how to protect IN-APP from hacking with "Freedom"

Solar2D Monetization (in-app purchases, ads, etc.)
#1

Hello!

We try to protect Google in-app from hacking with Freedom under root.

Here is link to GUIDE:

https://docs.coronalabs.com/guide/monetization/IAP/index.html

Here is quote frome guide:

local function storeTransaction( event )
local transaction = event.transaction
if ( transaction.state == “purchased” ) then
–handle a successful transaction here
print( “productIdentifier”, transaction.productIdentifier )
print( “receipt”, transaction.receipt )
print( “signature:”, transaction.signature )
print( “transactionIdentifier”, transaction.identifier )
print( “date”, transaction.date )
elseif ( transaction.state == “cancelled” ) then
–handle a cancelled transaction here
elseif ( transaction.state == “failed” ) then
–handle a failed transaction here
end
–tell the store that the transaction is complete!
–if you’re providing downloadable content, do not call this until the download has completed
store.finishTransaction( event.transaction )
end

Next quote:

  • signature — a digital signature string that can be used to verify the purchase. This is the inapp_signature returned by Google Play.

So, we get a signature - how i knowed, it is json table, hashed with our google private key. So, i should prepare json string and hash it with some algorithm and our developer key, then compare result and signature from listener.

Questions are:

  • how to prepare this json string?

  • which algorithm i need for hashing?

  • Is it some tutorial about these actions on Corona?

Thanks!