. Rijndael算法

Rijndael算法是一种高级加密标准（AES）的候选算法，它是由美国国家标准与技术协会（NIST）所选定的。该算法在密码学中被广泛应用于数据加密和解密的过程中。Rijndael算法是一种对称密钥算法，意味着加密和解密使用相同的密钥。它可以用于保护敏感数据的机密性，确保数据在传输和存储过程中不被未经授权的人访问。

Rijndael算法的实现可以使用不同的编程语言，例如C#。下面是一个使用C#实现Rijndael算法的示例：

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

public class RijndaelExample
{
    public static void Main()
    {
        string plainText = "Hello, World!";
        string key = "ThisIsARijndaelKey";
        string iv = "ThisIsARijndaelIV";

        byte[] encryptedBytes = EncryptString(plainText, key, iv);
        string encryptedText = Convert.ToBase64String(encryptedBytes);

        Console.WriteLine("Encrypted Text: " + encryptedText);

        string decryptedText = DecryptString(encryptedBytes, key, iv);

        Console.WriteLine("Decrypted Text: " + decryptedText);
    }

    public static byte[] EncryptString(string plainText, string key, string iv)
    {
        byte[] keyBytes = Encoding.UTF8.GetBytes(key);
        byte[] ivBytes = Encoding.UTF8.GetBytes(iv);

        using (RijndaelManaged rijndael = new RijndaelManaged())
        {
            rijndael.Key = keyBytes;
            rijndael.IV = ivBytes;

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

            using (MemoryStream ms = new MemoryStream())
            {
                using (CryptoStream cs = new CryptoStream(ms, encryptor, CryptoStreamMode.Write))
                {
                    using (StreamWriter sw = new StreamWriter(cs))
                    {
                        sw.Write(plainText);
                    }
                }

                return ms.ToArray();
            }
        }
    }

    public static string DecryptString(byte[] encryptedBytes, string key, string iv)
    {
        byte[] keyBytes = Encoding.UTF8.GetBytes(key);
        byte[] ivBytes = Encoding.UTF8.GetBytes(iv);

        using (RijndaelManaged rijndael = new RijndaelManaged())
        {
            rijndael.Key = keyBytes;
            rijndael.IV = ivBytes;

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

            using (MemoryStream ms = new MemoryStream(encryptedBytes))
            {
                using (CryptoStream cs = new CryptoStream(ms, decryptor, CryptoStreamMode.Read))
                {
                    using (StreamReader sr = new StreamReader(cs))
                    {
                        return sr.ReadToEnd();
                    }
                }
            }
        }
    }
}

这个示例演示了如何使用C#编写的Rijndael算法进行文本加密和解密。在示例中，我们使用了一个密钥和一个初始化向量（IV）来加密和解密文本。加密后的文本以Base64字符串的形式进行存储和传输。