Indiana does allow someone with an international driver's license and a valid social security number to buy a car. Once you have taken ownership of the vehicle you will need to register and title it in Indiana.

To obtain vehicle registration in IN you must go to a license office and provide: Certificate of Origin, Proof of Insurance, Verification of Social Security Number and Proof that the vehicle you are registering passed a vehicle emissions test if you live in specific counties.

If you are registering a used vehicle you will instead need to provide a properly assigned vehicle title, proof of current vehicle insurance and verification of your social security number.

You will also need to apply for a title for the vehicle. You will need different documents depending on if the vehicle you purchased is new or used. They again verify your SSN during the titling process.

As for finding insurance for a vehicle, it will be difficult with your foreign license. If you obtain a US license from Indiana, it will be easier to find an insurance coverage. Many insurance companies will allow you to start a policy and give you 30 days or so to obtain a US license. You can start here to get a quote for car insurance online.