IIS LocalSystem Application pool cannot access my system certificates

Question

I've developed ac# (.NET 4.0) application that signs PDF documents using SecureBlackbox libraries. For my signatures, the signing process uses some installed user certificates from Trusted Root Certification Authorities and Intermediate Certification Authorities . The signing works when I open my testing application as a user, but when i implement this module in a WCF service on IIS (using LocalSystem identity for my Application pool) it doesn't work because it cannot find those certificates.

Note that I've additionally installed those certificates using mmc.exe in Computer account -> Local computer snap-in, but that doesn't solve it. I've also tried to add them to Service account -> Local computer -> World Wide Web Publishing Service (that's IIS, right?), and no success...

Can anyone suggest something else to try? I am not sure at all what IIS is using as account or even if it can access my certificates at all in some other way, please help.

Answer 1

确保证书对本地系统具有读取权限（如果这是您的iis进程被设置为运行的权限）。

Answer 2

What I've found to be correct is that when you use ApplicationPool with identity LocalSystem, the certificates that belong to the system can be managed with mmc.exe when adding snap-in: Computer account -> Local computer. The actual problem was my bad coding while fetching certificates from system store using SBB library. I've solved that and therefore i've solved the problem.