|
|
@@ -0,0 +1,82 @@
|
|
|
+using System;
|
|
|
+using System.Linq;
|
|
|
+using System.Security.Cryptography;
|
|
|
+
|
|
|
+namespace InABox.Core
|
|
|
+{
|
|
|
+ public static class Authenticator
|
|
|
+ {
|
|
|
+
|
|
|
+ public static readonly int CODE_LENGTH = 6;
|
|
|
+
|
|
|
+ private static readonly int CODE_MODULO = (int)Math.Pow(10, CODE_LENGTH);
|
|
|
+
|
|
|
+ private static byte[] FromHexString(string hex) {
|
|
|
+ if (hex.Length % 2 == 1)
|
|
|
+ throw new Exception("The binary key cannot have an odd number of digits");
|
|
|
+
|
|
|
+ byte[] arr = new byte[hex.Length >> 1];
|
|
|
+
|
|
|
+ for (int i = 0; i < hex.Length >> 1; ++i)
|
|
|
+ {
|
|
|
+ arr[i] = (byte)((GetHexVal(hex[i << 1]) << 4) + (GetHexVal(hex[(i << 1) + 1])));
|
|
|
+ }
|
|
|
+
|
|
|
+ return arr;
|
|
|
+ }
|
|
|
+
|
|
|
+ public static int GetHexVal(char hex) {
|
|
|
+ int val = (int)hex;
|
|
|
+ //For uppercase A-F letters:
|
|
|
+ //return val - (val < 58 ? 48 : 55);
|
|
|
+ //For lowercase a-f letters:
|
|
|
+ //return val - (val < 58 ? 48 : 87);
|
|
|
+ //Or the two combined, but a bit slower:
|
|
|
+ return val - (val < 58 ? 48 : (val < 97 ? 55 : 87));
|
|
|
+ }
|
|
|
+
|
|
|
+ public static string GenerateGoogleAuthenticatorCode(byte[] key)
|
|
|
+ {
|
|
|
+ var _time = DateTimeOffset.Now.ToUnixTimeSeconds();
|
|
|
+ return GenerateGoogleAuthenticatorCode(_time, key);
|
|
|
+ }
|
|
|
+
|
|
|
+ private static string GenerateGoogleAuthenticatorCode(long time, byte[] key)
|
|
|
+ {
|
|
|
+ var _window = time / 30;
|
|
|
+ var _hex = _window.ToString("x");
|
|
|
+ if (_hex.Length < 16)
|
|
|
+ {
|
|
|
+ _hex = _hex.PadLeft(16, '0');
|
|
|
+ }
|
|
|
+ var _bytes = FromHexString(_hex);
|
|
|
+ var _hash = new HMACSHA1(key).ComputeHash(_bytes);
|
|
|
+
|
|
|
+ var _offset = _hash.Last() & 0xf;
|
|
|
+ var _selected = new byte[4];
|
|
|
+ Buffer.BlockCopy(_hash, _offset, _selected, 0, 4);
|
|
|
+ if (BitConverter.IsLittleEndian)
|
|
|
+ {
|
|
|
+ Array.Reverse(_selected);
|
|
|
+ }
|
|
|
+
|
|
|
+ var _integer = BitConverter.ToInt32(_selected, 0);
|
|
|
+ var _truncated = _integer & 0x7fffffff;
|
|
|
+
|
|
|
+ return (_truncated % CODE_MODULO).ToString().PadLeft(CODE_LENGTH, '0');
|
|
|
+ }
|
|
|
+
|
|
|
+ public static bool CheckAuthenticationCode(byte[] key, string code)
|
|
|
+ {
|
|
|
+ var _time = DateTimeOffset.Now.ToUnixTimeSeconds();
|
|
|
+ for (long _l = _time - 30; _l <= _time; _l += 30)
|
|
|
+ {
|
|
|
+ if(GenerateGoogleAuthenticatorCode(_l, key) == code)
|
|
|
+ {
|
|
|
+ return true;
|
|
|
+ }
|
|
|
+ }
|
|
|
+ return false;
|
|
|
+ }
|
|
|
+ }
|
|
|
+}
|
frankvandenbos