Indiana Code Title 32. Property § 32-21-1-10

Sec. 10. A contract for the payment of any sum of money or thing of value, as a commission or reward for the finding or procuring by one (1) person of a purchaser for the real estate of another, is not valid unless the contract is in writing and signed by the owner of the real estate or the owner's legally appointed and duly qualified representative.  For purposes of this section, any general reference to the real estate that is sufficient to identify the real estate is a sufficient description of the real estate.