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ParagonIE_Sodium_Compat::randombytes_buf( int $numBytes ): string

Source
wp-includes/sodium_compat/src/Compat.php:4048
Generate a string of bytes from the kernel's CSPRNG.

Description

Proudly uses /dev/urandom (if getrandom(2) is not available).

Compatibility

WordPress
core
PHP
7.4–8.6-dev
  • 6.7.7
  • 6.8.8
  • 6.9.7
  • 7.0.4
  • 7.1.0

Present in every tracked release (6.7.7 to 7.1.0), and compiles on PHP 7.4 through 8.6-dev.

Parameters

$numBytesint

Return value

string

Performance profile

How much work a call to ParagonIE_Sodium_Compat::randombytes_buf() does, and what it touches: the algorithmic scaling, the Zend instruction count per call across PHP versions, the hooks it hands control to, and the core code that calls it. Measured from the compiled opcodes, not a stopwatch, so every number is identical on any machine running the same PHP version, and every function in core is ranked by cost.

Cost class
Trivial

Touches nothing outside its own arguments.

Scaling
Constant

No loop in the body: the same number of instructions runs whatever you pass in.

Instructions
12–18

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 34.

Plugin surface
None

Nothing here hands control to plugin code.

Called by
5

5 places in core call this, so the cost is paid more often than your own code shows.

What one call costs · 4 distinct outcomes

One number would be a lie: the work depends on which branch runs. These are every distinct cost ParagonIE_Sodium_Compat::randombytes_buf() can have, taken from its control-flow graph on PHP 8.5.

WhenInstructionsCalls it makes
!is_int($numBytes) && !$numBytes12none
::use_fallback()12–17::use_fallback(), call_user_func()
!::use_fallback() && $numBytes13–18::use_fallback()
!::use_fallback() && !$numBytes13–18::use_fallback(), random_bytes()

Across PHP versions

PHPCompiledExecutedBranchesNotes
8.6-dev3412–184
8.53412–184
8.43412–1842 fewer instructions than PHP 8.3
8.33612–204
8.23612–204
8.13612–204
7.43612–204

An instruction is not a fixed amount of time, so a matching count is not necessarily the same speed; what it rules out is a difference in the work itself.

Uses · 3

  • TypeError::__construct()
  • ParagonIE_Sodium_Compat::use_fallback()Should we use the libsodium core function instead? This is always a good idea, if it's available. (Unless we're in the middle of running our unit test suite.)
  • SodiumException::__construct()

Used by · 5

Source code

    public static function randombytes_buf($numBytes)    {        /* Type checks: */        if (!is_int($numBytes)) {            if (is_numeric($numBytes)) {                $numBytes = (int) $numBytes;            } else {                throw new TypeError(                    'Argument 1 must be an integer, ' . gettype($numBytes) . ' given.'                );            }        }        /** @var positive-int $numBytes */        if (self::use_fallback('randombytes_buf')) {            return (string) call_user_func('\\Sodium\\randombytes_buf', $numBytes);        }        if ($numBytes < 0) {            throw new SodiumException("Number of bytes must be a positive integer");        }        return random_bytes($numBytes);    }

Changelog

Unchanged from 6.7.7 through 7.1.0.

  1. 6.7.7
  2. 6.8.8
  3. 6.9.7
  4. 7.0.4
  5. 7.1.0

Signature, return type and hooks compared across 5 parsed releases.

About this page

Parsed data
Generated from the wordpress-develop 7.1.0 tag, from src/wp-includes/sodium_compat/src/Compat.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.
Corrections
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