So far our description is similar to how a facility for locating the address (in- stead of certificate), for a certain machine or person on the Internet, would work. The facility that implements this in today’s world is called the Domain Name Sys- tem (DNS). Our description also resembles the directory service , and its more successful Internet protocol implementation which is called the Lightweight Directory Access Protocol (LDAP). This thesis compare the Domain Name System and the Lightweight Directory Access Protocol for use as a certificate lookup service. In particular we focus on the application of secure electronic mail, used to send messages between persons using the Internet
