-----Original Message----- From: boost-bounces@lists.boost.org [mailto:boost-bounces@lists.boost.org] On Behalf Of Scott McMurray Sent: Tuesday, May 11, 2010 4:21 PM To: boost@lists.boost.org Subject: Re: [boost] Namespace for a Boost Hashing Library
On 11 May 2010 05:23, Paul A. Bristow <pbristow@hetp.u-net.com> wrote:
And there are other related hash functions like ISBN and Visa card check characters that could usefully be provided
in
the same name/space?
Things are set up to give a digest in a way that can easily and portably be read from and written to an octet stream (like a socket or file) as a check on an entire message. There's a fundamental assumption that the input could be arbitrarily long, and currently the output is assumed to be a multiple of 8 bits.
So in theory yes, but practically a different set of concepts might be better, given the different properties of the inputs and the small size of the outputs for things that are more like parity checks.
(BTW Is there interest in these functions for a GSoC?)
New hash functions would definitely be possible as a GSoC, but it would almost certainly have to be plural. With the concepts and infrastructure already in place, adding a new checksum is usually a pretty simple task.
Well there are several in very common use, for example those listed at http://www.augustana.ab.ca/~mohrj/algorithms/checkdigit.html Verhoeff's Dihedral Group D5 Check scheme is a bit more complicated than some. And *testing* is a vital feature of Boost quality software - and quite a bit of work. I would have thought that many people who could make use of these - perhaps in ways that are not common at present (part numbers, error checked GPS coordinates ...). But what do others think? Paul --- Paul A. Bristow Prizet Farmhouse Kendal, UK LA8 8AB +44 1539 561830, mobile +44 7714330204 pbristow@hetp.u-net.com