The Uniqueness of Unique Identifiers (RFC1439)
Original Publication Date: 1993-Mar-01
Included in the Prior Art Database: 2019-Feb-10
Internet Society Requests For Comment (RFCs)
This RFC provides information that may be useful when selecting a method to use for assigning unique identifiers to people. This memo provides information for the Internet community. It does not specify an Internet standard.
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.
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:
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 [Page 1]
RFC 1439 Uniqueness of Unique Identifiers March 1993
and duplicates are handled in an ad-hoc manner. Example identifiers are:
Now that we have widespread electronic mail, an important feature of an identifier system is the ability to predict the identifier based on other information associated with the individual. This other information is typically the person’s name.
Methods two and three make such predictions possible, especially if you have one example mapping from a person’s name to the identifier. Method two relies on using some or all of the name and algorithmically varying it to ensure uniqueness (for example, by appending an integer). Method three relies on using some or all of the name and selects an alternate identifier in the case of a duplication.
For both methods, it is important to minimize the need for making the adjustments required to ensure uniqueness (i.e., an integer that is not 1 or an alternate identifier). The probability that an adjustment will be required depends on the format of the identifer and the size of the organization.
2. Identifier Formats
There are a number of popular identifier formats. This section will list some of them and supply both typical and maximum values for the number of possible identifiers. A "typical" value is the number that you are likely to run into in real life. A "maximum" value is the largest number of possible (without getting extreme about it) values. All ranges are expressed as a number of bits.
There are three popular formats based on initials: t...