import secrets


def calculate_jittered_interval(base_interval: int, jitter_percentage: float) -> float:
    """Calculates a jittered interval based on the base interval and jitter percentage.

    Args:
        base_interval: The base interval in seconds.
        jitter_percentage: The jitter percentage as a float (e.g., 0.1 for 10%).

    Returns:
        The jittered interval in seconds.
    """
    if not (0 <= jitter_percentage <= 1):
        raise ValueError("Jitter percentage must be between 0 and 1.")

    offset_range = jitter_percentage * base_interval / 2
    offset = secrets.SystemRandom().uniform(-offset_range, offset_range)
    return base_interval + offset