feat: Add QR code payload generation for TOTP

README.md

@@ -17,6 +17,7 @@ For a secure installation you have to make sure that used codes cannot be reused
 - Built-in validation methods.
 - Secret key generation for TOTP.
 - Compatible with Google Authenticator and similar apps.
+- Generate QR code payloads for easy integration with TOTP applications.
 
 ## Installation
 
@@ -67,6 +68,18 @@ $secret = $ga->createSecret();
 echo "Your secret key is: " . $secret;
 ```
 
+### Generating a QR Code Payload
+
+To generate a QR code payload for a TOTP secret, use the `getQrCodePayload` function:
+
+```php
+$label = '[email protected]'; // The user's email or username
+$issuer = 'MyApp'; // Optional issuer name
+
+$qrcodePayload = $totp->getQrCodePayload($secret, $label, $issuer);
+echo "QR Code Payload: " . $qrcodePayload . "\n";
+```
+
 ### Validating a TOTP Code
 
 You can validate a TOTP code using the `verifyCode` method:

src/Base32.php

@@ -70,40 +70,12 @@ public function _base32Decode($secret)
      */
     public function _getBase32LookupTable()
     {
-        return array(
-            'A',
-            'B',
-            'C',
-            'D',
-            'E',
-            'F',
-            'G',
-            'H', //  7
-            'I',
-            'J',
-            'K',
-            'L',
-            'M',
-            'N',
-            'O',
-            'P', // 15
-            'Q',
-            'R',
-            'S',
-            'T',
-            'U',
-            'V',
-            'W',
-            'X', // 23
-            'Y',
-            'Z',
-            '2',
-            '3',
-            '4',
-            '5',
-            '6',
-            '7', // 31
+        return [
+            'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', //  7
+            'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', // 15
+            'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', // 23
+            'Y', 'Z', '2', '3', '4', '5', '6', '7', // 31
             '=',  // padding char
-        );
+        ];
     }
 }

src/Totp.php

@@ -45,6 +45,26 @@ public function createSecret(int $secretLength = 16): string
         return $secret;
     }
 
+    /**
+     * Generate a QR code payload for the given secret.
+     *
+     * @param string $secret The TOTP secret.
+     * @param string $label The label for the account (e.g., email, username).
+     * @param string|null $issuer Optional issuer name for the TOTP app.
+     *
+     * @return string The QR code payload.
+     */
+    public function getQrCodePayload(string $secret, string $label, ?string $issuer = null): string
+    {
+        $payload = 'otpauth://totp/' . $label . '?secret=' . $secret;
+
+        if ($issuer) {
+            $payload .= '&issuer=' . $issuer;
+        }
+
+        return $payload;
+    }
+
     /**
      * Calculate the code, with given secret and point in time.
      *

tests/TotpTest.php

@@ -36,6 +36,20 @@ public function testCreateSecretInvalidLengthThrowsException()
         $this->totp->createSecret(10);  // Invalid length less than 16
     }
 
+    public function testGetQrCodePayload()
+    {
+        $secret = $this->totp->createSecret();
+        $label = '[email protected]';
+        $issuer = 'MyApp';
+
+        $payload = $this->totp->getQrCodePayload($secret, $label, $issuer);
+
+        $this->assertStringStartsWith('otpauth://totp/', $payload);
+        $this->assertStringContainsString('totp/' . $label, $payload);
+        $this->assertStringContainsString('issuer=' . $issuer, $payload);
+        $this->assertStringContainsString('secret=' . $secret, $payload);
+    }
+
     public function testGetCode()
     {
         $secret = $this->totp->createSecret();