CryptAcquireContextA fails in C++ CLR for "Aloaha Cryptographic Provider"

Question

I have C++ CLR project with both managed and unmanaged code. In this project I loop through list of cryptoproviders and search for suitable.

So I use functions
CryptEnumProvidersA
CryptAcquireContextA

I have C# project which uses C++ project. When I call the method to loop through list of cryptoproviders twice, my application crashes. And it crashes on CryptAcquireContextA. And only on "Aloaha Cryptographic Provider".

When i use debug mode, it also crashes. But when i use debug mode, set breakpoint and pass through code with F10, it works fine.

When i carry out C++ code to separate project, it works fine in all cases.

So, I have two questions here:
1) How such a crash possible? And why it happens?
2) How can I call CryptAcquireContextA to handle such a crash?

My considerations.
1) Some troubles with memory. I was searching for memory leaks, but I didn't find any.
2) I tried to use try-catch, but with no result, CryptAcquireContextA crashes anyway. I would like to use function like "CryptIsValidProvider" or "CryptPingProvider", but I didn't find it.

Evocator

Answer 1

If it works when single-stepping, it's probably a race condition (you're paused in the debugger long enough for some other process or driver to make progress).

Does it matter how much code you single-step through? Does putting a Sleep instead of a breakpoint right before the CryptAcquireContextA call also work?

Proximity

I put 'Sleep' after provider is found, and code works fine. Looks like it's really race condition. Now, is there more elegant decision to handle that? I use 'CryptReleaseContext' after 'CryptAcquireContextA'. But it seems that 'CryptReleaseContext' doesn't free handle or something else immediately, so 'CryptAcquireContextA' fails during next call. – Evocator

You can complain to the developer of that CSP, but even if they pay attention, you'll most likely have to ship with a Sleep call unless you can ensure that all your users will have the latest patched version. Be sure to leave a detailed comment why the Sleep call is there, so someone doesn't end up removing it during maintenance. – Proximity

I discovered that in case of “Aloaha Cryptographic Provider” CryptAcquireContextA returns NULL handle to cryptoprovider. So my decision is to call Sleep if handle is NULL. Thanks. – Evocator