On 08.12.24 12:04, Andrey Semashev via Boost wrote:
On 12/7/24 03:16, Peter Dimov via Boost wrote: However, I still don't see the benefit of extending through subsequent calls to finalize() when the internal state is not larger than the hash value. Any input data that produce a particular hash value v will also produce the same extended value xv. And that would be true whether you perform extension through additional calls to finalize(), duplicating the baseline hash value or zero-extension. Of course, the contribution to uniqueness of individual bits in xv would be different in each case, but as far as the uniqueness of xv as a whole is concerned, there seems to be no difference.
One property of a good N bit hash is that picking M bits from that hash, where M < N, produces a good M bit hash. This is not the case when the original hash uses zero-extension, since the picked bits could all come from zero-extension. -- Rainer Deyke - rainerd@eldwood.com