Twofactor authentication and strong password

application/libraries/TwoFactorAuth.php

@@ -0,0 +1,193 @@
+<?php
+defined('BASEPATH') OR exit('No direct script access allowed');
+
+/**
+ * Two-Factor Authentication Library
+ * Implements TOTP (Time-based One-Time Password) for Google Authenticator
+ * Based on RFC 6238
+ */
+class TwoFactorAuth
+{
+    protected $ci;
+    protected $codeLength = 6;
+    protected $period = 30; // 30 seconds validity window
+
+    public function __construct()
+    {
+        $this->ci =& get_instance();
+    }
+
+    /**
+     * Generate a new secret key for TOTP
+     * @return string Base32 encoded secret
+     */
+    public function generateSecret($length = 16)
+    {
+        $secret = '';
+        $validChars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ234567'; // Base32 alphabet
+
+        for ($i = 0; $i < $length; $i++) {
+            $secret .= $validChars[random_int(0, 31)];
+        }
+
+        return $secret;
+    }
+
+    /**
+     * Generate QR code URL for Google Authenticator
+     * @param string $secret The user's TOTP secret
+     * @param string $username The username
+     * @param string $issuer The application name
+     * @return string QR code URL
+     */
+    public function getQRCodeUrl($secret, $username, $issuer = 'DBOIS')
+    {
+        $encodedIssuer = rawurlencode($issuer);
+        $encodedUsername = rawurlencode($username);
+
+        $otpauthUrl = "otpauth://totp/{$encodedIssuer}:{$encodedUsername}?secret={$secret}&issuer={$encodedIssuer}";
+
+        // Using Google Charts API for QR code generation
+        return "https://chart.googleapis.com/chart?chs=200x200&chld=M|0&cht=qr&chl=" . urlencode($otpauthUrl);
+    }
+
+    /**
+     * Verify a TOTP code
+     * @param string $secret The user's secret
+     * @param string $code The code to verify
+     * @param int $discrepancy Time window (default 1 = +/- 30 seconds)
+     * @return bool True if code is valid
+     */
+    public function verifyCode($secret, $code, $discrepancy = 1)
+    {
+        $currentTimeSlice = floor(time() / $this->period);
+
+        for ($i = -$discrepancy; $i <= $discrepancy; $i++) {
+            $calculatedCode = $this->getCode($secret, $currentTimeSlice + $i);
+            if ($this->timingSafeEquals($calculatedCode, $code)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    /**
+     * Generate TOTP code for a given time slice
+     * @param string $secret The secret key
+     * @param int $timeSlice The time slice (defaults to current)
+     * @return string The generated code
+     */
+    public function getCode($secret, $timeSlice = null)
+    {
+        if ($timeSlice === null) {
+            $timeSlice = floor(time() / $this->period);
+        }
+
+        $secretKey = $this->base32Decode($secret);
+
+        // Pack time into binary string
+        $time = chr(0).chr(0).chr(0).chr(0).pack('N*', $timeSlice);
+
+        // Hash with secret
+        $hash = hash_hmac('sha1', $time, $secretKey, true);
+
+        // Use last 4 bits as offset
+        $offset = ord(substr($hash, -1)) & 0x0F;
+
+        // Get 4 bytes from offset
+        $hashPart = substr($hash, $offset, 4);
+
+        // Unpack binary value
+        $value = unpack('N', $hashPart);
+        $value = $value[1];
+
+        // Only 32 bits
+        $value = $value & 0x7FFFFFFF;
+
+        // Get the required digits
+        $modulo = pow(10, $this->codeLength);
+
+        return str_pad($value % $modulo, $this->codeLength, '0', STR_PAD_LEFT);
+    }
+
+    /**
+     * Decode Base32 string
+     * @param string $secret Base32 encoded string
+     * @return string Binary string
+     */
+    protected function base32Decode($secret)
+    {
+        if (empty($secret)) {
+            return '';
+        }
+
+        $base32chars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ234567';
+        $base32charsFlipped = array_flip(str_split($base32chars));
+
+        $paddingCharCount = substr_count($secret, '=');
+        $allowedValues = array(6, 4, 3, 1, 0);
+
+        if (!in_array($paddingCharCount, $allowedValues)) {
+            return false;
+        }
+
+        for ($i = 0; $i < 4; $i++) {
+            if ($paddingCharCount == $allowedValues[$i] &&
+                substr($secret, -($allowedValues[$i])) != str_repeat('=', $allowedValues[$i])) {
+                return false;
+            }
+        }
+
+        $secret = str_replace('=', '', $secret);
+        $secret = str_split($secret);
+        $binaryString = '';
+
+        for ($i = 0; $i < count($secret); $i = $i + 8) {
+            $x = '';
+            if (!in_array($secret[$i], $base32charsFlipped)) {
+                return false;
+            }
+
+            for ($j = 0; $j < 8; $j++) {
+                $x .= str_pad(base_convert(@$base32charsFlipped[@$secret[$i + $j]], 10, 2), 5, '0', STR_PAD_LEFT);
+            }
+
+            $eightBits = str_split($x, 8);
+
+            for ($z = 0; $z < count($eightBits); $z++) {
+                $binaryString .= (($y = chr(base_convert($eightBits[$z], 2, 10))) || ord($y) == 48) ? $y : '';
+            }
+        }
+
+        return $binaryString;
+    }
+
+    /**
+     * Timing-safe string comparison
+     * @param string $safeString Known string
+     * @param string $userString User provided string
+     * @return bool True if strings match
+     */
+    protected function timingSafeEquals($safeString, $userString)
+    {
+        if (function_exists('hash_equals')) {
+            return hash_equals($safeString, $userString);
+        }
+
+        $safeLen = strlen($safeString);
+        $userLen = strlen($userString);
+
+        if ($userLen != $safeLen) {
+            return false;
+        }
+
+        $result = 0;
+
+        for ($i = 0; $i < $userLen; $i++) {
+            $result |= (ord($safeString[$i]) ^ ord($userString[$i]));
+        }
+
+        return $result === 0;
+    }
+}