Digitally sign a file.

Hi,

I have a VB6 application that retrieve information from a database table. It create a text file on the disk and upload the file to an FTP site.

All that process works A1.


BUT

I have to digitally sign (encrypt) that file now before uploading it to the FTP site.

Anyone know a free or cheap and secure method to digitally sign a file?
Librairies that I would be able to use in my VB6 application to automate the process.


Someone told me about a free software found on this website www.gpg4win.org but it doesn't seem to provide command line to execute the command without using the user-interface.

--

Thanks for helping !

That link doesn't look like they actuall digitally sign anything. It seems they just encrypt the file. (perhaps even using a proprietary method that requires you distribute their software in order to decrypt??)

If you want to actually digitally sign a file, so that the user that downloads it can view its certificate, and also it gets rid of the "Publisher Could not be verified" message when running downloaded exe files off the web, you need a Code Signing Certificate.

I got mine through InstantSSL because it only costs $99 a year. (Verisign charges something like $500-600)

I suggest you give this site a look through. I got my certificate last week, and I was able to easily integrate code signing into my software, so when my software uploads files via code to our FTP site for customers to download, it also signs the file using our cert. Its all done automatically (I had to code it of course though).

Thanks for the link kleinma. Btw, last I checked verisign was $400 so I assume the pricing has increased. :(

I honestly was putting out a ball park figure Rob, it may still be 400.

Sorry for late response. Didn't notice this thread till now.

I succeeded in using the application of my first post.
I found all the DOS command that I can call from my VB app with a Shell() command. Works great for signing & encrypting files.

did you end up buying a cert from a CA?