public bool DecryptString(uint version, byte[] pbSaltBlob, ref byte[] EncryptBuffer, ref uint dwInLen)
{
IntPtr enryptionKey;
if (!keyMap.TryGetValue(version, out enryptionKey))
{
return(false);
}
IntPtr hAESKey = IntPtr.Zero;
if (!CryptoWinApi.CryptDuplicateKey(enryptionKey, IntPtr.Zero, 0, ref hAESKey))
{
CryptoWinApi.Failed("CryptDuplicateKey");
return(false);
}
// assign salt to the key
if (!CryptoWinApi.CryptSetKeyParam(hAESKey, CryptoWinApi.KP_IV, pbSaltBlob, 0))
{
CryptoWinApi.Failed("CryptSetKeyParam");
return(false);
}
if (!CryptoWinApi.CryptDecrypt(hAESKey, IntPtr.Zero, true, 0, EncryptBuffer, ref dwInLen))
{
CryptoWinApi.Failed("CryptDecrypt");
return(false);
}
return(true);
}
public static void Failed(string command)
{
uint lastError = CryptoWinApi.GetLastError();
StringBuilder sb = new StringBuilder(500);
try
{
// get message for last error
FormatMessage(CryptoWinApi.FORMAT_MESSAGE_FROM_SYSTEM,
null, lastError, 0, sb, 500, null);
}
catch
{
// error calling FormatMessage
sb.Append("N/A.");
}
}
private bool GetKey(string keyFile)
{
//try
//{
using (var fs = new FileStream(keyFile, FileMode.Open, FileAccess.Read))
{
using (var br = new BinaryReader(fs))
{
br.ReadUInt32(); // recordSize
var keyVersion = br.ReadUInt32();
br.ReadUInt32(); // IVBlobLength
br.ReadUInt32(); // ElapsedTime
var keyBlobLength = br.ReadUInt32();
br.ReadUInt32(); // hashKeyBlobLength
var encryptionKeyBlob = br.ReadBytes((int)keyBlobLength);
IntPtr hCryptProv = IntPtr.Zero;
if (!CryptoWinApi.CryptAcquireContext(ref hCryptProv, null, null, CryptoWinApi.PROV_RSA_AES, CryptoWinApi.CRYPT_VERIFYCONTEXT | CryptoWinApi.CRYPT_MACHINE_KEYSET | CryptoWinApi.CRYPT_SILENT))
{
return(false);
}
var enryptionKey = IntPtr.Zero;
if (!CryptoWinApi.CryptImportKey(hCryptProv, encryptionKeyBlob, keyBlobLength, IntPtr.Zero, 0, ref enryptionKey))
{
return(false);
}
keyMap.Add(keyVersion, enryptionKey);
return(true);
}
}
//}
//catch (Exception)
//{
// return false;
//}
}
