Very clever.

You really want to use symmetric encryption anyway for significant amounts
of data because public key is slooooow. Better to encrypt with a random
(relatively short) secret key, and then encrypt that with public key. That's
how TLS (SSL) does things.

Charles


-----Original Message-----
From: IBM Mainframe Discussion List [mailto:[email protected]] On
Behalf Of Phil Smith III
Sent: Sunday, August 25, 2019 6:17 PM
To: [email protected]
Subject: Re: vendor distributes their private key

CM Poncelet wrote:

>PGP allows sending encrypted emails/data to multiple recipients, where

>each recipient has a different private key, and this works AOK (but no

>idea how). 

 

Trivial: the actual payload is encrypted with a random symmetric key. Then
THAT key is encrypted with the public key of each
recipient, and the package sent contains a copy for each recipient. So in
pseudo-crypto(!), if the data is being sent to Phil,
Charles, and CM, the package contains:

 

This is for Phil: < copy of key K, encrypted with Phil's public key and
possibly sender's private key>

This is for Charles: < copy of key K, encrypted with Charles's public key
and possibly sender's private key>

This is for CM: < copy of key K, encrypted with CM's public key and possibly
sender's private key>

<payload, encrypted with key K>

 

Make sense?

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