[citation needed] Office 2010 employed AES and a 128-bit key, but the number of SHA-1 conversions doubled to 100,000.
[6] It introduces SHA-512 hashes in the encryption algorithm, making brute-force and rainbow table attacks slower.
[citation needed] Office 2016 uses, by default, 256-bit AES, the SHA-2 hash algorithm, 16 bytes of salt and CBC (cipher block chaining).
Attacks can be sped up through multiple CPUs, also in the cloud, and GPGPU (applicable only to Office 2007-10 documents).
[citation needed] The protection for worksheets and macros is necessarily weaker than that for the entire workbook, as the software itself must be able to display or use them.