Index: src/OFSecureData.h
==================================================================
--- src/OFSecureData.h
+++ src/OFSecureData.h
@@ -89,10 +89,21 @@
  * @return An initialized OFSecureData
  */
 - (instancetype)initWithItemSize: (size_t)itemSize
 			   count: (size_t)count;
 
+/*!
+ * @brief Checks the OFSecureData for equality to another object.
+ *
+ * If the specified object is a subclass of @ref OFData, the comparison is
+ * performed in constant time.
+ *
+ * @param object The object which should be tested for equality
+ * @return A boolean whether the OFSecureData is equal to the specified object
+ */
+- (bool)isEqual: (nullable id)object;
+
 /*!
  * @brief Zeroes the data.
  */
 - (void)zero;
 

Index: src/OFSecureData.m
==================================================================
--- src/OFSecureData.m
+++ src/OFSecureData.m
@@ -454,10 +454,31 @@
 {
 	return [[OFSecureData alloc] initWithItems: _items
 					  itemSize: _itemSize
 					     count: _count];
 }
+
+- (bool)isEqual: (id)object
+{
+	OFData *otherData;
+	unsigned char diff;
+
+	if (![object isKindOfClass: [OFData class]])
+		return false;
+
+	otherData = object;
+
+	if (otherData->_count != _count || otherData->_itemSize != _itemSize)
+		return false;
+
+	diff = 0;
+
+	for (size_t i = 0; i < _count * _itemSize; i++)
+		diff |= otherData->_items[i] ^ _items[i];
+
+	return (diff == 0);
+}
 
 - (OFString *)description
 {
 	return @"<OFSecureData>";
 }