README

uuid-php

A small PHP class for generating RFC 9562 universally unique identifiers (UUID) from version 3 to version 8.

If all you want is a unique ID, you should call uuid4().

Implementations SHOULD utilize UUIDv7 instead of UUIDv1 and UUIDv6 if possible.

If you're regularly generating more than thousand UUIDs per second, you might want to use uuid8() instead of uuid7(). This implementation of uuid8() sacrifices some entropy compared to uuid7(), but offers 100 nanosecond granularity while being otherwise compatible.

Minimal UUID v4 implementation

Credits go to this answer on Stackoverflow for this minimal RFC 9562 compliant solution.

<?php
function uuid4()
{
    $data = random_bytes(16);
    $data[6] = chr(ord($data[6]) & 0x0f | 0x40); // set version to 0100
    $data[8] = chr(ord($data[8]) & 0x3f | 0x80); // set bits 6-7 to 10
    return vsprintf('%s%s-%s-%s-%s-%s%s%s', str_split(bin2hex($data), 4));
}

echo uuid4();

Minimal UUID v7 implementation

<?php
function uuid7()
{
    static $last_timestamp = 0;
    $unixts_ms = intval(microtime(true) * 1000);
    if ($last_timestamp >= $unixts_ms) {
        $unixts_ms = $last_timestamp + 1;
    }
    $last_timestamp = $unixts_ms;
    $data = random_bytes(10);
    $data[0] = chr((ord($data[0]) & 0x0f) | 0x70); // set version
    $data[2] = chr((ord($data[2]) & 0x3f) | 0x80); // set variant
    return vsprintf(
        '%s%s-%s-%s-%s-%s%s%s',
        str_split(
            str_pad(dechex($unixts_ms), 12, '0', \STR_PAD_LEFT) .
                bin2hex($data),
            4
        )
    );
}

echo uuid7();

Installation

If you need comparison tools or sortable identifiers like in versions 6, 7, and 8, you might find this small and fast package useful. It doesn't require any other dependencies.

composer require oittaa/uuid

Usage

How to generate

<?php

require 'vendor/autoload.php';

use UUID\UUID;

// Generate a version 3 (name-based and hashed with MD5) UUID
// Namespaces: NAMESPACE_DNS, NAMESPACE_URL, NAMESPACE_OID, NAMESPACE_X500
$uuid3 = UUID::uuid3(UUID::NAMESPACE_DNS, 'php.net');
echo $uuid3 . "\n"; // 11a38b9a-b3da-360f-9353-a5a725514269

// Generate a version 4 (random) UUID
$uuid4 = UUID::uuid4();
echo $uuid4 . "\n"; // e.g. 2140a926-4a47-465c-b622-4571ad9bb378

// Generate a version 5 (name-based and hashed with SHA1) UUID
$uuid5 = UUID::uuid5(UUID::NAMESPACE_DNS, 'php.net');
echo $uuid5 . "\n"; // c4a760a8-dbcf-5254-a0d9-6a4474bd1b62

// Generate a version 6 (lexicographically sortable) UUID
$uuid6_first = UUID::uuid6();
echo $uuid6_first . "\n"; // e.g. 1ec9414c-232a-6b00-b3c8-9e6bdeced846
$uuid6_second = UUID::uuid6();
var_dump($uuid6_first < $uuid6_second); // bool(true)

// Generate a version 7 (lexicographically sortable) UUID
$uuid7_first = UUID::uuid7();
echo $uuid7_first . "\n"; // e.g. 017f22e2-79b0-7cc3-98c4-dc0c0c07398f
$uuid7_second = UUID::uuid7();
var_dump($uuid7_first < $uuid7_second); // bool(true)

// Generate a version 8 (lexicographically sortable) UUID
$uuid8_first = UUID::uuid8();
echo $uuid8_first . "\n"; // e.g. 017f22e2-79b0-8cc3-98c4-dc0c0c07398f
$uuid8_second = UUID::uuid8();
var_dump($uuid8_first < $uuid8_second); // bool(true)

Tools

<?php

require 'vendor/autoload.php';

use UUID\UUID;

// Test if a given string is a valid UUID
$isvalid = UUID::isValid('11a38b9a-b3da-360f-9353-a5a725514269');
var_dump($isvalid); // bool(true)

// The string standard representation of the UUID.
$tostring = UUID::toString('{C4A760A8-DBCF-5254-A0D9-6A4474BD1B62}');
var_dump($tostring); // string(36) "c4a760a8-dbcf-5254-a0d9-6a4474bd1b62"

// Test if two UUIDs are equal
$equals1 = UUID::equals(
    'c4a760a8-dbcf-5254-a0d9-6a4474bd1b62',
    '2140a926-4a47-465c-b622-4571ad9bb378'
);
var_dump($equals1); // bool(false)

$equals2 = UUID::equals(
    'c4a760a8-dbcf-5254-a0d9-6a4474bd1b62',
    'C4A760A8-DBCF-5254-A0D9-6A4474BD1B62'
);
var_dump($equals2); // bool(true)

$equals3 = UUID::equals(
    'urn:uuid:c4a760a8-dbcf-5254-a0d9-6a4474bd1b62',
    '{C4A760A8-DBCF-5254-A0D9-6A4474BD1B62}'
);
var_dump($equals3); // bool(true)

// UUID comparison. Returns < 0 if uuid1 is less than uuid2;
// > 0 if uuid1 is greater than uuid2, and 0 if they are equal.
$cmp1 = UUID::cmp(
    '11a38b9a-b3da-360f-9353-a5a725514269',
    '2140a926-4a47-465c-b622-4571ad9bb378'
);
var_dump($cmp1 < 0); // bool(true)

$cmp2 = UUID::cmp(
    'c4a760a8-dbcf-5254-a0d9-6a4474bd1b62',
    '2140a926-4a47-465c-b622-4571ad9bb378'
);
var_dump($cmp2 > 0); // bool(true)

$cmp3 = UUID::cmp(
    'urn:uuid:c4a760a8-dbcf-5254-a0d9-6a4474bd1b62',
    '{C4A760A8-DBCF-5254-A0D9-6A4474BD1B62}'
);
var_dump($cmp3 === 0); // bool(true)

// Extract Unix time from versions 6, 7, and 8 as a string.
$uuid6_time = UUID::getTime('1ec9414c-232a-6b00-b3c8-9e6bdeced846');
var_dump($uuid6_time); // string(18) "1645557742.0000000"
$uuid7_time = UUID::getTime('017f22e2-79b0-7cc3-98c4-dc0c0c07398f');
var_dump($uuid7_time); // string(18) "1645557742.0000000"
$uuid8_time = UUID::getTime('017f22e2-79b0-8cc3-98c4-dc0c0c07398f');
var_dump($uuid8_time); // string(18) "1645557742.0007977"

// Extract the UUID version.
$uuid_version = UUID::getVersion('2140a926-4a47-465c-b622-4571ad9bb378');
var_dump($uuid_version); // int(4)

UUIDv6 Field and Bit Layout

        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |                           time_high                           |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |           time_mid            |      time_low_and_version     |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |clk_seq_hi_res |  clk_seq_low  |         node (0-1)            |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |                         node (2-5)                            |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

UUIDv7 Field and Bit Layout

        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |                           unix_ts_ms                          |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |          unix_ts_ms           |  ver  |       rand_a          |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |var|                        rand_b                             |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |                            rand_b                             |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

UUIDv8 Field and Bit Layout

        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |                           unix_ts_ms                          |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |          unix_ts_ms           |  ver  |       subsec          |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |var|sub|                     rand                              |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
        |                             rand                              |
        +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

• unix_ts_ms: 48 bit big-endian unsigned number of Unix epoch timestamp with millisecond level of precision
• ver: The 4 bit UUIDv8 version (1000)
• subsec: 12 bits allocated to sub-second precision values
• var: 2 bit UUID variant (10)
• sub: 2 bits allocated to sub-second precision values
• rand: The remaining 60 bits are filled with pseudo-random data

14 bits dedicated to sub-second precision provide 100 nanosecond resolution. The unix_ts_ms and subsec fields guarantee the order of UUIDs generated within the same timestamp by monotonically incrementing the timer.