I'm trying to convert this piece of code from PHP to C#. It's part of a Captive Portal. Could somebody explain what it does?
$hexchal = pack ("H32", $challenge);
if ($uamsecret) {
$newchal = pack ("H*", md5($hexchal . $uamsecret));
} else {
$newchal = $hexchal;
}
$response = md5("\0" . $password . $newchal);
$newpwd = pack("a32", $password);
$pappassword = implode ("", unpack("H32", ($newpwd ^ $newchal)));
I also encountered the need of php's pack-unpack functions in c# but did not get any good resource.
So i thought to do it myself. I have verified the function's input with pack/unpack/md5 methods found at onlinephpfunctions.com. Since i have done code only as per my requirements. This can be extended for other formats
Pack
private static string pack(string input)
{
//only for H32 & H*
return Encoding.Default.GetString(FromHex(input));
}
public static byte[] FromHex(string hex)
{
hex = hex.Replace("-", "");
byte[] raw = new byte[hex.Length / 2];
for (int i = 0; i < raw.Length; i++)
{
raw[i] = Convert.ToByte(hex.Substring(i * 2, 2), 16);
}
return raw;
}
MD5
private static string md5(string input)
{
byte[] asciiBytes = Encoding.Default.GetBytes(input);
byte[] hashedBytes = MD5CryptoServiceProvider.Create().ComputeHash(asciiBytes);
string hashedString = BitConverter.ToString(hashedBytes).Replace("-", "").ToLower();
return hashedString;
}
Unpack
private static string unpack(string p1, string input)
{
StringBuilder output = new StringBuilder();
for (int i = 0; i < input.Length; i++)
{
string a = Convert.ToInt32(input[i]).ToString("X");
output.Append(a);
}
return output.ToString();
}
Eduardo,
if you take a look at the pack manual, pack is used to convert a string in (hex, octal, binary )to his number representation.
so
$hexcal = pack('H32', $challenge);
would convert a string like 'cca86bc64ec5889345c4c3d8dfc7ade9' to the actual 0xcca... de9
if $uamsecret exist do the same things with the MD5 of hexchal concacteate with the uamsecret.
if ($uamsecret) {
$newchal = pack ("H*", md5($hexchal . $uamsecret));
} else {
$newchal = $hexchal;
}
$response = md5("\0" . $password . $newchal);
MD% '\0' + $password + $newchal
$newpwd = pack("a32", $password);
pad password to 32 byte
$pappassword = implode ("", unpack("H32", ($newpwd ^ $newchal)));
do a xor newpwd and newchal and convert it to a hexadecimal string, I don't get the implode() maybe it's to convert to string to an array of character.
