French versions of Microsoft Office
Strong cryptographic algorithms are banned in France. So, if MS
Word or Excel document has been created (password-protected) on a computer with French regional settings, very simple
encryption algorithm (XOR-based) is being used. A 16-byte sequence is generated from
any password (we can also calculate the password from that sequence). If we
know 16 bytes from source plaintext, then password recovery is trivial. In most
cases, passwords for these files can be recovered instantly by means of statistical plaintext
analysis.
Applications for password recovery: