C#使用随机数gen和密钥来解析加密消息，但我无法将消息保留在字符串内

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

class Program
{
    static void Main()
    {
        string encryptedMessage = "encrypted message"; // 加密后的消息
        byte[] key = GenerateKey(); // 生成密钥
        byte[] decryptedBytes = DecryptMessage(encryptedMessage, key); // 解密消息

        // 将解密后的字节数组转换为字符串
        string decryptedMessage = Encoding.UTF8.GetString(decryptedBytes);

        Console.WriteLine("Decrypted Message: " + decryptedMessage);
    }

    static byte[] GenerateKey()
    {
        byte[] key = new byte[16]; // 生成16字节的密钥
        using (var rng = new RNGCryptoServiceProvider())
        {
            rng.GetBytes(key);
        }
        return key;
    }

    static byte[] DecryptMessage(string encryptedMessage, byte[] key)
    {
        byte[] encryptedBytes = Convert.FromBase64String(encryptedMessage);

        using (var aes = Aes.Create())
        {
            aes.Key = key;
            aes.Mode = CipherMode.ECB; // 使用ECB模式解密
            aes.Padding = PaddingMode.PKCS7;

            using (var decryptor = aes.CreateDecryptor())
            {
                return decryptor.TransformFinalBlock(encryptedBytes, 0, encryptedBytes.Length);
            }
        }
    }
}