/// <summary>
/// Method take BCrypt handle as input and returns the CNGKey
/// </summary>
/// <param name="bcryptKeyHandle">Accepts BCrypt Handle</param>
/// <returns>Returns CNG key with NCrypt Handle</returns>
private static CngKey BCryptHandleToNCryptHandle(SafeBCryptKeyHandle bcryptKeyHandle)
{
byte[] keyBlob = BCryptNative.ExportBCryptKey(bcryptKeyHandle, BCryptNative.BCRYPT_ECCPUBLIC_BLOB);
//Now Import the key blob as NCRYPT_KEY_HANDLE
CngKey Key = CngKey.Import(keyBlob, CngKeyBlobFormat.EccPublicBlob);
return Key;
}
private static byte[]? GetProperty(SafeBCryptKeyHandle cryptHandle, string propertyName)
{
Debug.Assert(!cryptHandle.IsInvalid);
unsafe
{
int numBytesNeeded;
NTSTATUS errorCode = Interop.BCrypt.BCryptGetProperty(cryptHandle, propertyName, null, 0, out numBytesNeeded, 0);
if (errorCode != NTSTATUS.STATUS_SUCCESS)
{
return(null);
}
byte[] propertyValue = new byte[numBytesNeeded];
fixed(byte *pPropertyValue = propertyValue)
{
errorCode = Interop.BCrypt.BCryptGetProperty(cryptHandle, propertyName, pPropertyValue, propertyValue.Length, out numBytesNeeded, 0);
}
if (errorCode != NTSTATUS.STATUS_SUCCESS)
{
return(null);
}
Array.Resize(ref propertyValue, numBytesNeeded);
return(propertyValue);
}
}
private static TAlgorithm DecodeECPublicKey <TAlgorithm>(
CertificatePal certificatePal,
Func <CngKey, TAlgorithm> factory,
Action <TAlgorithm, ECParameters> import,
CryptImportPublicKeyInfoFlags importFlags = CryptImportPublicKeyInfoFlags.NONE)
where TAlgorithm : AsymmetricAlgorithm, new()
{
TAlgorithm key;
using (SafeBCryptKeyHandle bCryptKeyHandle = ImportPublicKeyInfo(certificatePal.CertContext, importFlags))
{
CngKeyBlobFormat blobFormat;
byte[] keyBlob;
string? curveName = GetCurveName(bCryptKeyHandle);
if (curveName == null)
{
if (HasExplicitParameters(bCryptKeyHandle))
{
blobFormat = CngKeyBlobFormat.EccFullPublicBlob;
}
else
{
blobFormat = CngKeyBlobFormat.EccPublicBlob;
}
keyBlob = ExportKeyBlob(bCryptKeyHandle, blobFormat);
using (CngKey cngKey = CngKey.Import(keyBlob, blobFormat))
{
key = factory(cngKey);
}
}
else
{
blobFormat = CngKeyBlobFormat.EccPublicBlob;
keyBlob = ExportKeyBlob(bCryptKeyHandle, blobFormat);
ECParameters ecparams = default;
ExportNamedCurveParameters(ref ecparams, keyBlob, false);
ecparams.Curve = ECCurve.CreateFromFriendlyName(curveName);
key = new TAlgorithm();
import(key, ecparams);
}
}
return(key);
}
private static string?GetPropertyAsString(SafeBCryptKeyHandle cryptHandle, string propertyName)
{
Debug.Assert(!cryptHandle.IsInvalid);
byte[]? value = GetProperty(cryptHandle, propertyName);
if (value == null || value.Length == 0)
{
return(null);
}
unsafe
{
fixed(byte *pValue = &value[0])
{
string?valueAsString = Marshal.PtrToStringUni((IntPtr)pValue);
return(valueAsString);
}
}
}
private static byte[] ExportKeyBlob(SafeBCryptKeyHandle bCryptKeyHandle, CngKeyBlobFormat blobFormat)
{
string blobFormatString = blobFormat.Format;
int numBytesNeeded = 0;
NTSTATUS ntStatus = Interop.BCrypt.BCryptExportKey(bCryptKeyHandle, IntPtr.Zero, blobFormatString, null, 0, out numBytesNeeded, 0);
if (ntStatus != NTSTATUS.STATUS_SUCCESS)
{
throw new CryptographicException(Interop.Kernel32.GetMessage((int)ntStatus));
}
byte[] keyBlob = new byte[numBytesNeeded];
ntStatus = Interop.BCrypt.BCryptExportKey(bCryptKeyHandle, IntPtr.Zero, blobFormatString, keyBlob, keyBlob.Length, out numBytesNeeded, 0);
if (ntStatus != NTSTATUS.STATUS_SUCCESS)
{
throw new CryptographicException(Interop.Kernel32.GetMessage((int)ntStatus));
}
Array.Resize(ref keyBlob, numBytesNeeded);
return(keyBlob);
}
private static string?GetCurveName(SafeBCryptKeyHandle bcryptHandle)
{
return(GetPropertyAsString(bcryptHandle, BCRYPT_ECC_CURVE_NAME_PROPERTY));
}
private static bool HasExplicitParameters(SafeBCryptKeyHandle bcryptHandle)
{
byte[]? explicitParams = GetProperty(bcryptHandle, BCRYPT_ECC_PARAMETERS_PROPERTY);
return(explicitParams != null && explicitParams.Length > 0);
}
public static unsafe partial bool CryptImportPublicKeyInfoEx2(CertEncodingType dwCertEncodingType, CERT_PUBLIC_KEY_INFO *pInfo, CryptImportPublicKeyInfoFlags dwFlags, void *pvAuxInfo, out SafeBCryptKeyHandle phKey);
public static unsafe extern bool CryptImportPublicKeyInfoEx2(CertEncodingType dwCertEncodingType, CERT_PUBLIC_KEY_INFO* pInfo, int dwFlags, void* pvAuxInfo, out SafeBCryptKeyHandle phKey);
internal static extern NTSTATUS BCryptExportKey(SafeBCryptKeyHandle hKey, IntPtr hExportKey, string pszBlobType, [Out] byte[] pbOutput, int cbOutput, out int pcbResult, int dwFlags);
