Letting users calculate Excel forms on the web while hiding the logic

[Nils Magnus]

(cross-posted to m.p.e.misc and m.p.e.programming to get various
suggestions - sorry about that if offense is taken)

Hello,

We have a number of Excel documents containing formulas and calculations
based on a number of input cells. We want to make these calculations
available on our website, but it's very important that the formulas
remain secret.

I figured that to be sure that malicious users won't be able to get the
formulas involved, they have to be calculated on a server.

As an absolutely last resort, we could recreate the logic in a proper
ASP.NET web site, but this is very tedious and makes updating the
calculations a nightmare. Preferably, one would only have to update the
Excel sheet to make the web calculation similarly updated.

Do anyone have suggestions on how we can accomplish this?

I've taken a look at a couple different "spreadsheet to web converters",
but none of them seem particularly robust and reliable.


Regards,
Nils Magnus

 

[Jim Rech]

Have you considered KDCalc?

http://www.kdcalc.com/

One thing is for sure - if you put a workbook on the web you might as well
stick your formulas on a billboard.

--
Jim
| (cross-posted to m.p.e.misc and m.p.e.programming to get various
| suggestions - sorry about that if offense is taken)
|
| Hello,
|
| We have a number of Excel documents containing formulas and calculations
| based on a number of input cells. We want to make these calculations
| available on our website, but it's very important that the formulas
| remain secret.
|
| I figured that to be sure that malicious users won't be able to get the
| formulas involved, they have to be calculated on a server.
|
| As an absolutely last resort, we could recreate the logic in a proper
| ASP.NET web site, but this is very tedious and makes updating the
| calculations a nightmare. Preferably, one would only have to update the
| Excel sheet to make the web calculation similarly updated.
|
| Do anyone have suggestions on how we can accomplish this?
|
| I've taken a look at a couple different "spreadsheet to web converters",
| but none of them seem particularly robust and reliable.
|
|
| Regards,
| Nils Magnus

 

[Dave Peterson]

Crossposting may not get you any additional responses--most regulars read both
these groups. But it won't hurt, either.

If you keep the formulas in excel, you can lock the cell (and hide the formula)
and then protect the worksheet. But the bad thing is that worksheet protection
is easily broken. Your formulas could be exposed to anyone who really wanted to
see them.

If you move the logic to a macro (VBA), then protect that workbook's project,
this isn't safe either. The project's password can be broken, too.

If you want to create a compiled addin (beyond me), then you may want to read
Chip Pearson's site.
http://www.cpearson.com/excel/CreatingCOMAddIn.aspx

 

[mattiasw]

Two other alternatives are Sharepoint Excel Services (>$7000)

and SpreadsheetConverter to ASP & ASP.NET ($149 per developer). It
generates an ASP.NET page from an Excel spreadsheet with formulas. All
the calculations will work on the ASP.NET-web page.

http://www.spreadsheetconverter.com/excel-asp-net.htm

Detailed info about security at

http://www.spreadsheetconverter.com/faq/faq-secret.htm

Regards,

Mattias at SpreadsheetConverter