OOo 2.4 Calc ignore Excel read only setting

[kelvin.leung]

Hi,

Our company has a problem in using OOo 2.4 Calc. We are using both OOo 2.4 and MS Excel on Windows XP in a local network enviornment. Some user created some Excel files which had been set as read only in security tab of option as below.

If other user open this file (no matter if it is opened by another user or not), a warning will pop up and ask the user if he/she want to open this file read only. Click yes will open read only or click no will open editable. To further enhances the security, user can add password to the file. If any user needed to edit the file, they need to enter the password correctly.

However, if this file open with OOo 2.4 Calc, no such warning will come out and the file opened editable. Then user may save changes accidentally which is not suppose to be changed. Is there any method or setting that can make OOo 2.4 Calc to keep the read only setting?

Thanks
Kelvin

[jrkrideau]

This is a well-known Excel problem. Essentially Excel files are not secure at all.

I don't think that there is anything you can do about it in Calc

[Dave]

However, if this file open with OOo 2.4 Calc, no such warning will come out and the file opened editable. Then user may save changes accidentally which is not suppose to be changed. Is there any method or setting that can make OOo 2.4 Calc to keep the read only setting?

You beef is with MS. If they want security, they should provide it. Many years back, I was helping a fellow in the UK who did his spreadsheets for commercial profit. When I informed him I could open his protected Excel files using Quattro Pro at the time, he was REALLY miffed. It's an Excel problem, not an OpenOffice problem.

David.

[kelvin.leung]

I am not going to blame either OOo or MS but the incompatibility between Calc and Excel stopping companies migrating from Excel to Calc. This is because many companies already built a lot of spreadsheets on Excel. It is almost impossible to build again on Calc. This is fact.

[kelvin.leung]

I did a test on how Excel handle OOo Calc created xls protected spreadsheet and found that Excel open them editable without asking for password too. The setting gone after Excel users save the spreadsheet. It seems that we can't rely on the protection setting of both Excel and Calc because Excel ignore Calc's setting and Calc ignore Excel's. Interesting.

[Villeroy]

At a certain position within the binary file there is a certain sequence of bytes representing an encrypted password. When loading that file Excel decrypts this sequence of bytes. The user gets prompted for the password unless the encrypted one evaluates to an empty string. The file is loaded if the given password equals the decrpyted one.
The password encryption may have technical or legal pitfalls (not shure about that), so open source software can not implement the same password encryption (=encryption of the password itself rather than content encryption by password). Calc simply ignores the password and loads the file straight away. When saving xls, Calc always puts the byte sequence that stands for an empty password. I used to practice the latter in a hex-editor manually in order to rip off passwords from xls, others sold "password-crackers" for 50 bucks at that time.
As far as I know, Calc can ignore Excel passwords for opening, read-only editing and "protection" for sheets, workbook (collection of sheets) and macros.
Calc implements the protection for sheets and the collection of sheets as xml-tags, so this can be overridden easily. Tools>Protection provides little protection against casual errors.
Since 2003 they offer a similar document encryption as OOo does. OOo can not handle MSOffice encryption due to technical or legal pitfalls (again, not shure about that). Thus we can not open such documents, because the whole content is reproducable only if you decrypt it by means of the right password using the same (unknown/proprietary?) algorithm.

I don't think that Excel ignores anything in it's native file format just because some other app may have produced it. In fact it was never intended that any other software but Excel can edit that stuff. Older Excel versions simply crash when you confront it with "impossible" things, such as non-VBA macros or more than 3 conditional formats.