我试图“解码”下面的Base64字符串:

OBFZDTcPCxlCKhdXCQ0kMQhKPh9uIgYIAQxALBtZAwUeOzcdcUEeW0dMO1kbPElWCV1ISFFKZ0kdWFlLAURPZhEFQVseXVtPOUUICVhMAzcfZ14AVEdIVVgfAUIBWVpOUlAeaUVMXFlKIy9rGUN0VF08Oz1POxFfTCcVFw1LMQNbBQYWAQ==

这是我对字符串本身的了解:

The original string is first passed through the following code: private static string m000493(string p0, string p1) { StringBuilder builder = new StringBuilder(p0); StringBuilder builder2 = new StringBuilder(p1); StringBuilder builder3 = new StringBuilder(p0.Length); int num = 0; Label_0084: while (num < builder.Length) { int num2 = 0; while (num2 < p1.Length) { if ((num == builder.Length) || (num2 == builder2.Length)) { MessageBox.Show("EH?"); goto Label_0084; } char ch = builder[num]; char ch2 = builder2[num2]; ch = (char)(ch ^ ch2); builder3.Append(ch); num2++; num++; } } return m0001cd(builder3.ToString()); } The p1 part in the code is supposed to be the string "_p0lizei.". It is then converted to a Base64 string by the following code: private static string m0001cd(string p0) { string str2; try { byte[] buffer = new byte[p0.Length]; str2 = Convert.ToBase64String(Encoding.UTF8.GetBytes(p0)); } catch (Exception exception) { throw new Exception("Error in base64Encode" + exception.Message); } return str2; }

问题是,我如何解码Base64字符串以便我能找到原始字符串是什么?


简单:

byte[] data = Convert.FromBase64String(encodedString);
string decodedString = Encoding.UTF8.GetString(data);

m000493方法似乎执行某种XOR加密。这意味着可以使用相同的方法对文本进行编码和解码。你所要做的就是反转m0001cd:

string p0 = Encoding.UTF8.GetString(Convert.FromBase64String("OBFZDT..."));

string result = m000493(p0, "_p0lizei.");
//    result == "gaia^unplugged^Ta..."

返回m0001cd(builder3.ToString());改为返回builder3.ToString();。

    // Decode a Base64 string to a string
    public static string DecodeBase64(string value)
    {
        if(string.IsNullOrEmpty(value))
            return string.Empty;
        var valueBytes = System.Convert.FromBase64String(value);
        return System.Text.Encoding.UTF8.GetString(valueBytes);
    }