UUIDs (Universally Unique Identifiers) are defined and specified in several RFCs (Request for Comments) that address different aspects and versions of UUIDs. Below is a summary of the key RFCs related to UUIDs:
1. RFC 4122 - A Universally Unique Identifier (UUID) URN Namespace
- Title: A Universally Unique Identifier (UUID) URN Namespace
- Description: RFC 4122 defines the structure, format, and algorithms for UUIDs, including multiple versions like UUIDv1 (time-based), UUIDv3 (name-based using MD5), UUIDv4 (random), and UUIDv5 (name-based using SHA-1). This RFC outlines how UUIDs should be generated and formatted to ensure uniqueness across systems and time.
- Link: RFC 4122
2. RFC 4122 - Revised UUID Specification
- Title: A Universally Unique Identifier (UUID) URN Namespace
- Description: This RFC includes an updated and revised specification for UUIDs, addressing some issues from the original UUID specification and clarifying various aspects of UUID generation and usage.
- Link: RFC 4122
3. RFC 7484 - The UUID Format
- Title: The UUID Format
- Description: RFC 7484 updates the specifications for UUIDs to reflect modern usage and ensure consistency in implementations. This RFC details the standard UUID format and includes clarifications on its application.
- Link: RFC 7484
4. RFC 7590 - URNs for Universally Unique Identifiers
- Title: URNs for Universally Unique Identifiers
- Description: This RFC specifies a Uniform Resource Name (URN) namespace for UUIDs, providing a standardized way to refer to UUIDs in a URN format.
- Link: RFC 7590
5. RFC 4211 - Universal Unique Identifier (UUID) Format and Representation
- Title: Universal Unique Identifier (UUID) Format and Representation
- Description: RFC 4211 defines the format and representation for UUIDs, focusing on ensuring compatibility and consistency across different systems and applications.
- Link: RFC 4211
6. RFC 7540 - Hypertext Transfer Protocol Version 2 (HTTP/2)
- Title: Hypertext Transfer Protocol Version 2 (HTTP/2)
- Description: While not specifically about UUIDs, RFC 7540 specifies the HTTP/2 protocol, which can use UUIDs in various contexts such as headers or identifiers within HTTP requests and responses.
- Link: RFC 7540
7. RFC 7490 - The IETF OAuth 2.0 Authorization Framework: JWT Bearer Token Profiles
- Title: The IETF OAuth 2.0 Authorization Framework: JWT Bearer Token Profiles
- Description: This RFC defines the use of JWT (JSON Web Tokens) for OAuth 2.0, which often includes UUIDs or similar unique identifiers for tokens.
- Link: RFC 7490
Summary
These RFCs collectively define the standards and practices for generating, using, and representing UUIDs. They ensure that UUIDs can be reliably and consistently used across different systems and applications to uniquely identify entities.
For the most authoritative and up-to-date information on UUIDs, RFC 4122 remains the primary reference, as it provides the most comprehensive specification for UUID formats and generation algorithms.