ZyXEL Communications P-792H User Manual page 153

Tim wants to send a message to Jenny. He needs her to be sure that it comes from
1
him, and that the message content has not been altered by anyone else along the
way. Tim generates a public key pair (one public key and one private key).
Tim keeps the private key and makes the public key openly available. This means
2
that anyone who receives a message seeming to come from Tim can read it and
verify whether it is really from him or not.
Tim uses his private key to sign the message and sends it to Jenny.
3
Jenny receives the message and uses Tim's public key to verify it. Jenny knows
4
that the message is from Tim, and that although other people may have been able
to read the message, no-one can have altered it (because they cannot re-sign the
message with Tim's private key).
Additionally, Jenny uses her own private key to sign a message and Tim uses
5
Jenny's public key to verify the message.
P-792H v2 User's Guide
Chapter 11 Certificates
153