public static string GenerateSteamGuardCodeForTime(this SteamGuardData steamGuard, long time)
{
if (steamGuard.SharedSecret == null || steamGuard.SharedSecret.Length == 0)
{
return("");
}
string sharedSecretUnescaped = Regex.Unescape(steamGuard.SharedSecret);
byte[] sharedSecretArray = Convert.FromBase64String(sharedSecretUnescaped);
byte[] timeArray = new byte[8];
time /= 30L;
for (int i = 8; i > 0; i--)
{
timeArray[i - 1] = (byte)time;
time >>= 8;
}
HMACSHA1 hmacGenerator = new HMACSHA1();
hmacGenerator.Key = sharedSecretArray;
byte[] hashedData = hmacGenerator.ComputeHash(timeArray);
byte[] codeArray = new byte[5];
try
{
byte b = (byte)(hashedData[19] & 0xF);
int codePoint = (hashedData[b] & 0x7F) << 24 | (hashedData[b + 1] & 0xFF) << 16 | (hashedData[b + 2] & 0xFF) << 8 | (hashedData[b + 3] & 0xFF);
for (int i = 0; i < 5; ++i)
{
codeArray[i] = steamGuardCodeTranslations[codePoint % steamGuardCodeTranslations.Length];
codePoint /= steamGuardCodeTranslations.Length;
}
}
catch (Exception)
{
return(null); //Change later, catch-alls are bad!
}
return(Encoding.UTF8.GetString(codeArray));
}
public static string GenerateCode(this SteamGuardData guardData)
{
return(GenerateSteamGuardCodeForTime(guardData, SteamTime.GetSteamTime()));
}