After some events that was not initiated by the client there can be a callback with the data about the event.

Callback is a request from our servers to client's server. This way data about event is passed to callback_uri, defined in project configuration in Paysera system or provided when creating a transaction.

Possible events are these:

Callback structure

Our servers make POST request to callback_uri in your server. Parameters are encoded in application/x-www-form-urlencoded format which is automatically parsed in the most of programming languages.

Callback parameters

Event parameter structure

Verifying sign

Sign is calculated using this formula:

sign = base64_encode(RSA(event, d, n))

RSA is public key algorithm, using sha256 encoding.

Most of cryptographic libraries give a way to check if some data was encrypted with RSA algorithm by giving a public key. Reverse action is practically not possible - private key is needed for that. Checking algorithm:
ok = verify, that base64_decode(sign) is the result when event is signed with publicKey

For example, in PHP language sign can be checked with this code:

// get $webToPayPublicKey
$ok = openssl_verify($_POST['event'], base64_decode($_POST['sign']), $webToPayPublicKey, 'sha256');
if ($ok) {
    $event = json_decode($_POST['event']);
    // ...
}

Public key used in sign verifying is provided by Paysera system and is publicly accessible by this URI:

https://wallet.paysera.com/publickey

Response status codes

Server must return status code 200 (or any other 2xx) if the callback has been successfully processed and any other status code if not - in that case callback will be repeated after some time. Server should not provide redirect status codes (3xx).

Keep in mind, that transaction is canceled or confirmed no matter what callback status code is - there might even not be any callback.

Examples

Transaction rejected callback example

POST /your_provided_callback_uri HTTP/1.1
Host: example.com

event=%7B%22type%22%3A%22rejected%22%2C%22object%22%3A%22transaction%22%2C%22data%22%3A%7B%22transaction_key%22%3A%22pDAlAZ3z%22%2C%22created_at%22%3A1355314332%2C%22status%22%3A%22rejected%22%2C%22type%22%3A%22page%22%2C%22wallet%22%3A14471%2C%22project_id%22%3A2248%2C%22payments%22%3A%5B%7B%22id%22%3A2988%2C%22transaction_key%22%3A%22pDAlAZ3z%22%2C%22created_at%22%3A1355314332%2C%22status%22%3A%22canceled%22%2C%22price%22%3A1299%2C%22currency%22%3A%22EUR%22%2C%22price_decimal%22%3A%2212.99%22%2C%22wallet%22%3A14471%2C%22description%22%3A%22Payment+for+order+No.+1234%22%2C%22parameters%22%3A%7B%22orderid%22%3A1234%7D%2C%22transfer_id%22%3A578842%7D%5D%7D%7D&sign=f75rkX5qrvS3i9%2frQraUKPZOIW4MOXuFyy0yVMYc2SHoRFABko23oDBeCagGI9V9RUmeE6s5PMHLZ%2fYQJtePAkEA%2f0DCozbYbz%2bxlGwhg7kHvH0LqCB6sITxfzMaFQbT8EGmloj4wIkgvEImgBTyJ3xIZulcDwFpT9qApIKmcCm3Q%3d%3d

event contents (urldecoded and formatted):

{
    "type": "rejected",
    "object": "transaction",
    "data": {
        "transaction_key": "pDAlAZ3z",
        "created_at": 1355314332,
        "status": "rejected",
        "type": "page",
        "wallet": 14471,
        "project_id": 2248,
        "payments": [
            {
                "id": 2988,
                "transaction_key": "pDAlAZ3z",
                "created_at": 1355314332,
                "status": "canceled",
                "price": 1299,
                "currency": "EUR",
                "wallet": 14471,
                "price_decimal": "12.99",
                "description": "Payment for order No. 1234",
                "parameters": {
                    "orderid": 1234
                },
                "transfer_id": 578842
            }
        ]
    }
}

Transaction reserved callback example

POST /your_provided_callback_uri HTTP/1.1
Host: example.com

event=%7B%22type%22%3A%22reserved%22%2C%22object%22%3A%22transaction%22%2C%22data%22%3A%7B%22transaction_key%22%3A%22pDAlAZ3z%22%2C%22created_at%22%3A1355314332%2C%22status%22%3A%22reserved%22%2C%22type%22%3A%22page%22%2C%22wallet%22%3A14471%2C%22project_id%22%3A2248%2C%22payments%22%3A%5B%7B%22id%22%3A2988%2C%22transaction_key%22%3A%22pDAlAZ3z%22%2C%22created_at%22%3A1355314332%2C%22status%22%3A%22reserved%22%2C%22price%22%3A1299%2C%22currency%22%3A%22EUR%22%2C%22price_decimal%22%3A%2212.99%22%2C%22wallet%22%3A14471%2C%22freeze%22%3A%7B%22until%22%3A1357992732%7D%2C%22description%22%3A%22Payment+for+order+No.+1234%22%2C%22parameters%22%3A%7B%22orderid%22%3A1234%7D%2C%22transfer_id%22%3A578842%7D%5D%7D%7D&sign=f75rkX5qrvS3i9%2frQraUKPZOIW4MOXuFyy0yVMYc2SHoRFABko23oDBeCagGI9V9RUmeE6s5PMHLZ%2fYQJtePAkEA%2f0DCozbYbz%2bxlGwhg7kHvH0LqCB6sITxfzMaFQbT8EGmloj4wIkgvEImgBTyJ3xIZulcDwFpT9qApIKmcCm3Q%3d%3d

event contents (urldecoded and formatted):

{
    "type": "reserved",
    "object": "transaction",
    "data": {
        "transaction_key": "pDAlAZ3z",
        "created_at": 1355314332,
        "status": "reserved",
        "type": "page",
        "wallet": 14471,
        "project_id": 2248,
        "payments": [
            {
                "id": 2988,
                "transaction_key": "pDAlAZ3z",
                "created_at": 1355314332,
                "status": "reserved",
                "price": 1299,
                "currency": "EUR",
                "price_decimal": "12.99",
                "wallet": 14471,
                "freeze": {
                    "until": 1357992732
                },
                "description": "Payment for order No. 1234",
                "parameters": {
                    "orderid": 1234
                },
                "transfer_id": 578842
            }
        ]
    }
}