A Certificate Authority (CA) is an entity which is trusted to validate and certify the identities of others. In reality a CA is a company which maintains a software package that can manage the requests, issuance and revocation of certificate files. A CA is created by installing a certificate management software package such as Microsoft Certificate Services and implementing policies to identify and issue certificates to requestors. Certificate issuance policies fall into two general categories.
Software Issuance Policies – These policies use some form of existing credential to issue a certificate. In some cases this may be as simple as validating that your email address is in fact your email address as in the case of Thwarte (www.thwarte.com). In other cases you must have a trusted network credential. This is the method used by Active Directory integrated CAs. These CAs are referred to as enterprise CAs. Enterprise CAs will be discussed in more detail in a future article.
Manual Issuance Policies – These policies involve non-technical verification of identity and may include methods such as notarized letters, photo IDs or in some cases fingerprinting. These are generally only found in highly secure environments such as those found in large companies or the government.