C#的CryptographicException是什么？加密异常处理

CryptographicException

CryptographicException

try-catch

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

public class CryptoHandler
{
    public string Decrypt(byte[] encryptedData, byte[] key, byte[] iv)
    {
        using (Aes aesAlg = Aes.Create())
        {
            aesAlg.Key = key;
            aesAlg.IV = iv;
            aesAlg.Padding = PaddingMode.PKCS7; // 确保与加密时一致
            aesAlg.Mode = CipherMode.CBC;       // 确保与加密时一致

            ICryptoTransform decryptor = aesAlg.CreateDecryptor(aesAlg.Key, aesAlg.IV);

            try
            {
                using (MemoryStream msDecrypt = new MemoryStream(encryptedData))
                {
                    using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
                    {
                        using (StreamReader srDecrypt = new StreamReader(csDecrypt))
                        {
                            return srDecrypt.ReadToEnd();
                        }
                    }
                }
            }
            catch (CryptographicException ex)
            {
                // 这里是处理异常的关键点
                // 1. 记录详细的异常信息，包括InnerException
                Console.WriteLine($"加密操作失败：{ex.Message}");
                if (ex.InnerException != null)
                {
                    Console.WriteLine($"内部异常：{ex.InnerException.Message}");
                }
                // 2. 根据具体场景决定如何响应
                //    - 如果是用户输入错误，可以给用户友好的提示
                //    - 如果是系统配置问题，可能需要管理员介入
                //    - 绝不能把原始异常信息直接暴露给最终用户
                throw new ApplicationException("解密失败，请检查数据或配置。", ex); // 重新抛出更通用的异常
            }
            catch (Exception ex) // 捕获其他可能的异常
            {
                Console.WriteLine($"发生未知错误：{ex.Message}");
                throw;
            }
        }
    }

    // 假设有对应的加密方法
    public byte[] Encrypt(string plainText, byte[] key, byte[] iv)
    {
        using (Aes aesAlg = Aes.Create())
        {
            aesAlg.Key = key;
            aesAlg.IV = iv;
            aesAlg.Padding = PaddingMode.PKCS7;
            aesAlg.Mode = CipherMode.CBC;

            ICryptoTransform encryptor = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV);

            using (MemoryStream msEncrypt = new MemoryStream())
            {
                using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
                {
                    using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
                    {
                        swEncrypt.Write(plainText);
                    }
                    return msEncrypt.ToArray();
                }
            }
        }
    }

    // 示例用法
    public static void Main(string[] args)
    {
        CryptoHandler handler = new CryptoHandler();
        byte[] key = new byte[32]; // 256-bit key
        byte[] iv = new byte[16];  // 128-bit IV
        RandomNumberGenerator.Fill(key);
        RandomNumberGenerator.Fill(iv);

        string originalText = "Hello, world! This is a secret message.";

        // 正常加密解密
        byte[] encrypted = handler.Encrypt(originalText, key, iv);
        string decrypted = handler.Decrypt(encrypted, key, iv);
        Console.WriteLine($"原始: {originalText}");
        Console.WriteLine($"解密后: {decrypted}");

        Console.WriteLine("\n--- 模拟错误情况 ---");

        // 模拟密钥错误
        byte[] wrongKey = new byte[32];
        RandomNumberGenerator.Fill(wrongKey);
        try
        {
            Console.WriteLine("尝试使用错误的密钥解密...");
            handler.Decrypt(encrypted, wrongKey, iv);
        }
        catch (ApplicationException appEx)
        {
            Console.WriteLine($"捕获到应用层异常: {appEx.Message}");
        }

        // 模拟数据篡改
        byte[] tamperedEncrypted = (byte[])encrypted.Clone();
        if (tamperedEncrypted.Length > 5)
        {
            tamperedEncrypted[5] = (byte)(tamperedEncrypted[5] ^ 0xFF); // 篡改一个字节
        }
        try
        {
            Console.WriteLine("尝试解密被篡改的数据...");
            handler.Decrypt(tamperedEncrypted, key, iv);
        }
        catch (ApplicationException appEx)
        {
            Console.WriteLine($"捕获到应用层异常: {appEx.Message}");
        }
    }
}

CryptographicException

CryptographicException