Creating an Encryption Key for Data

[Sal Paradise]

I searched the archives to no avail.

Is there any sort of information on how to create an encrypted data set that can be unencrypted by an add-in? While I understand that Excel is in no way secure, I figure that forcing someone to have two files to access the data would be safer than simply trusting data to a passworded excel file/macro.

What I am thinking is as follows:
- Create an encryption algorithm for the numerical cells in a data file
- Encrypt whatever data using the algorithm
- Creating a decryption algorithm with the same algorithm as the encryption as an Add-in
- Whenever the add-in is installed, send an e-mail to me telling me that it's been installed, and relevant information (such as the computer ID and/or IP address if possible)
- On opening the encrypted file with the decryption algorithm add-in installed, it will decrypt the data, do the necessary math (coded in to the add-in), and then delete the raw data so that the leftover data can't be solved backwards to get the raw data

While I understand there would be ways around this, it would prevent a mistaken forwarded e-mail or other slip-up from handing over a chunk of crucial data, and it would give at least some rudimentary idea of how many computers the add-in is installed on.

Is there any step of this that is impossible, and is there some place that this has been done in the past to use as a base?

 

[jongooligan]

Sal

Richard Schollar has a UDF for weak encryption (XOR) in this post:

http://www.mrexcel.com/forum/showthread.php?t=296584

It's much quicker than my code for a Ceasar Cipher from the same post. Not a complete solution to your question but maybe a starting point.

 

[Sal Paradise]

Thank you very much for the link, that certainly is a start.

 

[jongooligan]

pm sent