what kind of key to use for CALG_SHA_256 hash

Question

I am trying to generate a SHA_256 hash across some data. I have started by using the example provided here: example-c-program--creating-an-hmac.

This example uses CALG_HMAC to create the hash, I want to use CALG_SHA_256. I found that I need to change the initial 'provider type' in the CryptAcquireContext() call to PROV_RSA_AES (line 50 in the example) to allow changing the hash algorithm (in line 117) to CALG_SHA_256. But when I do that, I get an NTE_BAD_KEY error.

So, my question is, what kind of key do I need to create an SHA_256 hash. I haven't been able to find any other examples of creating a hash, or actually using the MS crypto functions at all. And none of this is documented that I can find.

Regards,
Greg

Answer 1

Hi

@Greg Wilson-Lindberg

Welcome to Microsoft Q&A!

I suggest you could try replacing the provider's name with "Microsoft Enhanced RSA and AES Cryptographic Provider".

CryptAcquireContext(&hProv, NULL, MS_ENH_RSA_AES_PROV, PROV_RSA_AES, 0);  

For more details I suggest you could refer to the thread: https://stackoverflow.com/questions/4191312/windows-cryptoapi-cryptsignhash-with-calg-sha-256-and-private-key-from-my-keyst

Thank you.

Jeanine

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