ASP.NET Stream的加密和解密

在ASP.NET中，使用System.IO.Stream类进行加密和解密操作时，通常需要结合使用System.Security.Cryptography命名空间中的加密算法。以下是一个简单的示例，展示了如何使用AES加密和解密数据。

首先，确保已经安装了System.Security.Cryptography NuGet包。

using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;

namespace ASPNetStreamEncryption
{
    public class StreamEncryptionHelper
    {
        private static readonly byte[] Key = Encoding.UTF8.GetBytes("your-secret-key"); // 16 bytes for AES-128, 24 bytes for AES-192, 32 bytes for AES-256
        private static readonly byte[] IV = Encoding.UTF8.GetBytes("your-initial-vector"); // 16 bytes for AES

        public static Stream EncryptStream(Stream inputStream, Stream outputStream)
        {
            using (Aes aes = Aes.Create())
            {
                aes.Key = Key;
                aes.IV = IV;

                using (ICryptoTransform encryptor = aes.CreateEncryptor(aes.Key, aes.IV))
                {
                    return new CryptoStream(inputStream, encryptor, CryptoStreamMode.Write);
                }
            }
        }

        public static Stream DecryptStream(Stream inputStream, Stream outputStream)
        {
            using (Aes aes = Aes.Create())
            {
                aes.Key = Key;
                aes.IV = IV;

                using (ICryptoTransform decryptor = aes.CreateDecryptor(aes.Key, aes.IV))
                {
                    return new CryptoStream(inputStream, decryptor, CryptoStreamMode.Write);
                }
            }
        }
    }
}

接下来，你可以在ASP.NET应用程序中使用这个StreamEncryptionHelper类来加密和解密数据。例如：

public class EncryptionController : Controller
{
    public IActionResult EncryptFile()
    {
        using (var inputStream = new FileStream("input.txt", FileMode.Open))
        using (var outputStream = new FileStream("output.enc", FileMode.Create))
        {
            Stream encryptedStream = StreamEncryptionHelper.EncryptStream(inputStream, outputStream);
            encryptedStream.Close();
        }

        return Ok("File encrypted successfully.");
    }

    public IActionResult DecryptFile()
    {
        using (var inputStream = new FileStream("output.enc", FileMode.Open))
        using (var outputStream = new FileStream("output.txt", FileMode.Create))
        {
            Stream decryptedStream = StreamEncryptionHelper.DecryptStream(inputStream, outputStream);
            decryptedStream.Close();
        }

        return Ok("File decrypted successfully.");
    }
}

请注意，这个示例仅用于演示目的。在实际应用中，你需要考虑更多的安全因素，例如密钥和初始向量的存储、错误处理和异常管理等。