Ind. Code § 5-20-2-10
The bonds and any coupons shall bear the manual or facsimile signatures of the executive officer and the recording officer of the county or municipality and any coupons shall bear the facsimile signature of one (1) or more of these officers. These signatures shall be the valid and binding signatures of these officers, notwithstanding that before delivery and payment, any or all of the individuals whose signatures appear have ceased to be officers of the county or municipality issuing the bonds. The validity of the bonds is not dependent on nor affected by the validity or regularity of any proceedings relating to the home mortgages for which the bonds are issued. The ordinance authorizing the bonds may provide that the bonds shall contain a recital that they are issued pursuant to this chapter, which recital shall be conclusive evidence of their validity and of the regularity of their issuance.
IC 5-20-2-10