请写一个C#的加密函数

以下是一个简单的基于AES算法的加密函数示例：

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

public static class EncryptionHelper
{
    private static readonly byte[] Salt = new byte[] { 1, 2, 3, 4, 5, 6, 7, 8 };

    public static string Encrypt(string plainText, string password)
    {
        byte[] plainBytes = Encoding.UTF8.GetBytes(plainText);

        using (Aes aes = Aes.Create())
        {
            Rfc2898DeriveBytes keyDerivation = new Rfc2898DeriveBytes(password, Salt);
            aes.Key = keyDerivation.GetBytes(aes.KeySize / 8);
            aes.IV = keyDerivation.GetBytes(aes.BlockSize / 8);

            using (MemoryStream memoryStream = new MemoryStream())
            {
                using (CryptoStream cryptoStream = new CryptoStream(memoryStream, aes.CreateEncryptor(), CryptoStreamMode.Write))
                {
                    cryptoStream.Write(plainBytes, 0, plainBytes.Length);
                    cryptoStream.FlushFinalBlock();
                }

                byte[] encryptedBytes = memoryStream.ToArray();
                return Convert.ToBase64String(encryptedBytes);
            }
        }
    }

    public static string Decrypt(string encryptedText, string password)
    {
        byte[] encryptedBytes = Convert.FromBase64String(encryptedText);

        using (Aes aes = Aes.Create())
        {
            Rfc2898DeriveBytes keyDerivation = new Rfc2898DeriveBytes(password, Salt);
            aes.Key = keyDerivation.GetBytes(aes.KeySize / 8);
            aes.IV = keyDerivation.GetBytes(aes.BlockSize / 8);

            using (MemoryStream memoryStream = new MemoryStream())
            {
                using (CryptoStream cryptoStream = new CryptoStream(memoryStream, aes.CreateDecryptor(), CryptoStreamMode.Write))
                {
                    cryptoStream.Write(encryptedBytes, 0, encryptedBytes.Length);
                    cryptoStream.FlushFinalBlock();
                }

                byte[] decryptedBytes = memoryStream.ToArray();
                return Encoding.UTF8.GetString(decryptedBytes);
            }
        }
    }
}

使用示例：

string password = "myPassword123";
string plainText = "Hello, world!";

string encryptedText = EncryptionHelper.Encrypt(plainText, password);
string decryptedText = EncryptionHelper.Decrypt(encryptedText, password);

Console.WriteLine($"Encrypted Text: {encryptedText}");
Console.WriteLine($"Decrypted Text: {decryptedText}");
``