Windows C/C++ Crypto API Examples and tips

Question

I'm asking this question because I've spent the best part of a day trawling through msdn docs and other opaque sources for simple straightforward guidelines on how to get started with the Windows C/C++ Crypto API.

What I'd like to see is some example code, typical include paths, linking guidelines, etc, anything useful really. I know this is an imprecise question but I reckon imprecise answers are better none at all.

I'll get the ball rolling with my own meager findings...

Leukorrhea

Do you mean classic CryptoAPI as in Win2k and XP, or CNG ("CryptoAPI Next Generation") as in Vista and Win7? The two are not the same. – Hemicellulose

Hmm, I suppose I mean the CryptoAPI but I'm compiling on a Windows 7 system. – Leukorrhea

It would be better to use CNG – Jared

Answer 1

Here's a bunch of examples I've found....

• Example C Program: Listing the Certificates in a Store
• Example C Program: Using CryptAcquireContext
• Example C Program: Enumerating CSP Providers and Provider Types
• Example C Code for Opening Certificate Stores
• Example C Program: Sending and Receiving a Signed and Encrypted Message
• Example C Program: Signing a Hash and Verifying the Hash Signature

MSDN has these examples scattered around the docs

This website provides a good overview of the concepts along with cross-platform examples

Leukorrhea

You can just merge your two answers. – Freeway

Wow, and not an example that simply encrypts data. – Scorch

Answer 2

The msdn docs are here: http://msdn.microsoft.com/en-us/library/aa380252.aspx

This is the main include file: #include <wincrypt.h>

The cryptography bits are included as part of the Windows SDK, which is typically installed in %PROGRAMFILES(x86)%\Microsoft SDKs\Windows\SDKVERSION (e.g., C:\Program Files\Microsoft SDKs\Windows\v6.0A). The headers are typically in %WINDOWSSDK%\Include, and the related libraries are in %WINDOWSSDK%\Lib.

You must link to the cryptography libraries explicitly. Assuming you're in Visual Studio, you can add the reference by right clicking on the C++ project, choosing properties, and selecting Configuration Properties -> Linker on the treeview at left. You can then specify crypt32.lib in the input field on the right.

Alternately, (assuming you're using msvc++) add

#pragma comment(lib, "crypt32.lib")

to your source.

Leukorrhea

I significantly revised and expanded this answer. Please check to ensure you think the changes are useful :) – Anaemic

Ah!, thanks, I would never have thought of using the #pragma directive. – Leukorrhea

I was using #include <wincrypt.h> and #include <cryptdlg.h> in my VC++2017 project and I got error "LNK2019" when callling their api functions. Addding the line #pragma comment(lib, "crypt32.lib") solved it! Thanks :D – Brooklet

Wow, thanks, I wonder why this is not part of any MSDN guide. – Elmore

Answer 3

There is also a lengthy example "Encryption using the Win32 Crypto API" over at the Code Project.

Unmeaning

Answer 4

After searching for several hours, I found this one here: https://learn.microsoft.com/en-us/troubleshoot/windows/win32/get-information-authenticode-signed-executables

It's detailed, and it works.

Booher