I am exploring the use of Windows CNG to replace some OpenSSL-based code that takes advantage of AES in counter mode. From the outside, everything should look the same after the switch.
BCRYPT_CHAINING_MODE in this piece of CNG documentation gives me the impression that the only counter modes supported are
BCRYPT_CHAIN_MODE_CCM, which sets the algorithm's chaining mode to counter with CBC-MAC mode (CCM) and
BCRYPT_CHAIN_MODE_GCM, which sets the algorithm's chaining mode to Galois/counter mode (GCM)
I have no experience with CCM or GCM and would like to understand whether it is possible to use them in such a way that it can interoperate with CTR, by "disabling" the authentication part or in any other way. I did not find any indication that that is possible indeed, but on the other hand, I would be surprised if CNG does not support AES-CTR.
Maybe my question should have been "does Windows CNG support AES-CTR" to get a more direct answer :-)
Update: On another Microsoft webpage, in the section Cryptographic Algorithms, the table called "Table 12 – Advanced Encryption Standard (AES)" mentions "CTR( int only; 128 , 192 , 256 )", which I suppose means that it is internal functionality only.
I think this question is related: What is wrong with AES-CTR-HMAC-SHA256 - or why is it not in TLS?