18 U.S.C. § 1704

Whoever steals, purloins, embezzles, or obtains by false pretense any key suited to any lock adopted by the Post Office Department or the Postal Service and in use on any of the mails or bags thereof, or any key to any lock box, lock drawer, or other authorized receptacle for the deposit or delivery of mail matter; or Whoever knowingly and unlawfully makes, forges, or counterfeits any such key, or possesses any such mail lock or key with the intent unlawfully or improperly to use, sell, or otherwise dispose of the same, or to cause the same to be unlawfully or improperly used, sold, or otherwise disposed of; or Whoever, being engaged as a contractor or otherwise in the manufacture of any such mail lock or key, delivers any finished or unfinished lock or the interior part thereof, or key, used or designed for use by the department, to any person not duly authorized under the hand of the Postmaster General and the seal of the Post Office Department or the Postal Service, to receive the same, unless the person receiving it is the contractor for furnishing the same or engaged in the manufacture thereof in the manner authorized by the contract, or the agent of such manufacturer— Shall be fined under this title or imprisoned not more than ten years, or both.