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UUIDv3

UUIDv3 is a name-based, deterministic UUID that uses MD5 hashing. It generates the same UUID every time for a given name + namespace combination.

This makes it ideal for stable, repeatable identifiers across systems.

Generate a UUIDv3​

use DomainFlow\Uuid\UuidV3;

$namespace = '6ba7b810-9dad-11d1-80b4-00c04fd430c8'; // DNS namespace
$name = 'example.com';

$uuid = UuidV3::generate($namespace, $name);

Validate a UUIDv3​

UuidV3::isValid('2a444efc-3dcb-3bfb-bcd1-70d495b89b04');

Inspector Output​

use DomainFlow\Uuid\Inspector;

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

Output will include:

[
  'hash_type' => 'MD5',
  'deterministic' => true,
  'note' => 'UUIDv3 encodes a hash of namespace + name'
]

Standard Namespaces​

Some common namespaces for UUIDv3 (and v5):

  • 6ba7b810-9dad-11d1-80b4-00c04fd430c8 – DNS
  • 6ba7b811-9dad-11d1-80b4-00c04fd430c8 – URL
  • 6ba7b812-9dad-11d1-80b4-00c04fd430c8 – ISO OID
  • 6ba7b814-9dad-11d1-80b4-00c04fd430c8 – X.500 DN

Use Cases​

  • Stable, hash-based UUIDs for resource names or external identifiers
  • Avoiding collisions for known inputs (e.g. filenames, emails)
  • Deterministic UUIDs in distributed systems

⚠️ Security note: Since it uses MD5 (which is considered insecure for cryptographic purposes), avoid UUIDv3 in security-critical contexts. Use UuidV5 instead if you need stronger hashing.