Any member of the board of aldermen or officer of the city who shall, in official capacity, or under color of his office, knowingly or willfully or corruptly vote or assent to, or report in favor of or allow or certify for allowance, any claim or demand against the city, which claim or demand shall be on account of or under color of a contract or agreement not authorized by law and the ordinances of the city, shall be deemed guilty of a misdemeanor, and shall, upon conviction thereof, be punished by imprisonment in the county jail for not more than one year or by a fine not exceeding five hundred dollars, or by both such fine and imprisonment.