internal static byte[] GetHashParameter(SafeCapiHashHandle hashHandle, CapiNative.HashParameter parameter)
{
Contract.Requires(hashHandle != null);
Contract.Requires(CapiNative.HashParameter.AlgorithmId <= parameter && parameter <= CapiNative.HashParameter.HashSize);
Contract.Ensures(Contract.Result <byte[]>() != null);
//
// Determine the maximum size of the parameter and retrieve it
//
int parameterSize = 0;
if (!CapiNative.UnsafeNativeMethods.CryptGetHashParam(hashHandle, parameter, null, ref parameterSize, 0))
{
throw new CryptographicException(Marshal.GetLastWin32Error());
}
Debug.Assert(0 < parameterSize, "Invalid parameter size returned");
byte[] parameterValue = new byte[parameterSize];
if (!CapiNative.UnsafeNativeMethods.CryptGetHashParam(hashHandle, parameter, parameterValue, ref parameterSize, 0))
{
throw new CryptographicException(Marshal.GetLastWin32Error());
}
// CAPI may have asked for a larger buffer than it used, so only copy the used bytes
if (parameterSize != parameterValue.Length)
{
byte[] realValue = new byte[parameterSize];
Buffer.BlockCopy(parameterValue, 0, realValue, 0, parameterSize);
parameterValue = realValue;
}
return(parameterValue);
}
public static extern bool CryptGetHashParam(SafeCapiHashHandle hHash, CapiNative.HashParameter dwParam, [Out, MarshalAs(UnmanagedType.LPArray)] byte[] pbData, [In, Out] ref int pdwDataLen, int dwFlags);
