private static void Decrypt(string sourceFile, string targetFile, IEncryptorFactory factory)
{
using (Stream stream = new FileStream(sourceFile, FileMode.Open))
using (Stream writer = new FileStream(targetFile, FileMode.Create))
using (var encryptStream = new CryptoStream(stream, factory.CreateDecryptor(), CryptoStreamMode.Read))
{
encryptStream.ReadInto(writer);
}
}