From f8c970ec0c8548330d342f6ac7b8db000cfc0088 Mon Sep 17 00:00:00 2001
From: Ingo Schommer <ingo@silverstripe.com>
Date: Sun, 5 Dec 2010 00:19:57 +0000
Subject: [PATCH] ENHANCEMENT Added RandomGenerator for more secure CRSF tokens
 etc. (from r114497)

git-svn-id: svn://svn.silverstripe.com/silverstripe/open/modules/sapphire/branches/2.4@114499 467b73ca-7a2a-4603-9d3b-597d59a354a9
---
 security/RandomGenerator.php           | 63 ++++++++++++++++++++++++++
 tests/security/RandomGeneratorTest.php | 27 +++++++++++
 2 files changed, 90 insertions(+)
 create mode 100644 security/RandomGenerator.php
 create mode 100644 tests/security/RandomGeneratorTest.php

diff --git a/security/RandomGenerator.php b/security/RandomGenerator.php
new file mode 100644
index 000000000..4a7e4b788
--- /dev/null
+++ b/security/RandomGenerator.php
@@ -0,0 +1,63 @@
+<?php
+/**
+ * Generates entropy values based on strongest available methods
+ * (mcrypt_create_iv(), openssl_random_pseudo_bytes(), /dev/urandom, COM.CAPICOM.Utilities.1, mt_rand()).
+ * Chosen method depends on operating system and PHP version.
+ * 
+ * @package sapphire
+ * @subpackage security
+ * @author Ingo Schommer
+ */
+class RandomGenerator {
+
+	/**
+	 * @return string Returns a random series of bytes
+	 */
+	function generateEntropy() {
+		// mcrypt with urandom is only available on PHP 5.3 or newer
+		if(version_compare(PHP_VERSION, '5.3.0', '>=')) {
+			return mcrypt_create_iv(64, MCRYPT_DEV_URANDOM);
+		}
+
+		// Fall back to SSL methods - may slow down execution by a few ms
+		if (function_exists('openssl_random_pseudo_bytes')) {
+			$e = openssl_random_pseudo_bytes(64, $strong);
+			// Only return if strong algorithm was used
+			if($strong) return $e;
+		}
+
+		// Read from the unix random number generator
+		if (is_readable('/dev/urandom') && ($h = fopen('/dev/urandom', 'rb'))) {
+			$e = fread($h, 64);
+			fclose($h);
+			return $e;
+		}
+
+		// Warning: Both methods below are considered weak
+
+		// try to read from the windows RNG
+		if (class_exists('COM')) {
+			try {
+				$comObj = new COM('CAPICOM.Utilities.1');
+				$e = base64_decode($comObj->GetRandom(64, 0));
+				return $e;
+			} catch (Exception $ex) {
+			}
+		}
+
+		// Fallback to good old mt_rand()
+		return uniqid(mt_rand(), true);
+	}
+	
+	/**
+	 * Generates a hash suitable for manual session identifiers, CSRF tokens, etc.
+	 * 
+	 * @param String $algorithm Any identifier listed in hash_algos() (Default: whirlpool)
+	 *  If possible, choose a slow algorithm which complicates brute force attacks.
+	 * @return String Returned length will depend on the used $algorithm
+	 */
+	function generateHash($algorithm = 'whirlpool') {
+		return hash($algorithm, $this->generateEntropy());
+	}
+	
+}
\ No newline at end of file
diff --git a/tests/security/RandomGeneratorTest.php b/tests/security/RandomGeneratorTest.php
new file mode 100644
index 000000000..2a41ecdfa
--- /dev/null
+++ b/tests/security/RandomGeneratorTest.php
@@ -0,0 +1,27 @@
+<?php
+/**
+ * @package sapphire
+ * @subpackage tests
+ * @author Ingo Schommer
+ */
+class RandomGeneratorTest extends SapphireTest {
+
+	function testGenerateEntropy() {
+		$r = new RandomGenerator();
+		$this->assertNotNull($r->generateEntropy());
+		$this->assertNotEquals($r->generateEntropy(), $r->generateEntropy());
+	}
+	
+	function testGenerateHash() {
+		$r = new RandomGenerator();
+		$this->assertNotNull($r->generateHash());
+		$this->assertNotEquals($r->generateHash(), $r->generateHash());
+	}
+	
+	function testGenerateHashWithAlgorithm() {
+		$r = new RandomGenerator();
+		$this->assertNotNull($r->generateHash('md5'));
+		$this->assertNotEquals($r->generateHash(), $r->generateHash('md5'));
+	}
+	
+}
\ No newline at end of file