(a) It is hereby determined that the purposes of sections 15-31a to 15-31i, inclusive, are public purposes and that the authority will be performing an essential governmental function in the exercise of the powers conferred upon it hereunder. The state covenants with the purchasers and all subsequent holders and transferees of notes and bonds issued by the authority under sections 15-31c to 15-31f, inclusive, in consideration of the acceptance of and payment for the notes and bonds, that the principal and interest of such notes and bonds shall at all times be free from taxation, except for estate and gift taxes, imposed by the state or by any political subdivision thereof but the interest on such notes and bonds shall be included in the computation of any excise or franchise tax. The authority is authorized to include this covenant of the state in any agreement with the holder of such notes or bonds. Any notes or bonds issued by the authority pursuant to sections 15-31c to 15-31f, inclusive, may be issued on a basis that provides that the interest thereon is intended to be exempt or not to be exempt from federal income taxation, as may be determined by the authority.

(b) Bonds issued under the authority of sections 15-31c to 15-31f, inclusive, are hereby made securities in which all public officers and public bodies of the state and its political subdivisions, all insurance companies, credit unions, building and loan associations, investment companies, banking associations, trust companies, executors, administrators, trustees and other fiduciaries and pension, profit-sharing and retirement funds may properly and legally invest funds, including capital in their control or belonging to them. Such bonds are hereby made securities which may properly and legally be deposited with and received by any state or municipal officer or any agency or political subdivision of the state for any purpose for which the deposit of bonds or obligations of the state is now or may hereafter be authorized by law.