如何解码base64编码的字符串?

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:

  1. 原始字符串首先通过以下代码传递:

    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());
}

    代码中的p1部分应该是字符串"_p0lizei.".

  2. 然后通过以下代码将其转换为Base64字符串:

    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;
}

The question is, how do I decode the Base64 string so that I can find out what the original string is?

459342 次浏览
小开

简单:

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

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..."

将return m0001cd(builder3.ToString());改为return builder3.ToString();。

小开 
    // 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);
}

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