RFC 1439 (rfc1439) - Page 1 of 11

The Uniqueness of Unique Identifiers

Network Working Group                                         C. Finseth
Request for Comments: 1439                       University of Minnesota
                                                              March 1993


                  The Uniqueness of Unique Identifiers

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard.  Distribution of this memo is
   unlimited.

Abstract

   This RFC provides information that may be useful when selecting a
   method to use for assigning unique identifiers to people.

1. The Issue

   Computer systems require a way to identify the people associated with
   them.  These identifiers have been called "user names" or "account
   names."  The identifers are typically short, alphanumeric strings.
   In general, these identifiers must be unique.

   The uniqueness is usually achieved in one of three ways:

   1) The identifiers are assigned in a unique manner without using
   information associated with the individual.  Example identifiers are:

           ax54tv
           cs00034

   This method was often used by large timesharing systems.  While it
   achieved the uniqueness property, there was no way of guessing the
   identifier without knowing it through other means.

   2) The identifiers are assigned in a unique manner where the bulk of
   the identifier is algorithmically derived from the individual's name.
   Example identifers are:

           Craig.A.Finseth-1
           Finseth1
           caf-1
           fins0001

   3) The identifiers are in general not assigned in a unique manner:
   the identifier is algorithmically derived from the individual's name



Finseth