Browser Exam Key does not change

[diegoara96]

Problem: When I send a .seb from one computer to another with 2 different versions of the Safe Exam Browser the key does not change.

Environment:
PC1: last github version of SEB and self-signed code
PC2: virtual machine with altered and unsigned code (the code always return false in IsVirtualMachine()

Steps to reproduce it:

1. Compile and self-sign the code in PC1
2. Use SEB Configuration Tool, configure it, save the .seb and copy the Browser Exam Key,
   copy the .seb to PC2 and click in .seb
3. Now the SEB will send the same Browser Exam Key

Supposedly PC1 and PC2 should send 2 different keys since they have different code. Is this correct?
can be a problem of self-signed ?

Thanks

[dbuechel]

I have not tried it with a self-signed certificate. Could you please debug the relevant code or print some log messages of the individual components of the key calculation? You should find the reason for the behavior you're observing pretty swiftly.

The best place to do so is probably here: https://github.com/SafeExamBrowser/seb-win-refactoring/blob/master/SafeExamBrowser.Browser/Handlers/ResourceHandler.cs#L127

[diegoara96]

2020-05-12 12:31:56.271 [20] - DEBUG: [RequestHandler #1] Browser Exam Key = 0dcee4843d53237456763bfffe9e8a58c1d256bd0fd881dfe5f749ea4a0f035e
2020-05-12 12:31:56.272 [20] - DEBUG: [RequestHandler #1] appConfig.CodeSignatureHash = 
2020-05-12 12:31:56.273 [20] - DEBUG: [RequestHandler #1] appConfig.ProgramBuildVersio = 1.0.0.0
2020-05-12 12:31:56.273 [20] - DEBUG: [RequestHandler #1] settings.ConfigurationKey = 1ba3329f2f7aec7ec289b1b7bd1fda0e87d02e18c2d82b25d953b2b97000435c

appconfig.CodeSignatureHash is empy and im signing the code

[dbuechel]

Ah, yes. That makes perfect sense, given how the signature is retrieved: https://github.com/SafeExamBrowser/seb-win-refactoring/blob/master/SafeExamBrowser.Configuration/ConfigurationData/DataValues.cs#L59

The documentation even states that only Authenticode signatures will return a signer certificate: https://docs.microsoft.com/en-us/dotnet/api/system.reflection.module.getsignercertificate?view=netframework-4.8

[diegoara96]

Okay, that makes sense.It was a problem with my certificate. I'll change it now.Thanks

[dbuechel]

Great!