如何在c#中获取带UFTC印章的今天日期？

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

public string GetUFTCStampedDate()
{
    // 获取当前日期
    DateTime today = DateTime.Today;

    // 将日期转换为字符串
    string dateString = today.ToString("yyyy-MM-dd");

    // 创建一个SHA256哈希算法实例
    using (SHA256 sha256 = SHA256.Create())
    {
        // 将日期字符串转换为字节数组
        byte[] dateBytes = Encoding.UTF8.GetBytes(dateString);

        // 计算日期的哈希值
        byte[] hashBytes = sha256.ComputeHash(dateBytes);

        // 将哈希值转换为Base64字符串
        string hashString = Convert.ToBase64String(hashBytes);

        // 将Base64字符串添加到日期字符串中
        string stampedDate = dateString + " UFTC:" + hashString;

        // 返回带UFTC印章的日期字符串
        return stampedDate;
    }
}

string stampedDate = GetUFTCStampedDate();
Console.WriteLine(stampedDate);