Compaq Evo n800c Wireless Security - Page 15

Wireless Security White Paper 15 Digital Certificates Digital certificates are electronic files that can be used as unique identifiers for people and resources over networks. A digital certificate binds a user's identity to a public key, thus establishing trust. Digital certificates can also be used to help secure confidential communication between two parties. A certificate typically includes the following information relating to its owner and to the Certificate Authority (CA) that issued it: • The name of the holder and other uniquely identifying detail such as the URL of the Web server using the certificate and the holder's e-mail address • The holder's public key, which can be used to encrypt sensitive information for the certificate holder • The name of the Certification Authority (CA) that issued the certificate • A serial number • The validity period (or lifetime) of the certificate (a start and end date) When the issuing CA creates the certificate, it digitally signs the information on the certificate. The CA's signature on the certificate is like a tamper-detection seal; any tampering with the contents is easily detected. Figure 7 illustrates digital certificates. What's in a certificate? Subject DN: cn=Bob Smith, o=ACME, c=US Serial #: 8391037 Start:1/5/97 1:02 End:7/5/98 1:02 CRL:cn=CRL2, o=ACME, c=US SubjectAltName: IP, DNS, email Key: CA DN: o=ACME, c=US Unique name of owner Unique serial number Period of validity Revocation information Alternate Subject identifiers Public key CA's digital signature Name of issuing CA Figure 7: Digital Certificates