question re practical use of secret sharing

[Geoffrey Hird]

Peter Gutmann writes:

> >Is anyone aware of a commercial product that implements 
> >secret sharing? If so, can I get a pointer to some product
> >literature?
> 
> It's available as part of other products (e.g. nCipher do it 
> for keying their HSMs)

Do you mean the "k of n" operator cards?  For those, I don't
think nCipher is using real secret sharing.  I would guess
that the HSM knows the secret(s), and counts the operator
cards that are submitted.

There is a financial standard for distributing ZCMK's (Zone
Control Master Keys) that splits the ZCMK up into three
pieces the same length as the original.  This is "3 of 3".
nCipher and other HSM vendors support this, and it's used
wtih a little hand-held PIN pad.  I guess this would count
as an example of products that use secret sharing.  Perhaps
this is what you were referring to.

gh  

> -----Original Message-----
> From: owner-cryptography at metzdowd.com 
> [mailto:owner-cryptography at metzdowd.com] On Behalf Of Peter Gutmann
> Sent: Thursday, June 21, 2007 6:57 AM
> To: cljt1 at jacksons.net; cryptography at metzdowd.com
> Subject: Re: question re practical use of secret sharing
> 
> "Charles Jackson" <cljt1 at jacksons.net> writes:
> 
> >Is anyone aware of a commercial product that implements 
> secret sharing? If
> >so, can I get a pointer to some product literature?
> 
> It's available as part of other products (e.g. nCipher do it 
> for keying their
> HSMs), but I don't know of any product that just does... 
> secret sharing.  What
> would be the user interface for such an application?  What 
> would be the target
> audience?  (I mean a real target audience, not some 
> hypothesised scenario).
> 
> (This is actually a serious question.  I talked with some 
> crypto guys a few
> years ago about doing a standard for secret sharing, but to 
> do that we had to
> come up with some general usage model for it rather than just 
> one particular
> application-specific solution, and couldn't).
> 
> Besides that, user demand for it was practically 
> nonexistent... no, it was
> completely nonexistent, apart from a few highly specialised 
> custom uses we
> couldn't even find someone to use as a guinea pig for testing, and the
> existing specialised users already had specialised solutions 
> of their own
> for handling it.
> 
> Peter.
> 
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