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If protecting workbook in ms excel (2010, 2007, 2003) is enough safe for a sensitive data? There is a possibility to choose encryption aes 128 bit in ms excel 2003 and 2007 (as default), from that what I read there is a possibility to choose aes 256 bit in ms 2010. But if I choose aes 256 bit in ms excel 2010., if I would have a possibility to open in ms excel 2007/2004? There are available some special applications to open protected Excel files, they work for sure with ms excel 2003. How it is with newer version of excel? How long should be password? 20 characters would be enough for workbooks with sensitive data?

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migrated from Jul 26 '12 at 7:56

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What do you mean by safe? You have data hidden in the workbook that you don't want the person using it to be able to get at? What exactly are you seeking to prevent from occurring? – BonyT Jul 24 '12 at 12:14

No data in excel is safe.

I can easily bypass / remove / reveal any passwords in the workbook, worksheet, or VBA level.

(for less than 100$ -last time i checked- a person can buy a commercial application that does the same thing)

If you're trying to restrict access permissions to a portion of the data, try separating the data into a secure and insecure workbooks and keeping the secure workbook in a location that only certain users can access.

And I dont think that using encryption features unique to a later version of office would make it backwords compatible... If this is something that you need to use across yoru cases, then this is something you can easily test for.. (by trying it out)

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Ok, removing the password to worksheet or workbook is quite easy (especially in newer versions), but I had in mind the password to open file. Is it really easy to braek for example 20-characters strong password with encryption AES 256 bit? Is for cracking it is used brute-force or some other method? – user1548483 Jul 25 '12 at 9:34
Yes the file level passwords are also weak. Send me a test file, I'll either prove it to you if you'd like by sending the file back without a password on it. I havn't met a password I couldn't remove form an excel file yet. But I do it rarely so it may be fun! – danielpiestrak Jul 25 '12 at 17:45

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