private credential/ecash thread on slashdot (Re: announce: credlib library with brands and chaum credentials)

Adam Back adam at
Tue Feb 20 16:40:29 PST 2007

Credentica (Stefan Brands ecash/credentials) U-prove library and
open source credlib library implementing the same are on slashdot:

Maybe some list readers would like to inject some crypto knowledge
into the discussion.  

There is quite some underinformed speculation as critique on the
thread...  Its interesting to see people who probably understand SSL,
SMIME and stuff at least at a power user if not programmer level, try
to make logical leaps about what must be wrong or limited about
unlinkable credential schemes.  Shows the challenges faced in
deploying this stuff.  Cant deploy what people dont understand!


On Fri, Feb 16, 2007 at 11:14:39AM -0500, Adam Back wrote:
> Hi
> I implemented Chaumian and Brands credentials in a credential library
> (C code, using openSSL).  I implemented some of the pre-computation
> steps.  Have not made any attempt so far to benchmark it.  But thought
> I could take this opportunity to make it public.  I did not try to
> optimize so far.  One optimization opportunity at algorithm level, is
> you dont need witness indistinguishability on a single attribute
> credential, which saves some of the computations.
> Ben, if you have a partial implementation of Camenisch credentials,
> you could maybe do some comparisons of that against this C
> implementation.

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