I suppose I don't understand your point. On one hand, you can have different algorithms for each of 32, 64, etc with potentially different pitfalls and usage requirements. On the other, you can have one algorithm that implements all of them. I wasn't trying to comment on how that should be exposed in the library (because crypto lib design is a whole 'nother topic), but I'm not opposed to it being explicit.

Same as CRCs, really. You can easily write a function that performs CRCs of any size and expose different parameterizations as CRC-8/16/32/64 etc.