CODEWITHSUNDEEP
cwindowswinapibcrypt
TheAsker
TheAsker

Reputation: 23

Problem with RSA implementation with WinAPI

So I use the CNG framwork from windows in my software(which written exclusively with c). The problem is when I try to implement RSA in my code

The code looks something like this:

    DWORD temp = BCRYPT_SUPPORTED_PAD_OAEP;

    BCryptOpenAlgorithmProvider(PointerToAlgorithmProvider, BCRYPT_RSA_ALGORITHM, NULL, 0);
    
    BCryptGenerateKeyPair(ActualAlgorithmProvider, &handleToKeyObject, 2048, 0);
    
    BCryptSetProperty(ActualAlgorithmProvider, BCRYPT_PADDING_SCHEMES, (PUCHAR)&temp, sizeof(DWORD), 0);

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Unfortunately, BCryptSetProperty return with Invalid handle error.

Upvotes: 0

Views: 726

Answers (2)

Drake Wu
Drake Wu

Reputation: 7170

Confirm from the developer: BCRYPT_PADDING_SCHEMES is used to retrieve the padding schemes supported by the RSA algorithm provider. If you want to use one of the supported padding schemes(OAEP padding scheme for example), you can specify the BCRYPT_PAD_OAEP flag in BCryptEncrypt/BCryptDecrypt.

Upvotes: 0

Soonts
Soonts

Reputation: 21926

One problem is incorrect usage of BCryptSetProperty. The BCRYPT_SUPPORTED_PAD_OAEP symbol is not a variable, it’s a preprocessor macro.

The documentation for BCRYPT_PADDING_SCHEMES says “data type is a DWORD”, this means the size is 4 bytes.

To set that property, declare a local DWORD variable and pass the address to the function:

DWORD val = BCRYPT_SUPPORTED_PAD_OAEP;
BCryptSetProperty( ActualAlgorithmProvider, BCRYPT_PADDING_SCHEMES, (PUCHAR)(&val), 4, 0 );

Upvotes: 1

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