 means it's 65536 times easier to crack.
NSA then proposed 54 bits and IBM found that to be better than 64 and accepted it.
NSA, of course, proposed 56 bits, not 54 and, more importantly, IBM never agreed and never claimed 56 bits are better than 64—that's an absurd claim. Of course 56 bits cypher are weaker then 64 bits. 256 times (if there are no other substantial differences). But IBM decided that it's better to accept 56bit compromise rather then try to insist on 64bits and see their proposal thrown out.
The article doesn't tell the process by which ANSI and ISO adopted it, but I see no evidence that NSA was involved.
Why would NSA involved? The deed was done much earlier—when 64bits were replaced with “good enough” 56bits and S-boxes were altered. It does not look like S-boxes changes were nefarious (we still don't really know), but problem with change from 64bits to 56bits is self-evident to anyone who knows how cryptography works.
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