HOTP Devices

class HOTPDevice(TimestampMixin, ThrottlingMixin, Device):
    """
    HMAC-based OTP device following RFC 4226.
    
    Fields:
    - key: CharField(max_length=80) - Hex-encoded secret key
    - digits: PositiveSmallIntegerField - Number of digits (6 or 8)
    - tolerance: PositiveSmallIntegerField(default=5) - Counter tolerance
    - counter: BigIntegerField(default=0) - Next counter value
    """
    
    key = models.CharField(max_length=80, validators=[hex_validator()])
    digits = models.PositiveSmallIntegerField(choices=[(6, 6), (8, 8)], default=6)
    tolerance = models.PositiveSmallIntegerField(default=5)
    counter = models.BigIntegerField(default=0)
    
    @property
    def bin_key(self) -> bytes:
        """Secret key as binary string."""
    
    @property
    def config_url(self) -> str:
        """Configuration URL for QR codes and authenticator apps."""
    
    def verify_token(self, token) -> bool:
        """
        Verify HOTP token and advance counter.
        
        Parameters:
        - token: str - Token to verify
        
        Returns:
        bool - True if token is valid
        """
    
    def get_throttle_factor(self) -> int:
        """Return throttle factor from settings."""

class HOTPDeviceAdmin(admin.ModelAdmin):
    """Admin interface for HOTPDevice with QR code support."""
    
    def qrcode_link(self, device):
        """Generate QR code link for device configuration."""
    
    def config_view(self, request, pk):
        """Configuration view showing device setup information."""
    
    def qrcode_view(self, request, pk):
        """QR code image view for device setup."""

from django_otp.plugins.otp_hotp.models import HOTPDevice

# Create HOTP device
device = HOTPDevice.objects.create(
    user=user,
    name='Hardware Token',
    tolerance=10,  # Allow up to 10 counter values ahead
    digits=8       # 8-digit tokens
)

print(f"Initial counter: {device.counter}")
print(f"Setup URL: {device.config_url}")

def verify_hotp_with_info(device, token):
    """Verify HOTP token and return verification info."""
    
    old_counter = device.counter
    is_valid = device.verify_token(token)
    
    return {
        'valid': is_valid,
        'old_counter': old_counter,
        'new_counter': device.counter,
        'counter_advanced': device.counter - old_counter
    }

# Usage
result = verify_hotp_with_info(device, '123456')
if result['valid']:
    print(f"Counter advanced by {result['counter_advanced']}")

# settings.py
OTP_HOTP_THROTTLE_FACTOR = 1  # Throttling factor
OTP_HOTP_ISSUER = "My Company"  # Issuer for QR codes