Is this protection possible?

[DamonK]

We all know that sheets protected with passwords are never totally secure as there are a number of available password *******s for excel.

I had the thought that maybe it would be possible to have a worksheet that is not protected when saved but when it is opened there would be a sub-routine under Sub_Workbook Open that would step through each sheet and assign a random password. And when the workbook is saved it is saved without passwords again.

In this way there would be nothing for a password ******* to pick at. The only flaw I see would be that the password to open the VBA module would need to be static and this would open up the programming to change and remove. But wouldn't this be effective against most users who would only know about the utilities to open the passwords and not the programming behind excel?

Anyway that was my thought does anyone think this would be feasible and or useful?

 

[Domski]

Hi,

I'm not sure that approach would make much difference. I have a VBA procedure that will crack the password on the current active worksheet so this would mean I would be able to break whatever passwords were set when the file was open.

Dom

 

[AlexM]

If your workbook is opened when macros are disabled, passwords will not be set and all sheets will not be protected.

 

[erik.van.geit]

Hi, DamonK,
WELCOME to the BOARD!!!!!

What users do you have? Consider who you want to keep out... Real thiefs are always getting in anyway.
And what do you need to protect? Viewing data or changing them, formulas, ...

Also I see some kind of circular thinking in your post: not sure Why not just protect the normal way?

wouldn't this be effective against most users

kind regards,
Erik

 

[dave3009]

I suppose the big, big question is ...........

If the book you are trying to protect really contains such valuable information do you really want to send it anywhere?

I for one have locked down books and all you get is call after call asking you to sort something, or you get some **** who tried to adapt it themselves and buggered the lot up. Either way the dye runs in the wash, just ask folk not to adapt your formulas and if they choose not to heed your request they'll be found easily

 

[Smitty]

Welcome to the Board!

Note that this doesn't really hold water:

assign a random password

Because Excel's worksheet protection password methodology is to create a random 16-bit hash anyway, which means that the password you enter is random to begin with.

Here are a couple of good links:

http://kohei.us/2008/01/18/excel-sheet-protection-password-hash/

http://www.j-walk.com/ss/excel/faqs/protectionFAQ.htm

Probably the best note I can mirror is that passwords only keep honest people honest, like locks on doors, but they're generally good for 99% of users. If you have people breaking your stuff then it's generally a management issue from there on out.

HTH,

 

[Domski]

This topic's getting dangerously close to "how to crack a worksheet password in Excel"

 

[MagiCat]

This topic's getting dangerously close to "how to crack a worksheet password in Excel"

Unfortunately, a good discussion on how to protect a spreadsheet from hacking programs involves discussing what those programs do. For example, if I save a spreadsheet with the password "cat", it's likely to be broken by the simplest program in less than 1 second. If I use "klkeiil#$@23ACDF" then I'm safe for millions of years with some programs but I guess there are those that break the hashing system.

I have Excel 2003 (and apparently have stolen this topic but it's probably the question that the original author had). Is there a way for me to protect a sheet from prying eyes using a password (only using what Excel gives to me) as long as I'm careful to make sure that the password isn't weak (i.e. 10 characters, at least 1 number, 1 capital letter, no real words.)

 

[RoryA]

A password to open a workbook is a much harder beast to crack than one to protect a worksheet. A VBA password is possibly even weaker than a worksheet password.

 

[MagiCat]

But harder isn't necessarily what is wanted, impossible (without the computing power required to go through 19,408,409,961,765,300,000,000 different passwords) is what is needed.

What would be needed for me to create a workbook and be reasonably comfortable that even if I post it online, that it won't be cracked. That is, besides making the password have 12 characters including upper, lower, numbers, and symbols, without any words.