c# sm4加密解密

以下是C#中使用SM4算法进行加密和解密的示例代码：

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

class Program
{
    static void Main(string[] args)
    {
        string plainText = "Hello, world!"; // 待加密的明文
        string key = "0123456789abcdef"; // 密钥，必须为16个字符

        byte[] encrypted = SM4Encrypt(Encoding.UTF8.GetBytes(plainText), Encoding.UTF8.GetBytes(key));
        Console.WriteLine("Encrypted: " + BitConverter.ToString(encrypted).Replace("-", ""));

        byte[] decrypted = SM4Decrypt(encrypted, Encoding.UTF8.GetBytes(key));
        Console.WriteLine("Decrypted: " + Encoding.UTF8.GetString(decrypted));
    }

    static byte[] SM4Encrypt(byte[] plainText, byte[] key)
    {
        using (SM4 sm4 = new SM4())
        {
            sm4.Key = key;
            sm4.Mode = CipherMode.ECB;
            sm4.Padding = PaddingMode.Zeros;

            using (ICryptoTransform encryptor = sm4.CreateEncryptor())
            {
                return encryptor.TransformFinalBlock(plainText, 0, plainText.Length);
            }
        }
    }

    static byte[] SM4Decrypt(byte[] cipherText, byte[] key)
    {
        using (SM4 sm4 = new SM4())
        {
            sm4.Key = key;
            sm4.Mode = CipherMode.ECB;
            sm4.Padding = PaddingMode.Zeros;

            using (ICryptoTransform decryptor = sm4.CreateDecryptor())
            {
                return decryptor.TransformFinalBlock(cipherText, 0, cipherText.Length);
            }
        }
    }
}

需要注意的是，SM4算法的密钥长度必须为16个字符，如果不足16个字符则需要进行补齐。此外，SM4算法的工作模式和填充模式也需要指定，上述示例中使用的是ECB模式和零填充模式。