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- .. _rfc4122:
- ==============
- RFC 4122 UUIDs
- ==============
- .. toctree::
- :titlesonly:
- :hidden:
- rfc4122/version1
- rfc4122/version2
- rfc4122/version3
- rfc4122/version4
- rfc4122/version5
- rfc4122/version6
- rfc4122/version7
- rfc4122/version8
- `RFC 4122`_ defines five versions of UUID, while a `new Internet-Draft under
- review`_ defines three new versions. Each version has different generation
- algorithms and properties. Which one you choose depends on your use-case. You
- can find out more about their applications on the specific page for that version.
- Version 1: Gregorian Time
- This version of UUID combines a timestamp, node value (in the form of a MAC
- address from the local computer's network interface), and a clock sequence
- to ensure uniqueness. For more details, see :doc:`rfc4122/version1`.
- Version 2: DCE Security
- This version of UUID is the same as Version 1, except the ``clock_seq_low``
- field is replaced with a *local domain* and the ``time_low`` field is
- replaced with a *local identifier*. For more details, see
- :doc:`rfc4122/version2`.
- Version 3: Name-based (MD5)
- This version of UUID hashes together a namespace and a name to create a
- deterministic UUID. The hashing algorithm used is MD5. For more details, see
- :doc:`rfc4122/version3`.
- Version 4: Random
- This version creates a UUID using truly-random or pseudo-random numbers. For
- more details, see :doc:`rfc4122/version4`.
- Version 5: Named-based (SHA-1)
- This version of UUID hashes together a namespace and a name to create a
- deterministic UUID. The hashing algorithm used is SHA-1. For more details,
- see :doc:`rfc4122/version5`.
- Version 6: Reordered Time
- This version of UUID combines the features of a
- :ref:`version 1 UUID <rfc4122.version1>` with a *monotonically increasing*
- UUID. For more details, see :ref:`rfc4122.version6`.
- Version 7: Unix Epoch Time
- This version of UUID combines a timestamp--based on milliseconds elapsed
- since the Unix Epoch--and random bytes to create a monotonically increasing,
- sortable UUID without the privacy and entropy concerns associated with
- version 1 and version 6 UUIDs. For more details, see :ref:`rfc4122.version7`.
- Version 8: Custom
- This version of UUID allows applications to generate custom identifiers in
- an RFC-compatible format. For more details, see :doc:`rfc4122/version8`.
- .. _RFC 4122: https://tools.ietf.org/html/rfc4122
- .. _new Internet-Draft under review: https://datatracker.ietf.org/doc/html/draft-ietf-uuidrev-rfc4122bis-00
|
