.Net中对称加密的实现

常见对称加密算法及优缺点

DES（Data Encryption Standard）

优点：是最早被广泛应用的加密算法，算法公开，实现简单，效率较高。
缺点：密钥长度较短（56 位），在现代计算能力下，安全性较低，容易被暴力破解。

3DES（Triple DES）

优点：在 DES 的基础上进行了改进，通过多次使用 DES 算法，增加了密钥长度，提高了安全性。
缺点：由于多次使用 DES 算法，加密和解密速度相对较慢。

AES（Advanced Encryption Standard）

优点：是目前应用最广泛的对称加密算法，密钥长度可选（128 位、192 位、256 位），安全性高，加密和解密速度快。
缺点：相对来说，算法复杂度较高，实现难度较大。

示例代码

cs 复制代码

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

class SymmetricEncryption
{
    // DES 加密
    public static string DESEncrypt(string plainText, string key)
    {
        using (DESCryptoServiceProvider des = new DESCryptoServiceProvider())
        {
            byte[] inputBytes = Encoding.UTF8.GetBytes(plainText);
            byte[] keyBytes = Encoding.UTF8.GetBytes(key);
            byte[] encryptedBytes;

            using (MemoryStream ms = new MemoryStream())
            {
                using (CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(keyBytes, keyBytes), CryptoStreamMode.Write))
                {
                    cs.Write(inputBytes, 0, inputBytes.Length);
                    cs.FlushFinalBlock();
                    encryptedBytes = ms.ToArray();
                }
            }

            return Convert.ToBase64String(encryptedBytes);
        }
    }

    // DES 解密
    public static string DESDecrypt(string cipherText, string key)
    {
        using (DESCryptoServiceProvider des = new DESCryptoServiceProvider())
        {
            byte[] inputBytes = Convert.FromBase64String(cipherText);
            byte[] keyBytes = Encoding.UTF8.GetBytes(key);
            byte[] decryptedBytes;

            using (MemoryStream ms = new MemoryStream())
            {
                using (CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(keyBytes, keyBytes), CryptoStreamMode.Write))
                {
                    cs.Write(inputBytes, 0, inputBytes.Length);
                    cs.FlushFinalBlock();
                    decryptedBytes = ms.ToArray();
                }
            }

            return Encoding.UTF8.GetString(decryptedBytes);
        }
    }

    // 3DES 加密
    public static string TripleDESEncrypt(string plainText, string key)
    {
        using (TripleDESCryptoServiceProvider tripleDes = new TripleDESCryptoServiceProvider())
        {
            byte[] inputBytes = Encoding.UTF8.GetBytes(plainText);
            byte[] keyBytes = Encoding.UTF8.GetBytes(key);
            byte[] encryptedBytes;

            using (MemoryStream ms = new MemoryStream())
            {
                using (CryptoStream cs = new CryptoStream(ms, tripleDes.CreateEncryptor(keyBytes, keyBytes), CryptoStreamMode.Write))
                {
                    cs.Write(inputBytes, 0, inputBytes.Length);
                    cs.FlushFinalBlock();
                    encryptedBytes = ms.ToArray();
                }
            }

            return Convert.ToBase64String(encryptedBytes);
        }
    }

    // 3DES 解密
    public static string TripleDESDecrypt(string cipherText, string key)
    {
        using (TripleDESCryptoServiceProvider tripleDes = new TripleDESCryptoServiceProvider())
        {
            byte[] inputBytes = Convert.FromBase64String(cipherText);
            byte[] keyBytes = Encoding.UTF8.GetBytes(key);
            byte[] decryptedBytes;

            using (MemoryStream ms = new MemoryStream())
            {
                using (CryptoStream cs = new CryptoStream(ms, tripleDes.CreateDecryptor(keyBytes, keyBytes), CryptoStreamMode.Write))
                {
                    cs.Write(inputBytes, 0, inputBytes.Length);
                    cs.FlushFinalBlock();
                    decryptedBytes = ms.ToArray();
                }
            }

            return Encoding.UTF8.GetString(decryptedBytes);
        }
    }

    // AES 加密
    public static string AESEncrypt(string plainText, string key)
    {
        using (Aes aesAlg = Aes.Create())
        {
            byte[] inputBytes = Encoding.UTF8.GetBytes(plainText);
            byte[] keyBytes = Encoding.UTF8.GetBytes(key);
            aesAlg.Key = keyBytes;
            aesAlg.GenerateIV();

            byte[] encryptedBytes;

            using (MemoryStream ms = new MemoryStream())
            {
                using (CryptoStream cs = new CryptoStream(ms, aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV), CryptoStreamMode.Write))
                {
                    cs.Write(inputBytes, 0, inputBytes.Length);
                    cs.FlushFinalBlock();
                    encryptedBytes = ms.ToArray();
                }

                byte[] combinedBytes = new byte[aesAlg.IV.Length + encryptedBytes.Length];
                Array.Copy(aesAlg.IV, 0, combinedBytes, 0, aesAlg.IV.Length);
                Array.Copy(encryptedBytes, 0, combinedBytes, aesAlg.IV.Length, encryptedBytes.Length);

                return Convert.ToBase64String(combinedBytes);
            }
        }
    }

    // AES 解密
    public static string AESDecrypt(string cipherText, string key)
    {
        byte[] combinedBytes = Convert.FromBase64String(cipherText);
        byte[] iv = new byte[16];
        byte[] encryptedBytes = new byte[combinedBytes.Length - iv.Length];

        Array.Copy(combinedBytes, 0, iv, 0, iv.Length);
        Array.Copy(combinedBytes, iv.Length, encryptedBytes, 0, encryptedBytes.Length);

        using (Aes aesAlg = Aes.Create())
        {
            byte[] keyBytes = Encoding.UTF8.GetBytes(key);
            aesAlg.Key = keyBytes;
            aesAlg.IV = iv;

            byte[] decryptedBytes;

            using (MemoryStream ms = new MemoryStream())
            {
                using (CryptoStream cs = new CryptoStream(ms, aesAlg.CreateDecryptor(aesAlg.Key, aesAlg.IV), CryptoStreamMode.Write))
                {
                    cs.Write(encryptedBytes, 0, encryptedBytes.Length);
                    cs.FlushFinalBlock();
                    decryptedBytes = ms.ToArray();
                }
            }

            return Encoding.UTF8.GetString(decryptedBytes);
        }
    }

    static void Main()
    {
        string plainText = "Hello, World!";
        string desKey = "abcdefgh"; // DES 密钥长度必须为 8 字节
        string tripleDesKey = "abcdefghijklmnopqrstuvwx"; // 3DES 密钥长度必须为 24 字节
        string aesKey = "abcdefghijklmnop"; // AES 密钥长度可以为 16、24 或 32 字节

        // DES 加密和解密
        string desCipherText = DESEncrypt(plainText, desKey);
        string desDecryptedText = DESDecrypt(desCipherText, desKey);
        Console.WriteLine($"DES 加密结果: {desCipherText}");
        Console.WriteLine($"DES 解密结果: {desDecryptedText}");

        // 3DES 加密和解密
        string tripleDesCipherText = TripleDESEncrypt(plainText, tripleDesKey);
        string tripleDesDecryptedText = TripleDESDecrypt(tripleDesCipherText, tripleDesKey);
        Console.WriteLine($"3DES 加密结果: {tripleDesCipherText}");
        Console.WriteLine($"3DES 解密结果: {tripleDesDecryptedText}");

        // AES 加密和解密
        string aesCipherText = AESEncrypt(plainText, aesKey);
        string aesDecryptedText = AESDecrypt(aesCipherText, aesKey);
        Console.WriteLine($"AES 加密结果: {aesCipherText}");
        Console.WriteLine($"AES 解密结果: {aesDecryptedText}");
    }
}