Re: [boost] Namespace for a Boost Hashing Library

Subject: Re: [boost] Namespace for a Boost Hashing Library
From: Paul A. Bristow (pbristow_at_[hidden])
Date: 2010-05-11 12:25:00

> -----Original Message-----
> From: boost-bounces_at_[hidden] [mailto:boost-bounces_at_[hidden]] On Behalf Of Scott McMurray
> Sent: Tuesday, May 11, 2010 4:21 PM
> To: boost_at_[hidden]
> Subject: Re: [boost] Namespace for a Boost Hashing Library
> 
> On 11 May 2010 05:23, Paul A. Bristow <pbristow_at_[hidden]> 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
[phone], mobile [phone]
pbristow_at_[hidden]