On Jul 7, 2004, at 2:19 PM, Marta Edie wrote:

> What is "if you like" ? I thought Lee told me to delete them. They 
> kept multiplying, so i took a good look at the long line of what I 
> considered duplicates and did a "delete" job.

I don't think I meant you should delete them, only that there's no harm 
in deleting them. Here's what they are.

The idea behind public key encryption is that every user is issued two 
keys: a public key and a private key. The public key is distributed for 
everyone to read. The private key is kept secret.

When you receive a signed message, it contains a digital signature 
that's derived from the content of the message and the private key of 
the sender. Using the public key of the sender and some tricky 
mathematics, the signature can be verified as having been generated 
using the sender's private key. It also verifies that the content of 
the message has not been changed. (But, the private key cannot be 
determined in the process.)

What you are seeing in your keychain are the public keys of the 
senders. Your mail program gets them from the company that issued the 
keys. In this case, that's Thawte, based in South Africa.

Here's another way to think of it. Users are given two keys because 
anything locked with one of the keys can only be unlocked with the 
other. One of the keys is kept secret and the other is made public. A 
message locked with your public key can only be unlocked with your 
private key and a message locked with your private key can only be 
unlocked with your public key.



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