Excel 2013 uses a SHA-2 class, SHA512 algorithm, to calculate the hash values for sheet passwords, which cannot be cracked within a reasonable amount of time using the brute force methods applicable up to Excel 2010.Have you noticed that sheet protection VBA methods run much slower in Excel 20? That's because the new complex hashing algorithm takes longer to compute. For single sheet manual protection operations the delay is barely noticeable, but when add-ins or macros unlock/lock sheets in bulk, the delay can be significant. Office 2013 has silently introduced security changes in order to strengthen Excel protection!
