你可以这样显示它:

var strOriginal = richTextBox1.Text;

byte[] byt = System.Text.Encoding.ASCII.GetBytes(strOriginal);

// convert the byte array to a Base64 string
string strModified = Convert.ToBase64String(byt);

richTextBox1.Text = "" + strModified;

现在，把它转换回来。

var base64EncodedBytes = System.Convert.FromBase64String(richTextBox1.Text);

richTextBox1.Text = "" + System.Text.Encoding.ASCII.GetString(base64EncodedBytes);
MessageBox.Show("Done Converting! (ASCII from base64)");

我希望这能有所帮助!

编码

public static string Base64Encode(string plainText) {
  var plainTextBytes = System.Text.Encoding.UTF8.GetBytes(plainText);
  return System.Convert.ToBase64String(plainTextBytes);
}

解码

public static string Base64Decode(string base64EncodedData) {
  var base64EncodedBytes = System.Convert.FromBase64String(base64EncodedData);
  return System.Text.Encoding.UTF8.GetString(base64EncodedBytes);
}

有点像安德鲁。Fox回答，因为要解码的字符串可能不是一个正确的base64编码的字符串:

using System;

namespace Service.Support
{
    public static class Base64
    {
        public static string ToBase64(this System.Text.Encoding encoding, string text)
        {
            if (text == null)
            {
                return null;
            }

            byte[] textAsBytes = encoding.GetBytes(text);
            return Convert.ToBase64String(textAsBytes);
        }

        public static bool TryParseBase64(this System.Text.Encoding encoding, string encodedText, out string decodedText)
        {
            if (encodedText == null)
            {
                decodedText = null;
                return false;
            }

            try
            {
                byte[] textAsBytes = Convert.FromBase64String(encodedText);
                decodedText = encoding.GetString(textAsBytes);
                return true;
            }
            catch (Exception)
            {
                decodedText = null;
                return false;   
            }
        }
    }
}

// Encoding
string passw = "tes123";
var plainTextBytes = System.Text.Encoding.UTF8.GetBytes(passw);
string pass = System.Convert.ToBase64String(plainTextBytes);

// Normal
var encodedTextBytes = Convert.FromBase64String(pass);
string plainText = Encoding.UTF8.GetString(encodedTextBytes);

URL安全的Base64编码/解码

public static class Base64Url
{
    public static string Encode(string text)
    {
        return Convert.ToBase64String(Encoding.UTF8.GetBytes(text)).TrimEnd('=').Replace('+', '-')
            .Replace('/', '_');
    }

    public static string Decode(string text)
    {
        text = text.Replace('_', '/').Replace('-', '+');
        switch (text.Length % 4)
        {
            case 2:
                text += "==";
                break;
            case 3:
                text += "=";
                break;
        }
        return Encoding.UTF8.GetString(Convert.FromBase64String(text));
    }
}

你可以这样显示它:

var strOriginal = richTextBox1.Text;

byte[] byt = System.Text.Encoding.ASCII.GetBytes(strOriginal);

// convert the byte array to a Base64 string
string strModified = Convert.ToBase64String(byt);

richTextBox1.Text = "" + strModified;

现在，把它转换回来。

var base64EncodedBytes = System.Convert.FromBase64String(richTextBox1.Text);

richTextBox1.Text = "" + System.Text.Encoding.ASCII.GetString(base64EncodedBytes);
MessageBox.Show("Done Converting! (ASCII from base64)");

我希望这能有所帮助!