private static byte[] Decrypt(NppCryptCipherParams cipher, byte[] encryptedData, string password)
{
if (cipher.Encryption.Cipher != "rijndael")
{
throw new Exception($"Cipher algorithm \"{cipher.Encryption.Cipher}\" is not supported now. " +
"Only \"rijndael\" algorithm might be used in the current version");
}
if (cipher.Encryption.Mode != CipherMode.CBC)
{
throw new Exception($"Cipher algorithm mode \"{cipher.Encryption.Mode}\" is not supported now. " +
$"Only \"{nameof(CipherMode.CBC)}\" mode might be used in the current version");
}
if (cipher.Key.Algorithm != "scrypt")
{
throw new Exception($"Key hashing algorithm \"{cipher.Key.Algorithm}\" is not supported now. " +
"Only \"scrypt\" algorithm might be used in the current version");
}
if (!cipher.Key.N.HasValue)
{
throw new Exception($"Parameter '{nameof(cipher.Key.N)}' of key hashing algorithm is not set");
}
if (!cipher.Key.R.HasValue)
{
throw new Exception($"Parameter '{nameof(cipher.Key.R)}' of key hashing algorithm is not set");
}
if (!cipher.Key.P.HasValue)
{
throw new Exception($"Parameter '{nameof(cipher.Key.P)}' of key hashing algorithm is not set");
}
if (cipher.Key.Salt == null)
{
throw new Exception($"Parameter '{nameof(cipher.Key.Salt)}' of key hashing algorithm is not set");
}
var key = ScryptEncoder.CryptoScrypt(Encoding.UTF8.GetBytes(password), cipher.Key.Salt,
cipher.Key.N.Value, cipher.Key.R.Value, cipher.Key.P.Value, cipher.Encryption.KeyLength ?? 32);
using Rijndael rijAlg = Rijndael.Create();
rijAlg.Key = key;
rijAlg.IV = cipher.Iv.Value;
rijAlg.Mode = cipher.Encryption.Mode;
using var ms = new MemoryStream();
using var cs = new CryptoStream(ms, rijAlg.CreateDecryptor(), CryptoStreamMode.Write);
cs.Write(encryptedData, 0, encryptedData.Length);
cs.Close();
var res = ms.ToArray();
ms.Close();
return(res);
}