The bonds may be secured by a trust indenture between the council and a corporate trustee which may be either a bank having the power of a trust company or a trust company. Such trust indenture may contain reasonable provisions for protecting and enforcing the rights and remedies of the bondholders, including covenants setting forth the duties of the council in relation to the exercise of its powers and the custody and use of the money. The council may provide by the trust indenture for the payment of the proceeds of the bonds and the revenue to the trustee under the trust indenture or other depository and for disbursement with safeguards as the council determines are necessary.