public static string DecipherWithVersion(string cipher, string cipherVersion)
{
string jsUrl = string.Format("http://s.ytimg.com/yts/jsbin/player-{0}.js", cipherVersion);
string js = HttpHelper.DownloadString(jsUrl);
//Find "C" in this: var A = B.sig||C (B.s)
string functNamePattern = @"\""signature"",\s?([a-zA-Z0-9\$]+)\("; //Regex Formed To Find Word or DollarSign
var funcName = Regex.Match(js, functNamePattern).Groups[1].Value;
if (funcName.Contains("$"))
{
funcName = "\\" + funcName; //Due To Dollar Sign Introduction, Need To Escape
}
string funcPattern = @"(?!h\.)" + @funcName + @"=function\(\w+\)\{.*?\}"; //Escape funcName string
var funcBody = Regex.Match(js, funcPattern, RegexOptions.Singleline).Value; //Entire sig function
var lines = funcBody.Split(';'); //Each line in sig function
string idReverse = "", idSlice = "", idCharSwap = ""; //Hold name for each cipher method
string functionIdentifier = "";
string operations = "";
foreach (var line in lines.Skip(1).Take(lines.Length - 2)) //Matches the funcBody with each cipher method. Only runs till all three are defined.
{
if (!string.IsNullOrEmpty(idReverse) && !string.IsNullOrEmpty(idSlice) &&
!string.IsNullOrEmpty(idCharSwap))
{
break; //Break loop if all three cipher methods are defined
}
functionIdentifier = GetFunctionFromLine(line);
string reReverse = string.Format(@"{0}:\bfunction\b\(\w+\)", functionIdentifier); //Regex for reverse (one parameter)
string reSlice = string.Format(@"{0}:\bfunction\b\([a],b\).(\breturn\b)?.?\w+\.", functionIdentifier); //Regex for slice (return or not)
string reSwap = string.Format(@"{0}:\bfunction\b\(\w+\,\w\).\bvar\b.\bc=a\b", functionIdentifier); //Regex for the char swap.
if (Regex.Match(js, reReverse).Success)
{
idReverse = functionIdentifier; //If def matched the regex for reverse then the current function is a defined as the reverse
}
if (Regex.Match(js, reSlice).Success)
{
idSlice = functionIdentifier; //If def matched the regex for slice then the current function is defined as the slice.
}
if (Regex.Match(js, reSwap).Success)
{
idCharSwap = functionIdentifier; //If def matched the regex for charSwap then the current function is defined as swap.
}
}
foreach (var line in lines.Skip(1).Take(lines.Length - 2))
{
Match m;
functionIdentifier = GetFunctionFromLine(line);
if ((m = Regex.Match(line, @"\(\w+,(?<index>\d+)\)")).Success && functionIdentifier == idCharSwap)
{
operations += "w" + m.Groups["index"].Value + " "; //operation is a swap (w)
}
if ((m = Regex.Match(line, @"\(\w+,(?<index>\d+)\)")).Success && functionIdentifier == idSlice)
{
operations += "s" + m.Groups["index"].Value + " "; //operation is a slice
}
if (functionIdentifier == idReverse) //No regex required for reverse (reverse method has no parameters)
{
operations += "r "; //operation is a reverse
}
}
operations = operations.Trim();
return(DecipherWithOperations(cipher, operations));
}
