Not true at all. Cryptography Research has patented most of the implementation techniques required to do hardware crypto without being susceptible to differential power analysis (btw: that? My favorite business model ever!). That was almost pure systems research.

Something as arcane as DES is not a "natural law". Crypto algorithms aren't pre-existing (show me a naturally occuring physical process that can be described by a crypto alogrithm), they're not obvious to even experts in the field, and people spend a lot of time trying to get them right. That's the very definition of patentable.

[I know DES isn't patented, and there's plenty of good reasons why you don't want a patented crypto algorithm, but I think they certainly qualify.]