Add hex string generator based on random_bytes()

src/Vision/Random/String.php

@@ -0,0 +1,30 @@
+<?php
+/**
+ * Vision PHP-Framework
+ *
+ * @author Frank Liepert <[email protected]>
+ * @copyright 2012-2015 Frank Liepert
+ * @license http://www.opensource.org/licenses/mit-license.php MIT
+ */
+namespace Vision\Random;
+
+class String
+{
+    /**
+     * @param int $length
+     *
+     * @return bool|string
+     */
+    public function generateHex($length)
+    {
+        $length = (int) $length;
+
+        if ($length < 2 || (($length % 2) === 1)) {
+            return false;
+        }
+
+        $bytes = random_bytes($length / 2);
+
+        return $bytes ? bin2hex($bytes) : false;
+    }
+}

tests/Random/StringTest.php

@@ -0,0 +1,28 @@
+<?php
+namespace VisionTest\Random;
+
+use Vision\Random\String;
+
+class StringTest extends \PHPUnit_Framework_TestCase
+{
+    public function testGenerateHex()
+    {
+        $string = new String();
+
+        $hex = $string->generateHex(10);
+        $this->assertInternalType('string', $hex);
+        $this->assertSame(10, strlen($hex));
+        $this->assertTrue(ctype_xdigit($hex));
+    }
+
+    public function testGenerateHexWithInvalidLength()
+    {
+        $string = new String();
+
+        $hex = $string->generateHex(3);
+        $this->assertFalse($hex);
+
+        $hex = $string->generateHex(1);
+        $this->assertFalse($hex);
+    }
+}