What is this kind of crypto called?

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>
> On 4/4/06, Craig Brooksby <rcbrxb at gmail.com> wrote:
> > I once read of a python library for creating a certain type of
> > cryptography.  I've forgotten the keyword for this kind of crypto and
> > so I can't find it!
> >
> > What I'm talking about:  You encrypt a file, and generate three keys,
> > and give a key to each of three people.  No single key can open the
> > file.  It requires *any two* of the three keys to open it.
> >
> > What's the term for this?  Not "federated?"  Is "escrow" in there
> > somewhere?  Can one of you crypto-spook types help me name what I'm
> > looking for?
> >
> > ---------------------------------------------------

Sounds kind of like Diffie-Hellman (http://en.wikipedia.org/wiki/Diffie_Hellman)

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