SignCheck crashes with StackOverflowException when verifying vsix

[natemcmaster]

Microsoft.DotNet.SignCheck.exe is crashing while trying to verify a vsix file with this error:

System.OverflowException: Arithmetic operation resulted in an overflow.
   at Microsoft.SignCheck.Verification.VsixVerifier.TryGetTimestamp(PackageDigitalSignature packageSignature, Timestamp& timestamp)
   at Microsoft.SignCheck.Verification.VsixVerifier.IsSigned(String path, SignatureVerificationResult result)
   at Microsoft.SignCheck.Verification.VsixVerifier.VerifySignature(String path, String parent)
   at Microsoft.SignCheck.Verification.SignatureVerificationManager.VerifyFiles(IEnumerable`1 files)
   at SignCheck.SignCheck.Run()

I've attached the vsix that it's trying to check:
aspnet_35670.zip

cc @joeloff

[joeloff]

I'll take a look