Add method to generate secure random strings.

src/Utility/Security.php

@@ -133,6 +133,18 @@ public static function randomBytes($length)
         return $bytes;
     }
 
+    /**
+     * Creates a secure random string.
+     *
+     * @param int $length String length
+     * @return string
+     * @since 3.6.0
+     */
+    public static function randomString($length)
+    {
+        return bin2hex(Security::randomBytes($length / 2));
+    }
+
     /**
      * Like randomBytes() above, but not cryptographically secure.
      *

tests/TestCase/Utility/SecurityTest.php

@@ -334,6 +334,22 @@ public function testRandomBytes()
         $this->assertRegExp('/[^0-9a-f]/', $value, 'should return a binary string');
     }
 
+    /**
+     * Test the randomString method.
+     *
+     * @return void
+     */
+    public function testRandomString()
+    {
+        $value = Security::randomString(16);
+        $this->assertSame(16, strlen($value));
+
+        $value = Security::randomString(64);
+        $this->assertSame(64, strlen($value));
+
+        $this->assertRegExp('/^[0-9a-f]+$/', $value, 'should return a ASCII string');
+    }
+
     /**
      * Test the insecureRandomBytes method
      *