California Code, Public Contract Code - PCC § 10304

All bids shall be sealed and shall be publicly opened and read at the time set forth in the solicitation, provided any person present desires the bids to be so read. No bids shall be considered which have not been received in the office of the department prior to the closing time for bids set forth in the invitations to bids. The department shall maintain confidentiality regarding each bid until the public opening and reading takes place.