Build 3.0.0.73 of xlsgen adds support for XLSX file encryption.

3.0 RTM introduced file encryption for XLS files (i.e. binary files). This build adds the same feature for XLSX files (Excel 2007/2010/2013).

Internally, the encryption is different than with XLS files. It uses AES encryption with a 128-bit key, SHA-1 hashing and the resulting file is an OLE container with a binary blob. It is completely transparent to the user or developer.

Using the encryption is just the matter of setting a password :

workbook.EncryptionPassword = "mypassword";