From: drzaphod@brewmeister.xstablu.com (DrZaphod)
Date: Wed, 26 Jan 94 21:22:12 PST
To: mmarkley@microsoft.com (Mike Markley)
Subject: Re: Multikey crypto
In-Reply-To: <9401270136.AA13570@netmail2.microsoft.com>
Message-ID: <m0pPP6Z-0003DXC@brewmeister.xstablu.com>
MIME-Version: 1.0
Content-Type: text/plain


> Has anyone ever done anything with an encryption scheme that allows 
> multiple unlocking keys? What I'm thinking about is a way to encrypt 
> some data and then create multiple keys that will decrypt the data. I 
> want to be able to encrypt a document and then give multiple people 
> access to the document and be able to lock out a key and/or generate 
> new keys without having to redistribute keys to everybody that already 
> has one.
--> Mike Markley             

	I was thinking about this the other day.. and my first reaction
was the following.

	What if you encrypted the document with p/k and made multiple
copies of the same [private] key.  Then you encrypted each copy of the
key with a user's public key.  Now each user has a copy of the private key.
If you decide Joe SHOULDN'T have access to the data anymore, you can
re-encrypt the document and redistribute the p/k encrypted copies of the
key.  There may be some fancy algorithms to achieve more security.. and
ease of use.. but that's the answer I came up with.  TTFN!
  

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