Question

我正在尝试用C＃加密通用流。虽然程序没有问题，但加密和解密在转换为字符串时返回空白。任何帮助表示赞赏。

    public byte[] AES_Encrypt(byte[] bytesToBeEncrypted, byte[] passwordBytes)
        {
            byte[] encryptedBytes = null;

            // Set your salt here, change it to meet your flavor:
            // The salt bytes must be at least 8 bytes.
            byte[] saltBytes = new byte[] { 1, 2, 3, 4, 5, 6, 7, 8 };

            using (MemoryStream ms = new MemoryStream())
            {
                using (RijndaelManaged AES = new RijndaelManaged())
                {
                    AES.KeySize = 256;
                    AES.BlockSize = 128;

                    var key = new Rfc2898DeriveBytes(passwordBytes, saltBytes, 10000);
                    AES.Key = key.GetBytes(AES.KeySize / 8);
                    AES.IV = key.GetBytes(AES.BlockSize / 8);

                    AES.Mode = CipherMode.CBC;

                    using (var cs = new CryptoStream(ms, AES.CreateEncryptor(), CryptoStreamMode.Write))
                    {
                        cs.Write(bytesToBeEncrypted, 0, bytesToBeEncrypted.Length);
                        cs.Close();
                    }
                    encryptedBytes = ms.ToArray();
                }
            }

            return encryptedBytes;
        }

        public byte[] AES_Decrypt(byte[] bytesToBeDecrypted, byte[] passwordBytes)
        {
            byte[] decryptedBytes = null;

            // Set your salt here, change it to meet your flavor:
            // The salt bytes must be at least 8 bytes.
            byte[] saltBytes = new byte[] { 1, 2, 3, 4, 5, 6, 7, 8 };

            using (MemoryStream ms = new MemoryStream())
            {
                using (RijndaelManaged AES = new RijndaelManaged())
                {
                    AES.KeySize = 256;
                    AES.BlockSize = 128;

                    var key = new Rfc2898DeriveBytes(passwordBytes, saltBytes, 10000);
                    AES.Key = key.GetBytes(AES.KeySize / 8);
                    AES.IV = key.GetBytes(AES.BlockSize / 8);

                    AES.Mode = CipherMode.CBC;

                    using (var cs = new CryptoStream(ms, AES.CreateDecryptor(), CryptoStreamMode.Write))
                    {
                        cs.Write(bytesToBeDecrypted, 0, bytesToBeDecrypted.Length);
                        cs.Close();
                    }
                    decryptedBytes = ms.ToArray();
                }
            }

            return decryptedBytes;
        }

        private void Encrypt(Stream input, Stream output, String password)
        {
            input.Position = 0;
            byte[] passwordBytes = Encoding.UTF8.GetBytes(password);
            using (var stream = new MemoryStream())
            {
                byte[] buffer = new byte[2048]; // read in chunks of 2KB
                int bytesRead;
                while ((bytesRead = input.Read(buffer, 0, buffer.Length)) > 0)
                {
                    stream.Write(buffer, 0, bytesRead);
                    var tmp = AES_Encrypt(buffer, passwordBytes);
                    output.Write(tmp, 0, tmp.Length);
                }
            }

        }

        private void Decrypt(Stream input, Stream output, String password)
        {
            input.Position = 0;
            byte[] passwordBytes = Encoding.UTF8.GetBytes(password);
            using (var stream = new MemoryStream())
            {
                byte[] buffer = new byte[2048]; // read in chunks of 2KB
                int bytesRead;
                while ((bytesRead = input.Read(buffer, 0, buffer.Length)) > 0)
                {
                    stream.Write(buffer, 0, bytesRead);
                    var tmp = AES_Decrypt(buffer, passwordBytes);
                    output.Write(tmp, 0, tmp.Length);
                }
            }

        }

        static void Main(string[] args)
        {

            Program obj = new Program();
            var message = new MemoryStream();
            var cipher = new MemoryStream();
            string tmp = "This is a test if the encryption is working!";

            StreamWriter sw = new StreamWriter(message);
            sw.Write(tmp);

            obj.Encrypt(message, cipher, "password");

            cipher.Position = 0;
            message = new MemoryStream();

            obj.Decrypt(cipher, message, "password");

            using (var memoryStream = new MemoryStream())
            {
                message.CopyTo(memoryStream);
                var bytesdecrypt = memoryStream.ToArray();
                string result = Encoding.UTF8.GetString(bytesdecrypt);
                Console.WriteLine(result);
                Console.ReadLine();
            }


        }
    }
}

这个问题可能发生在我从溪流中读书和写作时。

Answer 1

此代码存在许多问题。

没有解密的原因是因为您忘记在执行message之前重置message.CopyTo(memoryStream)流，因为CopyTo在当前位置工作但您没有更改解密后的位置。

您可以使用
重置它
```
message.Position = 0;
```
如果对任意数据进行加密，则使用某些操作模式（如CBC）的AES是不够的。我们通常需要某种填充方案。在C＃中，默认方案是PKCS＃7填充。即使明文已经是块大小的倍数，也总是添加明确的填充。在这些情况下，会添加一个完整的填充块。

现在的问题是你在加密和解密期间读取了2048个字节的块，但加密产生了2064个字节的密文块，在解密过程中必须这样读取。这是一个简单的修复，但最好一直使用流，而不是加密这些单独的块。
您为每个2048字节的块调用Rfc2898DeriveBytes，但它永远不会更改。引入随机性，但实际使用随机盐和随机IV，或缓存密钥。（随机盐和随机IV仍然是达到语义安全所必需的）

使用RijndaelManaged在C＃中加密/解密流

1 个答案: