Formula obfuscation calc

asked 2015-08-10 22:35:34 +0100

gareins gravatar image

At present there isn't any solid formula locking method in calc (neither is it in Excel). Using classic password locks is easily crackable with dedicated software. Still, there are people interested in having their formulas hidden more robustly from recipient of that sheet file.

I think implementing "formula hiding feature", that would perform some algebra on formulas, to create longer and stranger formulas, would be useful. This kind of thing algorithm should be randomized, so that different randomness would generate different formulas from one input formula.

Deobfuscation would surely be possible, but nobody could ever guarantee, that their software can produce original formulas, since there are multiple input formulas, that would generate that obfuscated formulas.

If this idea is old, stupid or impossible, I am sorry for wasting reader's time :)

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I would be interested in the names of "dedicated software" and how it works. If it cracks by brute-force, using longer passwords or passwords with rare Unicode characters is a solution.

What is the meaning of not protecting the sheet, but showing some obfuscating formulas?

I usually use "protect sheet" and I uncheck the default "Allow all user of this sheet to" Select protected cells". Then there is no way to see anything on the protected sheet, where the know-how is located.

harkunglo gravatar imageharkunglo ( 2019-08-12 14:27:22 +0100 )edit