bool CryptUnprotectData(ref DataBlob pCipherText,
ref string pszDescription,
ref DataBlob pEntropy,
IntPtr pReserved,
ref CryptProtectPromptStruct pPrompt,
int dwFlags,
ref DataBlob pPlainText);
private static unsafe bool TryDecryptStringUsingLocalUser(string encryptedString, out string result)
{
if (string.IsNullOrEmpty(encryptedString))
{
result = string.Empty;
return(false);
}
var optionalEntropy = new DataBlob
{
Size = 0
};
var promptStruct = new CryptProtectPromptStruct
{
Size = 0
};
var byteArray = Convert.FromBase64String(encryptedString);
DataBlob dataIn;
dataIn.Size = byteArray.Length;
var description = string.Empty;
DataBlob dataOut = new DataBlob();
fixed(byte *bytePtr = byteArray)
{
dataIn.Data = (IntPtr)bytePtr;
if (!Win32Crypto.CryptUnprotectData(ref dataIn, ref description, ref optionalEntropy, (IntPtr)null, ref promptStruct,
0, ref dataOut))
{
result = string.Empty;
return(false);
}
var data = (char *)(void *)dataOut.Data;
var charArray = new char[dataOut.Size / 2];
for (var i = 0; i < charArray.Length; ++i)
{
charArray[i] = data[i];
}
result = new string(charArray);
Win32Crypto.LocalFree(dataOut.Data);
return(true);
}
}
