import secrets


def secret_sequence(num, sequence):
    """Creates a random sequence (cryptographically strong random sequence).

    Randomly chooses num elements from sequence and returns the random sequence as a string.

    Args:
        num (int): The length of the output sequence.
        sequence (str): The elements to choose from as a string, each char one possible option.

    Returns:
        str: The random sequence as a string (num random elements from sequence combined).
    """
    return ''.join(secrets.choice(sequence) for _ in range(num))