Anticheat methods

Recommended sequence of actions when working with transactions

1. Get response about a completed transaction from the payment system.

2. Either send data about the received transaction for verification by calling devtodev anti-cheat methods or use your own tools for transaction verification.

3. If the transaction has successfully passed verification, perform the Payment event. If the transaction has not passed verification, do not perform the Payment event.

Payment Validation

The devtodev service allows you to validate transactions to prevent fraud from influencing your statistics. For this, you need to integrate DTDAntiCheat module.

We strongly discourage you from using verification results for deciding on allowing or denying users to receive their purchases! We do not recommend to mark users as cheaters based on the results of this verification! Employ this method exclusively for preventing fraud transaction data from being sent to devtodev!

App Store (iOS) Swift

To validate the transaction you can use the verifyPayment(completionHandler: @escaping (DTDVerifyResponse) -> Void) method immediately during the transaction processing, e.g.:

extension Purchases: SKPaymentTransactionObserver {
    func paymentQueue(_ queue: SKPaymentQueue, updatedTransactions transactions: [SKPaymentTransaction]) {
        for transaction in transactions {
            switch transaction.transactionState {
                case .purchased:
                    DTDAntiCheat.verifyPayment { response in
                            switch response.receiptStatus {
                                case .receiptInternalError: 
                                  // your code
                                  break
                                case .receiptValid:
                                  // your code
                                  break
                                case .receiptSandbox:
                                  // your code
                                  break
                                case .receiptServerError:
                                  // your code
                                  break
                                case .receiptNotValid: 
                                  // your code
                                  break
                                @unknown default: break
                            }
                            SKPaymentQueue.default().finishTransaction(transaction)
                        }

                case .restored:
                    SKPaymentQueue.default().finishTransaction(transaction)

                case .failed:
                    SKPaymentQueue.default().finishTransaction(transaction)

                default:
                    break
            }
        }
    }
}

DTDVerifyResponse

The DTDVerifyResponse object returned while validating the transaction has two properties:

Property	Description
receiptStatus	Enum type DTDReceiptStatus that represents the result of the transaction validation.
verificationResult	Additional information from the validation server.

DTDReceiptStatus

The enum type returned as a result of validation can receive the following values:

Value	Description
receiptValid	The payment is valid, the transaction is genuine.
receiptNotValid	The payment is invalid, the transaction may be a duplicate or fraud.
receiptServerError	Server error when validating the payment.
receiptSandbox	Test payment.
receiptInternalError	Internal SDK error.

We recommend calling the Real Currency Payment method in all cases except when you receive receiptNotValid or receiptSandbox as a result of the validation.

App Store (iOS) Objective-C

To validate the transaction you can use the (void)verifyPaymentCompletion:( void (^ _Nonnull)(DTDVerifyResponse * _Nonnull))completionHandler; method immediately during the transaction processing, e.g.:

- (void)paymentQueue:(SKPaymentQueue *)queue updatedTransactions:(NSArray *)transactions{
    for(SKPaymentTransaction *transaction in transactions) {
        switch(transaction.transactionState){
            case SKPaymentTransactionStatePurchasing: {
                // Your code ...
                break;
            }

            case SKPaymentTransactionStatePurchased: {
                // Your code ...
                [DTDAntiCheat verifyPaymentCompletion:^(DTDVerifyResponse * _Nonnull response) {
                    switch ([response receiptStatus]) {
                        case ReceiptStatusReceiptInternalError: {

                            break;
                        }
                        case ReceiptStatusReceiptValid: {

                            break;
                        }
                        case ReceiptStatusReceiptSandbox: {

                            break;
                        }
                        case ReceiptStatusReceiptServerError: {

                            break;
                        }
                        case ReceiptStatusReceiptNotValid: {

                            break;
                        }
                    }
                }];
                break;
            }

            case SKPaymentTransactionStateRestored: {
                // Your code ...
                break;
            }

            case SKPaymentTransactionStateFailed: {
                // Your code ...
                break;
            }

            case SKPaymentTransactionStateDeferred: {
                // Your code ...
                break;
            }
        }
    }
}

DTDVerifyResponse

The DTDVerifyResponse object returned while validating the transaction has two properties:

Property	Description
receiptStatus	Enum type DTDReceiptStatus that represents the result of the transaction validation.
verificationResult	Additional information from the validation server.

DTDReceiptStatus

The enum type returned as a result of validation can receive the following values:

Value	Description
receiptValid	The payment is valid, the transaction is genuine.
receiptNotValid	The payment is invalid, the transaction may be a duplicate or fraud.
receiptServerError	Server error when validating the payment.
receiptSandbox	Test payment.
receiptInternalError	Internal SDK error.

We recommend calling the Real Currency Payment method in all cases except when you receive receiptNotValid or receiptSandbox as a result of the validation.

Google Play (Kotlin)

When Google Play sends the transaction back to your onActivityResult, validate it by calling the following method: verifyPayment(receipt: String, signature: String, publicKey: String, completionHandler:(DTDVerifyResponse) -> Unit) immediately during the transaction processing, e.g.:

DTDAntiCheat.verifyPayment(
    receipt = "receipt", 
    signature = "signature", 
    publickKey = "publickKey"
) { dtdVerifyResponse ->
    val verificationResult = dtdVerifyResponse.verificationResult
    /* your code here */
    when (dtdVerifyResponse.receiptStatus) {
        DTDReceiptStatus.ReceiptValid -> { /* your code here */ }
        DTDReceiptStatus.ReceiptNotValid -> { /* your code here */ }
        DTDReceiptStatus.ReceiptServerError -> { /* your code here */ }
        DTDReceiptStatus.ReceiptInternalError -> { /* your code here */ }
    }
}

DTDVerifyResponse

The DTDVerifyResponse object returned while validating the transaction has two properties:

Property	Description
receiptStatus	Enum type DTDReceiptStatus that represents the result of the transaction validation.
verificationResult	Additional information from the validation server.

DTDReceiptStatus

The enum type returned as a result of validation can receive the following values:

Value	Description
receiptValid	The payment is valid, the transaction is genuine.
receiptNotValid	The payment is invalid, the transaction may be a duplicate or fraud.
receiptServerError	Server error when validating the payment.
receiptInternalError	Internal SDK error.

We recommend calling the Real Currency Payment method in all cases except when you receive receiptNotValid as a result of the validation.

Google Play (Java)

When Google Play sends the transaction back to your onActivityResult, validate it by calling the following method: verifyPayment(receipt: String, signature: String, publicKey: String, completionHandler:(DTDVerifyResponse) -> Unit) immediately during the transaction processing, e.g.:

DTDAntiCheat.INSTANCE.verifyPayment("receipt", "signature", "publickKey",
                dtdVerifyResponse -> {
                // your code
                    switch (dtdVerifyResponse.getReceiptStatus()) {
                        case ReceiptValid:
                            // your code
                            break;
                        case ReceiptNotValid:
                            // your code
                            break;
                        case ReceiptInternalError:
                            // your code
                            break;
                        case ReceiptServerError:
                            // your code
                            break;
                    }
                    return null;
                });

DTDVerifyResponse

The DTDVerifyResponse object returned while validating the transaction has two properties:

Property	Description
receiptStatus	Enum type DTDReceiptStatus that represents the result of the transaction validation.
verificationResult	Additional information from the validation server.

DTDReceiptStatus

The enum type returned as a result of validation can receive the following values:

Value	Description
receiptValid	The payment is valid, the transaction is genuine.
receiptNotValid	The payment is invalid, the transaction may be a duplicate or fraud.
receiptServerError	Server error when validating the payment.
receiptInternalError	Internal SDK error.

We recommend calling the Real Currency Payment method in all cases except when you receive receiptNotValid as a result of the validation.

Microsoft Store (UWP)

devtodev sends a request for transaction verification to the payment platform and then forwards the answer to the app. To validate the transaction you can use the Task<DTDReceiptStatus> VerifyPayment(string: receipt) method. As an argument pass the PurchaseResults.ReceiptXml property. More information about it here.

Example of verification:

var result = await DTDAntiCheat.VerifyPayment("receipt");
switch (result)
{
    case DTDReceiptStatus.Valid:
        break;
    case DTDReceiptStatus.Invalid:
        break;
    case DTDReceiptStatus.ServerError:
        break;
    case DTDReceiptStatus.InternalError:
        break;
    default:
        throw new ArgumentOutOfRangeException();
}

DTDVerifyResponse

The DTDVerifyResponse object returned while validating the transaction has two properties:

Property	Description
ReceiptStatus	Enum type DTDReceiptStatus that represents the result of the transaction validation.
VerificationResult	Additional information from the validation server.

DTDReceiptStatus

The enum type returned as a result of validation can receive the following values:

Value	Description
Valid = 0L	The payment is valid, the transaction went through successfully
Invalid = 1L	The payment is invalid, the transaction may be a duplicate or fraud
ServerError = 2L	Server error when validating the payment
InternalError = 4L	Internal SDK error

We recommend calling the Real Currency Payment method in all cases except when you receive Invalid as a result of the validation.

Unity (3 stores )

Google Play

If you use Unity IAP for payment validation, call the following method: void VerifyPayment(string publicKey, string receipt, Action completionHandler)

Example:

public PurchaseProcessingResult ProcessPurchase (PurchaseEventArgs e)
{
    DTDAntiCheat.VerifyPayment(yourPublicKey, e.purchasedProduct.receipt, result =>
    {
        if (result.ReceiptStatus == DTDReceiptVerificationStatus.ReceiptValid ||
            result.ReceiptStatus == DTDReceiptVerificationStatus.ReceiptInternalError || 
            result.ReceiptStatus == DTDReceiptVerificationStatus.ReceiptServerError)
        {
            // Code for valid result.
        }
        else
        {
            // Code for invalid result.
        }
    });
}

To validate data received from Google Play, use void VerifyPayment(string publicKey, string receipt, string signature,Action<DTDVerifyResponse> completionHandler) when handling the transaction.

public void MyNativeCallback (string publicKey, string receipt, string signature)
{
    DTDAntiCheat.VerifyPayment(publicKey, receipt, signature, result =>
    {
        if (result.ReceiptStatus == DTDReceiptVerificationStatus.ReceiptValid ||
            result.ReceiptStatus == DTDReceiptVerificationStatus.ReceiptInternalError || 
            result.ReceiptStatus == DTDReceiptVerificationStatus.ReceiptServerError)
        {
            // Code for valid result.
        }
        else
        {
            // Code for invalid result.
        }
    });
}

Here's how to find your app's public key for licensing (for Google Play platform only, for other platforms the publicKey is not used):

1. Go to the Google Play Console and sign in. Make sure that you sign in to the account from which the app you are licensing is published (or will be published).

2. In the app details page, locate the Services & APIs link and click it.

3. In the Services & APIs page, locate the Licensing & In-App Billing section. Your public key for licensing is given in the Your License Key For This Application field.

App Store

If you use Unity IAP for payment validation, call the following method: void VerifyPayment(string receipt, Action completionHandler)

public PurchaseProcessingResult ProcessPurchase (PurchaseEventArgs e)
{
    DTDAntiCheat.VerifyPayment(e.purchasedProduct.receipt, result =>
    {
        if (result.ReceiptStatus == DTDReceiptVerificationStatus.ReceiptValid ||
            result.ReceiptStatus == DTDReceiptVerificationStatus.ReceiptInternalError || 
            result.ReceiptStatus == DTDReceiptVerificationStatus.ReceiptServerError)
        {
            // Code for valid result.
        }
        else
        {
            // Code for invalid result.
        }
    });
}

Windows Store (UWP)

If you use Unity IAP for payment validation, call the following method: void VerifyPayment(string receipt, Action completionHandler)

public PurchaseProcessingResult ProcessPurchase (PurchaseEventArgs e)
{
    DTDAntiCheat.VerifyPayment(e.purchasedProduct.receipt, result =>
    {
        if (result.ReceiptStatus == DTDReceiptVerificationStatus.ReceiptValid ||
            result.ReceiptStatus == DTDReceiptVerificationStatus.ReceiptInternalError || 
            result.ReceiptStatus == DTDReceiptVerificationStatus.ReceiptServerError)
        {
            // Code for valid result.
        }
        else
        {
            // Code for invalid result.
        }
    });
}

N.B. You can pass a native XML recipe to the receipt argument.

DTDVerifyResponse

The DTDVerifyResponse object returned while validating the transaction has two properties:

Property	Description
receiptStatus	Enum type DTDReceiptStatus that represents the result of the transaction validation.
verificationResult	Additional information from the validation server.

DTDReceiptStatus

The enum type returned as a result of validation can receive the following values:

Value	Description
receiptValid	The payment is valid, the transaction is genuine.
receiptNotValid	The payment is invalid, the transaction may be a duplicate or fraud.
receiptServerError	Server error when validating the payment.
receiptSandbox	Test payment.
receiptInternalError	Internal SDK error.

We recommend calling the Real Currency Payment method in all cases except when you receive receiptNotValid or receiptSandbox as a result of the validation.