Public Key Infrastructure FAQs

     Digital Certificates FAQs

•   What are digital certificates?
  
  Digital certificates are the digital equivalent (i.e. electronic format) of physical or paper certificates. Examples of physical certificates are driver's licenses, passports or membership cards. Certificates serve as identity of an individual for a certain purpose, e.g. a driver's license identifies someone who can legally drive in a particular country. Likewise, a digital certificate can be presented electronically to prove your identity or your right to access information or services on the Internet.
  

• What are the functions of a digital certificate?
  
  Typically certificates are used to generate confidence in the legitimacy of a public key. In addition to verifying a signature, verifying the signer's certificate increase the confidence of the receiver in ensuring that attempted forgery or impersonation has not occurred.

Digital certificates can be used as to verify someone's (or some company's) identity. It can be used in a variety of ways including to control access on web sites, to create virtual private networks, to secure e-mail, and to guarantee the authenticity of downloaded software.

• What are the contents of a Digital certificate?
  
  A Digital Certificate contains three elements:

Subject Name and Other Certificate Extensions

This is information about the object being certified. In the case of a person this might include one's name, nationality and email address, your organization, and the department within that organization where you work. It could also include a picture of you, a codification of your fingerprints, your passport number, and so on.

Public Key Information

This is the public key of the entity being certified. The certificate acts to bind the public key to the attribute information described above. The public key can be any asymmetric key, but is usually an RSA key.

Certifying Authority (CA) Signature

The CA signs the first two elements and thereby adds credibility to the certificate. People who receive the certificate check the signature and will believe the attribute information public key binding if they trust that certifying authority.

•  What different kinds of digital certificates are there?
  
  Digital Certificates can be categorized into Server certificates and Personal certificates. The differences lie in the information they contain and who they identify. For example, a server certificate's "Common Name" attribute is usually set to a host name or host name pattern, like www.mtnltrustline.com, while a personal certificate would have this attribute set to your full name.

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