NCryptSignHash Error: NTE_INVALID_PARAMETER (0x80090027)
This article explores a common issue encountered when migrating from CryptoAPI to CNG, specifically the "NTE_INVALID_PARAMETER" error returned by the NCryptSignHash function. We will delve into the root cause of this error, examine potential solutions, and provide a practical code example for better understanding.
Understanding the Error
The error code NTE_INVALID_PARAMETER suggests that one or more arguments passed to the NCryptSignHash function are invalid. This issue commonly arises during the migration from CryptoAPI to CNG when handling certificates and keys, as the APIs and underlying mechanisms differ slightly.
Key Considerations
- Certificate Context: The certificate context retrieved from the certificate store must be valid and contain the correct information for the signing operation.
- Key Usage: Verify that the certificate's public key is suitable for signing operations. You can check the key usage extension in the certificate details.
- Key Access Flags: The
NCRYPT_MACHINE_KEY_FLAGflag should be used if the certificate's private key resides in the machine's key store. - Signature Length: The buffer provided to
NCryptSignHashmust be large enough to hold the signature. Ensure you're correctly calculating the signature length based on the chosen cryptographic algorithm. - Hash Algorithm: The hash algorithm used during the signing process should match the algorithm specified in the certificate's
SubjectPublicKeyInfostructure.
Analyzing the Code
The code snippet provided demonstrates a typical scenario involving signing data using a certificate. The key problem lies in the NCryptSignHash function call, where the error arises in the second call.
The issue might stem from an incorrect buffer size for the signature or potential mismatches between the certificate's key usage and the chosen algorithm.
Proposed Solutions
Here are some solutions to address the NTE_INVALID_PARAMETER error in NCryptSignHash:
- Ensure Proper Key Usage: Double-check that the certificate's key usage allows for signing operations. If the key usage extension indicates "Digital Signature" or "Non-Repudiation," it should be suitable for signing.
- Verify Signature Length: Ensure that the signature buffer (
pbSignature) allocated before the secondNCryptSignHashcall is large enough to accommodate the signature. Utilize thedwSigLenvalue returned from the firstNCryptSignHashcall to determine the required size. - Check Hash Algorithm: The hash algorithm employed during signing should align with the one specified in the certificate's
SubjectPublicKeyInfostructure. This can be retrieved using theCertGetCertificateContextPropertyfunction with theCERT_PUBLIC_KEY_INFO_PROP_ID. - Debug and Logging: Implement debugging statements and logging to monitor the values of variables, particularly
dwSigLen, the hash algorithm, and the key usage flags.
Example Code Modification
// ... existing code ...
Check(NCryptSignHash(hKey, NULL, bData, sizeof(bData), NULL, 0, &dwSigLen, 0));
// Allocate the signature buffer based on the returned dwSigLen
pbSignature = (BYTE*)malloc(dwSigLen);
CheckAlloc(pbSignature);
// Check for NULL before proceeding with the second NCryptSignHash call
if (pbSignature == NULL) {
// Handle memory allocation failure
// ...
}
Check(NCryptSignHash(hKey, NULL, bData, sizeof(bData), pbSignature, dwSigLen, &dwSigLen, 0));
// ... remaining code ...
By ensuring that the allocated signature buffer size matches the length retrieved from the first NCryptSignHash call, you can avoid the "NTE_INVALID_PARAMETER" error.
Conclusion
The NTE_INVALID_PARAMETER error when using NCryptSignHash often stems from incorrect argument values. By meticulously checking the key usage, signature buffer size, hash algorithm, and other relevant factors, developers can resolve this issue and successfully integrate CNG into their applications. The code example demonstrates a simple modification to ensure proper signature buffer allocation and prevent the error. Remember to debug thoroughly and review your code for potential inconsistencies during the migration process.
