This feature request is already logged number of times here. The 2003 format was comparatively easy to encrypt and decrypt, similar to Microsoft Project (MSP). However later versions contained complex logic and as it is not an open specification, so there are lot of issues in reading/writing the password protected files. Lot of effort is put to resolve this issue but still no success. This issue is postponed and may not be resolved in the near future. Once resolved, it will be announced in our blogs. Please feel free to write us again for further assistance.
This is to inform you that saving a password protected file is not supported yet. However, you may read the password protected document using the following code sample: