Why do we need Certification Services?
Most network technologies and applications have requirements for authenticity and privacy, and have provisions for this.
Examples include WWW transactions, e-mail, directories (DNS, X.500), file-transfer, remote login, EDI, legal transactions, electronic money, secure IP
They use encryption techniques for authenticity and confidentiality rather than uid/password mechnisms, in particular public key encryption systems for digital signatures.
Public key encryption requires public keys to be authenticated.