Comment 17 for bug 192056

(In reply to comment #3)
> Coming back to this - Rodo, on your radar? Kohei, any pointers - we do that for
> xlsx already, do we?

We only do AES 128 for xlsx, which Excel 2007 uses by default. It generally works, but occasionally fails (there are several bug reports for this).

AFAIK we support RC4 only for the binary i.e. xls.

MSCodec_Std97 in filter does the RC4 encryption, both for encryption and decryption. We use that for the binary xls encryption support. I'm not sure about Writer's support for encrypted doc, but it probably uses this class too.