Digital Signature support

[itg-assistant]

Tung Ngo asked 2017-12-20 05:58:12 UTC

Hello,

I'm using itextsharp to generate and sign a PDF document in my Desktop Application.

We use a digital certificate from a USB token for signing.

Now I'd like to implement this feature with Wisej. I don't know how to use the USB token at the client side for signing.

Could you give me some advise ?

Regards,

[itg-assistant]

Frank (ITG) answered 2017-12-20 11:33:49 UTC

Hi Tung,

to me it seems that you cannot (or should not) try to access your USB token / certificate from server side code.

You can find a discussion around that topic here:

https://stackoverflow.com/questions/39738912/how-to-sign-pdf-using-usb-token-in-web-application

and a few more pointers here:

https://stackoverflow.com/questions/29210451/itext-generating-pdf-hash-without-certificate-chain

Hope that helps.

Best regards
Frank

[itg-assistant]

Tiago (ITG) answered 2017-12-20 13:10:36 UTC

Hi Tung,

This is a bit like accessing scanners on USB port. Web applications just can't access your USB ports nor can run desktop applications.

The only way I know of solving this problem is to build a glue desktop application: it executes the desktop function you want and uses web services to communicate with server (meaning your Wisej application).

For a sign PDF functionality I would build something like this

• tell Wisej application (WJSRV ) you want to sign a given document

• WJSRV will give the user a token, say ABC123

• user starts the desktop glue application (GLUE)

• GLUE ask the user about the token

• GLUE connects to WJSRV web service and uses the token to get the original document to sign

• GLUE receives the original document

• GLUE takes all the necessary steps to sign the document

• GLUE connects to WJSRV web service and sends the signed document along with the token

• WJSRV receives the signed document and updates the screen so the user can see it's done

Of course you can design something completely different, where the web services are located on the desktop (client) side and are consumed by the application (server) side.

[itg-assistant]

Tung Ngo answered 2017-12-20 14:52:13 UTC

Hi Tiago,

Thank you for your recommendation. I though about a "Glue" Desktop Application, but asking if there is another better approach from professional.

I reckon to have a Desktop Application run and minimize to the window task bar. This application will monitor a download folder.

• When Wisej need to sign a document, it generate the PDF file, assign the document token to the file attributes, then download to the client computer.

• The desktop App see a new PDF file coming in the download folder, it show the user interface for selection the certificate and process the signing.

• The desktop App send back the signed PDF to server using the token in the PDF.

Using your approach require user to launch a glue application manually, which is not desirable in my use case.

I don't know if there is any technology, which allows a wisej application to trigger a desktop application or not.

[itg-assistant]

Tung Ngo answered 2017-12-20 14:58:11 UTC

Another approach is to use the Azure Queue for communication between Wisej and the Desktop application. I think should be better than to monitor a local folder.

[itg-assistant]

Tiago (ITG) answered 2017-12-20 18:12:59 UTC

Hi Tung,

I'm glad to see that you are on the right track. You got the general idea. Now you choose the best solution considering your specific scenario.