From: jim@bilbo.suite.com (Jim Miller)
Date: Wed, 1 Jun 94 11:37:45 PDT
To: cypherpunks@toad.com
Subject: Re: Clipper in patent trouble?
Message-ID: <9406011835.AA28181@bilbo.suite.com>
MIME-Version: 1.0
Content-Type: text/plain



smb@research.att.com writes:

> Btw -- I found the patent online via WWW; see http://town.hall.org/
> and do the obvious.  If you want just that single patent, go to
> ftp://ftp.town.hall.org/patent/data1/05276/05276737, or do the obvious
> ftp.
> 



Following smb's suggestion, I WWW'ed to town.hall.org and started poking  
around.  I found a second Micali "fair crypto-system" patent that also  
looks like it would cover Clipper.  It is patent number 05315658 (the  
other was 05276737).

I found it by traversing to

http://town.hall.org/cgi-bin/srch-patent

and searching using "public key" as the search criteria.

The two patents seem vary similar, but it seems to me that the second  
patent more closely describes a system similar to Clipper:

-----

NUM     Claim Number:				7.

Claim 7

     7. A method, using a cryptosystem, for enabling a predetermined  
entity to monitor communications of users suspected of unlawful activities  
while protecting the privacy of law-abiding users, wherein one user has at  
least a secret decryption key, comprising the steps of:

 having trustees hold pieces of information that are guaranteed to include
  shares of a secret decryption key; and

 upon a predetermined request, having a given number of trustees each  
reveal the piece of information that includes the share of the secret  
decryption key to enable the entity to attempt to monitor communications  
to the user suspected of unlawful activities.

NUM     Claim Number:				8.

     8. The method as described in claim 7 wherein upon the predetermined
request all of the trustees each reveal the piece of information.

[..]

NUM     Claim Number:				12.

     12. A method, using a cryptosystem, for enabling a predetermined  
entity to confirm that users of a system exchange messages encrypted  
according to a predetermined algorithm, comprising the steps of:

 providing each user in the system with a secure chip containing at least
  one secret key unknown to the user; and

 having the user send encrypted messages using the secure chip; and

 with each encrypted message sent by a user, having the secure chip also
  send a data string, computed using the secret key, to guarantee the  
entity that the encrypted message was generated by the secure chip using  
the predetermined algorithm.

NUM     Claim Number:				13.

     13. The method as described in claim 12 further including the steps  
of:

 providing trustees with pieces of information including shares of a  
secret key; and

 upon a predetermined request, having a given number of trustees send
  information including shares of the secret key to allow the entity to
  monitor communications to a suspect user.


 Jim_Miller@suite.com