CheckoutVerifier

CheckoutVerifier helps you Verify your In-App Purchase receipts & protect your Apps from hacking, patching used by Piracy Apps like Lucky Patcher.
Since I was using these classes in every project, the Copy/Pasting of classes was annoying so thought of releasing it as a library which might be of help to others too!

How does it work?

Well, the library sends the Signed Json Response & Signature that you receive after a purchase is completed on a specified server url where it checks the signature of that response data with your BASE64 Key provided to you in your Developer Console.

Set Up

* Get Licensing API Key

Navigate to Developer Console & Select your App.
Go to Development Tools > Services & API.
Copy the BASE64 Licensing Key

* Creating a Verifying PHP File

Just a create a File & name it as verify.php or anything you want.
Paste the following code in it & Upload it to your server.

<?php
// get jsonResponse
$data = $_GET['data'];

// get signature
$signature = $_GET['signature'];

// get key
$key_64 = "YOUR BASE64 KEY THAT YOU GOT FROM DEVELOPER CONSOLE, THERE SHOULD BE NO SPACES!";


$key =  "-----BEGIN PUBLIC KEY-----\n".
        chunk_split($key_64, 64,"\n").
        '-----END PUBLIC KEY-----';

//using PHP to create an RSA key
$key = openssl_get_publickey($key);


// state whether signature is okay or not
$ok = openssl_verify($data, base64_decode($signature), $key, OPENSSL_ALGO_SHA1);
if ($ok == 1) {
    echo "verified";
} elseif ($ok == 0) {
    echo "unverified";
} else {
    die ("fault, error checking signature");
}

// free the key from memory
openssl_free_key($key);

?>

* Implementing Library (Gradle)

Latest_Version:

dependencies {
    implementation 'com.lazygeniouz:checkout-verifier:Latest_Version'
}

* CheckOutVerifier

Just pass on the required fields in the Constructor & call start();
Example:
Java

new CheckoutVerifier(url, jsonResponse, signature, new VerifyingListener() {
            @Override
            public void onVerificationStarted() {
                //Show a ProgressDialog or something
            }

            @Override
            public void onVerificationCompleted(boolean isVerified) {
                //Check if the Purchase is Valid...
                //Consume if not!
            }

            @Override
            public void onExceptionCaught(@NotNull Exception exception) {
                //Called when there was an error connecting to Server.
            }
        }).start();

Kotlin

CheckoutVerifier(url, jsonResponse, signature, object : VerifyingListener {
            override fun onVerificationStarted() {}

            override fun onVerificationCompleted(isVerified: Boolean) {}

            override fun onExceptionCaught(exception: Exception) {}
        }).start()