MWCryptRand.php
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MWCryptRand.php
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	<?php
	/**
	* @license GPL-2.0-or-later
	* @author Daniel Friesen
	*/

	/**
	* A cryptographic random generator class used for generating secret keys
	*
	* This is based in part on Drupal code as well as what we used in our own code
	* prior to introduction of this class.
	*/
	class MWCryptRand {

	/**
	* Generate a run of cryptographically random data and return
	* it in hexadecimal string format.
	*
	* @param int $chars The number of hex chars of random data to generate
	* @return string Hexadecimal random data
	*/
	public static function generateHex( $chars ) {
	// hex strings are 2x the length of raw binary so we divide the length in half
	// odd numbers will result in a .5 that leads the generate() being 1 character
	// short, so we use ceil() to ensure that we always have enough bytes
	$bytes = ceil( $chars / 2 );
	// Generate the data and then convert it to a hex string
	$hex = bin2hex( random_bytes( $bytes ) );

	// A bit of paranoia here, the caller asked for a specific length of string
	// here, and it's possible (eg when given an odd number) that we may actually
	// have at least 1 char more than they asked for. Just in case they made this
	// call intending to insert it into a database that does truncation we don't
	// want to give them too much and end up with their database and their live
	// code having two different values because part of what we gave them is truncated
	// hence, we strip out any run of characters longer than what we were asked for.
	return substr( $hex, 0, $chars );
	}
	}