r5806 contains the xlsx decryption. I added a new package
laz_fpspreadsheet_crypto which depends on
DCPCrypt as the main encryption/decryption engine. It will contain the dedicated units for the fpspreadsheet file formats, as wel as specialized reader/writer units which will have to do the decryption work and pass the stream to the standard reader; the same shouild happen with the writer (not available yet). The new reader/writer is registered as being user-defined, it can be selected by its ID -
sifidOOXML instead of sfOOXML.
All the file/stream reading routines of fpspreadsheet needing the format id were extended to accept an optional password. The readers in the basic package laz_fpspreadsheet ignore the password, but those in laz_fpspreadsheet_crypto have to use it to do their work.
In the directory
examples/read_write there is a new folder
ooxmldemo_crypto which contains a simple console program to read an encrypted and a protected workbook written by Excel2007 (the protected workbook is also encrypted by means of an Excel-internal password). Both files are provided, their password is "test".
The basic procedure to load an encrypted xlsx file is as follows:
- Add package laz_fpspreadsheet_crypto as a requirement to the program
- Add unit xlsxooxml_crypto to the uses clause, instead of xlsxooxml.
- In the workbook's call to ReadFromFile or ReadFromStream use the format ID sfidOOXML (instead of sfOOXML).
- In case of the file-encrypted workbook, specify the password in ReadFromStream after the format ID. No password is needed to decrypt the protected workbook. The decrypting reader accepts also normal, non-encrypted files.
As shobits1 wrote above, it must be expected that the decryption only works for files written by Excel 2007 and 2010.
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