From: "Perry E. Metzger" <perry@imsi.com>
Date: Fri, 3 Jun 94 10:12:16 PDT
To: bill.stewart@pleasantonca.ncr.com   +1-510-484-6204)
Subject: Re: Faster way to deescrow Clipper
In-Reply-To: <9406031703.AA23517@anchor.ho.att.com>
Message-ID: <9406031712.AA04494@snark.imsi.com>
MIME-Version: 1.0
Content-Type: text/plain



bill.stewart@pleasantonca.ncr.com +1-510-484-6204 says:
> We don't know where in the LEAF the chipid is, but if they
> use a fixed format and don't do a key-dependent permutation of the LEAF bits,
> it shouldn't be hard to figure out (unless the checksum comes first
> and they use a block-chaining encryption, in which case you know you lose.)
> 
> That would let you create rogue LEAFs with known users' chipids,
> which would be interesting -

The defect in this notion that the LEAF is encrypted with the family
key, which is not public knowledge. The mode that this encryption is
performed in is not public knowledge, either.

Perry