Nortel BSR222, Configuration, Page: 261 / 451

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Nortel Business Secure Router 222 Configuration — Basics
Chapter 14
Certificates
This chapter gives background information about public-key certificates and
explains how to use them.
Certificates overview
The Business Secure Router can use certificates (also called digital IDs) to
authenticate users. Certificates are based on public-private key pairs. A certificate
contains the certificate owner’s identity and public key. Certificates provide a way
to exchange public keys for use in authentication.
A Certification Authority (CA) issues certificates and guarantees the identity of
each certificate owner. There are commercial certification authorities like
CyberTrust or VeriSign and government certification authorities. You can use the
Business Secure Router to generate certification requests that contain identifying
information and public keys and then send the certification requests to a
certification authority.
In public-key encryption and decryption, each host has two keys. One key is
public and can be made openly available; the other key is private and must be kept
secure. Public-key encryption in general works as follows.
1 Tim wants to send a private message to Jenny. Tim generates a public key
pair. What is encrypted with one key can only be decrypted using the other.
2 Tim keeps the private key and makes the public key openly available.
3
Tim uses his private key to encrypt the message and sends it to Jenny.
4 Jenny receives the message and uses Tim’s public key to decrypt it.
5
Additionally, Jenny uses her own private key to encrypt a message and Tim
uses Jenny’s public key to decrypt the message.