C# AES128算法

C#提供了AES加密算法的实现，可以使用System.Security.Cryptography命名空间中的AesManaged类。

以下是一个示例代码：

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

class AES128
{
    static void Main()
    {
        string plainText = "Hello, world!";
        string key = "0123456789abcdef";
        string iv = "1234567890abcdef";

        byte[] encrypted = Encrypt(Encoding.UTF8.GetBytes(plainText), Encoding.UTF8.GetBytes(key), Encoding.UTF8.GetBytes(iv));
        Console.WriteLine("Encrypted: {0}", Convert.ToBase64String(encrypted));

        string decrypted = Decrypt(encrypted, Encoding.UTF8.GetBytes(key), Encoding.UTF8.GetBytes(iv));
        Console.WriteLine("Decrypted: {0}", decrypted);
    }

    public static byte[] Encrypt(byte[] plainTextBytes, byte[] keyBytes, byte[] ivBytes)
    {
        using (AesManaged aes = new AesManaged())
        {
            aes.Mode = CipherMode.CBC;
            aes.Padding = PaddingMode.PKCS7;
            aes.KeySize = 128;
            aes.BlockSize = 128;
            aes.Key = keyBytes;
            aes.IV = ivBytes;

            ICryptoTransform encryptor = aes.CreateEncryptor(aes.Key, aes.IV);
            return encryptor.TransformFinalBlock(plainTextBytes, 0, plainTextBytes.Length);
        }
    }

    public static string Decrypt(byte[] encryptedBytes, byte[] keyBytes, byte[] ivBytes)
    {
        using (AesManaged aes = new AesManaged())
        {
            aes.Mode = CipherMode.CBC;
            aes.Padding = PaddingMode.PKCS7;
            aes.KeySize = 128;
            aes.BlockSize = 128;
            aes.Key = keyBytes;
            aes.IV = ivBytes;

            ICryptoTransform decryptor = aes.CreateDecryptor(aes.Key, aes.IV);
            byte[] decryptedBytes = decryptor.TransformFinalBlock(encryptedBytes, 0, encryptedBytes.Length);

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

在上面的代码中，我们使用了128位的密钥和初始化向量，并使用CBC模式和PKCS7填充。你可以根据需要自定义这些参数。