There are some serious limitations to the level of protection you get from Excel. Let's take a look:
Serious limitation 1: It provides only weak intellectual property security (content security), and no location security at all.
Serious limitation 2: While Excel does provide worksheet and workbook password-based protection, cell locking and hiding of formulas, and password protection of macros and Add-ins, the level of protection provided is relatively low, provides a first line of defense only, and can all be broken fairly easily.
Serious limitation 3: Cracking and 'un-protect' programs and services are all over the internet, so with Excel's minimal protection there's very little you can do to stop someone who gets hold of one of your spreadsheets.
Serious limitation 4: Excel does not prevent someone with access to a confidential spreadsheet from copying worksheets, ranges, or formulas and pasting them into another spreadsheet.
Serious limitation 5: The encryption on worksheet and workbook passwords and VBA macro code passwords used by Excel is weak, making it easy and fast to crack them with free software.
In fact, the only native Excel protection system with reasonable integrity is the file encryption offered with recent versions of Excel. But here's the rub: for (authorized) use, the password must be provided - which removes the only strong Excel security measure, and the spreadsheet contents can be accessed and copied as if access had never been restricted.
"Excel protection is good at protecting formulas and text from accidental corruption. Excel protection is not good at hiding sensitive data or formulas. If a determined user has access to a file then he/she can uncover hidden formulas, hidden text and hidden sheets.
The encryption on Worksheet and Workbook structure passwords is extremely weak. Passwords can be cracked in minutes with free software. Even Microsoft acknowledges that worksheet and workbook protection is a 'display' feature and not a 'security' feature. Passwords will only stop the casual user and cannot be relied upon as a security feature in distributed applications." Doug Tyrrell, Excel Consultant
"MS Office file passwords are not secure and were never intended to be. There are a great many third-party utilities available on the Internet to recover lost Office file passwords. Therefore these password features will never be effective for preventing customers from seeing proprietary or trade secret information, for example, or for serious confidentiality or security concerns inside the workplace." Jim Dettwiler
"If I protect my worksheet with a password, is it really secure? No. Don't confuse protection with security. Worksheet protection is not a security feature. Fact is, Excel uses a very simple encryption system for worksheet protection. When you protect a worksheet with a password, that password -- as well as many others -- can be used to unprotect the worksheet. Consequently, it's very easy to "break" a password-protected worksheet. Worksheet protection is not really intended to prevent people from accessing data in a worksheet. If someone really wants to get your data, they can. If you really need to keep your data secure, Excel is not the best platform to use." John Walkenbach
"Excel features related to hiding data or locking data with passwords are not intended to secure or protect confidential information in Excel. These features are merely meant to obscure data or formulas that might confuse some users or to prevent others from viewing or making changes to that data." Microsoft 2006
"It's important to clarify the difference between protection and security. Excel protection isn't a security feature. Protection is meant to prevent well-meaning users from accidentally damaging your work. It won't protect sensitive and confidential data from falling into the wrong hands. For instance, did you know that anyone can copy data from a protected Excel sheet into another workbook or even Google Sheets to access protected data? Excel protection is lost once data is copied somewhere else. It really is that easy, so don't make the mistake of thinking a protected sheet is secure." Online Tech Tips
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If that wasn't enough, remember this: no form of location security is provided by Excel. File access to a particular spreadsheet file can be prevented by:
However, in order for a user to be able to use the spreadsheet, they must have access to the spreadsheet file and any password required to decrypt it. The file contents can then easily be copied as if access had never been restricted.
Spreadsheet Sentry is a software solution that encodes spreadsheets to provide strong content security (authorized users are able to use encoded spreadsheets but are prevented from viewing or editing confidential data or trade secret formulas) and strong location security (encoded spreadsheets will only run on authorized PCs).
You owe it to yourself and your peace of mind to try Spreadsheet Sentry and experience the power. Trial Spreadsheet Sentry by downloading Spreadsheet Sentry Personal now!