Is it permissible to work in a printing house that prints cigarette packs, knowing that the nature of my work requires me to sign off on and authenticate the quality of these products?

Printing cigarette boxes is a form of cooperation in sin and aggression. Smoking is forbidden due to proven harm, so assisting in it is not permissible except in a case of necessity where a person reaches a point where, if they do not consume the forbidden item, they will perish or come close to perishing.