see also credentica announcement about U-prove (Re: IBM donates new privacy tool to open-source)

Adam Back adam at
Wed Feb 14 18:35:53 EST 2007

Related to this announcement, (Stefan Brands' company)
has released "U-Prove", their toolkit & SDK for doing limited-show,
selective disclosure and other aspects of the Brands credentials.

(Also on Stefans blog

I believe Brands credentials are considerably more computationally
efficient and more general/flexible than Camenisch credentials.

(Re Hal's comment on the patent status of Camenisch credentials, as
far as I know patents apply to both systems).

Looks like you can obtain an evaluation copy of U-prove also.


On Sun, Feb 04, 2007 at 10:34:33AM -0800, "Hal Finney" wrote:
> John Gilmore forwards:
> >
> >
> > IBM donates new privacy tool to open-source
> >   By  Joris Evers
> >   Staff Writer, CNET
> >   Published: January 25, 2007, 9:00 PM PST
> >
> > IBM has developed software designed to let people keep personal  
> > information secret when doing business online and donated it to the  
> > Higgins open-source project.
> >
> >   The software, called "Identity Mixer," was developed by IBM  
> > researchers. The idea is that people provide encrypted digital  
> > credentials issued by trusted parties like a bank or government agency  
> > when transacting online, instead of sharing credit card or other  
> > details in plain text, Anthony Nadalin, IBM's chief security architect,  
> > said in an interview.
> > ...
> I just wanted to note that the idemix software implements what we
> sometimes call Camenisch credentials.  This is a very advanced credential
> system based on zero knowledge and group signatures.  The basic idea is
> that you get a credential on one pseudonym and can show it on another
> pseudonym, unlinkably.  More advanced formulations also allow for
> credential revocation.  I don't know the specifics of what this software
> implements, and I'm also unclear about the patent status of some of the
> more sophisticated aspects, but I'm looking forward to being able to
> experiment with this technology.
> Hal Finney
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