Check self signature status

StewartBW 285

Hello

Using VB.net or C# .net framework 4.0, is it possible to add a self check for the digital signature of assembly file?

So assembly file should check itself to make sure if it's signed using my code signing certificate and if not, or file is modified and the certificate is invalid, terminate the app.

Thanks for the help.

1 answer

Jiachen Li-MSFT 26,591 Reputation points Microsoft Vendor

2024-04-16T05:57:25.2833333+00:00

Hi @StewartBW ,

You can use AssemblyName.GetPublicKey Method to retrieve the public key from the assembly. Then compare the retrieved public key with the public key of your code signing certificate.

Best Regards.

Jiachen Li

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StewartBW 285 Reputation points

2024-04-16T06:55:57.4433333+00:00

Thanks, I'm always getting the error and code is terminated

Are you sure this will obtain the public key of certificate used to sign the assembly?

assembly.GetName().GetPublicKey()

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Jiachen Li-MSFT 26,591 Reputation points Microsoft Vendor

2024-04-18T06:30:35.4966667+00:00

Hi @StewartBW ，

AssemblyName.GetPublicKey can only get the public key of the assembly itself.

It should be pointed out that the digital signature itself provides the necessary protection against tampering, so manual verification in your code isn’t required. If the signature is valid, you can trust the DLL. If you suspect tampering, the operating system will reject the DLL during loading.
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