How to make inapp purchase using MKStoreKit 4.x receipt secure from being modified? <p>I have been storing inapp purchase receipt string in nsuserdefaults or a custom plist .This string used to determine the version of the app as full or limited.But how to make it secure.If any person modify this string by modifying the plist the app will change to full version rite.Then i came to know about keychains,but i am not able to understand how it works..is it a separate place where the string is saved or is it encrypting the string and saving it in plist..If anybody knows how to save inapp receipts from mkstorekit using keychains please share it here.. and also the keychains concept</p>