PhutilOpaqueEnvelopeKey.php
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	<?php

	/**
	* Holds the key for @{class:PhutilOpaqueEnvelope} in a logically distant
	* location so it will never appear in stack traces, etc. You should never need
	* to use this class directly. See @{class:PhutilOpaqueEnvelope} for
	* information about opaque envelopes.
	*
	* @task internal Internals
	*/
	final class PhutilOpaqueEnvelopeKey {

	private static $key;


	/* -( Internals )---------------------------------------------------------- */


	/**
	* @task internal
	*/
	private function __construct() {
	// <private>
	}


	/**
	* @task internal
	*/
	public static function getKey() {
	if (self::$key === null) {
	// NOTE: We're using a weak random source because cryptographic levels
	// of security aren't terribly important here and it allows us to use
	// envelopes on systems which don't have a strong random source. Notably,
	// this lets us make it to the readability check for `/dev/urandom` in
	// Phabricator on systems where we can't read it.
	self::$key = '';
	for ($ii = 0; $ii < 8; $ii++) {
	self::$key .= md5(mt_rand(), $raw_output = true);
	}
	}
	return self::$key;
	}

	}