If, in the opinion of the Treasurer, any bonds issued by the commission under this title are adequately secured and the revenues and other funds applicable to the payments of the bonds are, or upon the acquisition, construction, or improvement of the project or projects which the bonds finance, will be sufficient to pay the principal of and interest on the bonds, the Treasurer shall certify that the bonds are legal investments for all trust funds, the funds of all insurance companies, banks (both commercial and savings), trust companies, savings and loan associations, and investment companies, for executors, administrators, guardians, conservators, trustees, and other fiduciaries, for state school funds, and for any funds which may be invested in county, municipal, or school district bonds, and that the bonds are 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, including deposits to secure public funds.