Export your StoreKit testing certificate
Export the public root certificate from your StoreKit configuration file in Xcode so Voidhash can verify transactions made in the local StoreKit testing environment.
The StoreKit testing framework (.cer certificate) is the public root certificate that Xcode's
local StoreKit testing environment uses to sign receipts and transactions. Voidhash needs it
because local test purchases are signed with a different key than Sandbox and Production (which
use the Apple Inc. Root certificate). You export it as a .cer file from your .storekit
configuration file in Xcode and upload that file to Voidhash.
Create a StoreKit configuration file (if you don't have one)
In Xcode, choose File → New → File from Template. Type storekit in the Filter field, select
StoreKit Configuration File, click Next, and save it into your project. The test
certificate is derived from this file.
Select the .storekit file in the Project navigator
In Xcode's Project navigator (left sidebar), click the StoreKit configuration file so it is the active item. The Save Public Certificate command is only available when the configuration file is selected.
Choose Editor → Save Public Certificate
From the Xcode menu bar, choose Editor → Save Public Certificate, then select a location in your project and save the file. Apple doesn't prescribe a folder or filename, so you can name it anything.
It's a root certificate
The test environment's certificate is a root certificate, so there's no certificate chain to validate when verifying the receipt signature.
Upload the .cer to Voidhash
Upload the exported .cer file into the StoreKit testing framework (.cer certificate) field
in Voidhash.
Local testing only
This certificate verifies only transactions and receipts produced by Xcode's local StoreKit testing environment. Those receipts aren't signed by the App Store and aren't valid in Sandbox or Production, which use the Apple Inc. Root certificate.