Changeset 29382 for trunk/src/wp-includes/compat.php

Timestamp:

08/06/2014 05:25:03 AM (11 years ago)

Author:

nacin

Message:

Constant time for wp_verify_nonce().

File:

• trunk/src/wp-includes/compat.php (modified) (1 diff)

trunk/src/wp-includes/compat.php

@@ -95 +95 @@
     }
 }
+
+if ( ! function_exists( 'hash_equals' ) ) :
+/**
+ * Compare two strings in constant time.
+ *
+ * This function was added in PHP 5.6.
+ * It can leak the length of a string.
+ *
+ * @since 3.9.2
+ *
+ * @param string $a Expected string.
+ * @param string $b Actual string.
+ * @return bool Whether strings are equal.
+ */
+function hash_equals( $a, $b ) {
+    $a_length = strlen( $a );
+    if ( $a_length !== strlen( $b ) ) {
+        return false;
+    }
+    $result = 0;
+
+    // Do not attempt to "optimize" this.
+    for ( $i = 0; $i < $a_length; $i++ ) {
+        $result |= ord( $a[ $i ] ) ^ ord( $b[ $i ] );
+    }
+
+    return $result === 0;
+}
+endif;