c#中怎么实现sm4加密

在C#中实现SM4加密可以通过使用第三方库来实现。一个常用的库是Bouncy Castle，可以通过NuGet安装。

首先，安装Bouncy Castle库：

Install-Package BouncyCastle 

然后，使用以下代码示例实现SM4加密：

using System; using System.IO; using System.Text; using System.Security.Cryptography; using Org.BouncyCastle.Crypto; using Org.BouncyCastle.Crypto.Parameters; using Org.BouncyCastle.Crypto.Engines;  public class SM4Encryption {     public static string Encrypt(string plaintext, string key)     {         byte[] keyBytes = Encoding.UTF8.GetBytes(key);         byte[] plaintextBytes = Encoding.UTF8.GetBytes(plaintext);          SM4Engine sm4 = new SM4Engine();         KeyParameter keyParam = new KeyParameter(keyBytes);         sm4.Init(true, keyParam);          byte[] ciphertextBytes = new byte[plaintextBytes.Length];         for (int i = 0; i < plaintextBytes.Length; i++)         {             sm4.ProcessBlock(plaintextBytes, i, ciphertextBytes, i);         }          return Convert.ToBase64String(ciphertextBytes);     }      public static string Decrypt(string ciphertext, string key)     {         byte[] keyBytes = Encoding.UTF8.GetBytes(key);         byte[] ciphertextBytes = Convert.FromBase64String(ciphertext);          SM4Engine sm4 = new SM4Engine();         KeyParameter keyParam = new KeyParameter(keyBytes);         sm4.Init(false, keyParam);          byte[] plaintextBytes = new byte[ciphertextBytes.Length];         for (int i = 0; i < ciphertextBytes.Length; i++)         {             sm4.ProcessBlock(ciphertextBytes, i, plaintextBytes, i);         }          return Encoding.UTF8.GetString(plaintextBytes);     } } 

使用示例：

string plaintext = "Hello, SM4!"; string key = "0123456789abcdeffedcba9876543210"; string ciphertext = SM4Encryption.Encrypt(plaintext, key); Console.WriteLine("Ciphertext: " + ciphertext);  string decryptedText = SM4Encryption.Decrypt(ciphertext, key); Console.WriteLine("Decrypted Text: " + decryptedText); 

请注意，以上代码示例仅供参考，并不保证在所有情况下都能正确工作。在实际应用中，建议根据具体需求进行适当调整和优化。