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UUIDv2

UUIDv2 is a DCE Security UUID — designed to include domain-specific information such as a POSIX UID or GID, along with timestamp and randomness.

It replaces part of the timestamp with a local identifier and adds a domain byte.

Generate a UUIDv2​

You can generate a UUIDv2 by specifying a domain and a local identifier:

use DomainFlow\Uuid\UuidV2;

$uuid = UuidV2::generate(1000, 'uid'); // or 'gid'
echo (string) $uuid;

Validate a UUIDv2​

UuidV2::isValid('f47ac10b-58cc-21ec-8f4c-0242ac120002');

Inspect with Inspector​

use DomainFlow\Uuid\Inspector;

$metadata = Inspector::analyze((string) $uuid)->metadata();

You’ll get:

[
  'domain' => 'POSIX UID',
  'local_identifier' => 1000,
  'note' => 'UUIDv2 replaces timestamp low bits with a UID/GID'
]

Domains​

  • 'uid': POSIX User ID
  • 'gid': POSIX Group ID

Invalid domain values (e.g. 'banana') will throw an exception.

Use Cases​

  • Secure, identity-bound UUIDs (e.g. for user-scoped sessions or audit trails)
  • Systems that require both time ordering and user context
  • DCE/RPC-based systems or applications requiring UID/GID encoding

⚠️ Note: UUIDv2 is not widely used in modern systems but is supported here for legacy or security-sensitive use cases.