# QuickBuy Callback
## Overview
The body of this request contains details about the requested exchange and the captured payment once the exchange has been agreed.
## Completed fiat payment callback
The body of this request contains details about the requested exchange and the captured payment once the exchange has been agreed.
Key details:
* `transactionReference` is our reference for the transaction, for use in correspondence.
* `status` is currently always `SUCCESS` as this callback currently only occurs for captured payments. In future other status codes may be added.
* The `requestDetails` object contains:
* client signature and user reference used to initiate the widget,
* user selected asset, currency, and payment amount,
* the estimate displayed to the user of the amount of crypto asset to purchase, and
* other details about the widget instantiation like the timestamp and IP address.
* The `transactionDetails` object contains:
* payment card details;
* payment capture date;
* confirmation of the amount charged to the user's card;
* confirmation of the fee charged - the amount used to buy the crypto will be the charged amount less this fee;
* the amount of the crypto asset to be purchased (note that there are several transactions to make before this reaches the nominated external wallet, and some fees may be incurred);
* an estimated value in the selected fiat currency of this crypto amount; and
* other details such as the card payment processor.
* The content type of the body is `application/json`.
### Callback Example
{
"TransactionReference": "QBWE1001",
"Status": "SUCCESS",
"RequestDetails": {
"UserReference": "TestWidgetUser1",
"ClientSignature": "lafsao7y4v5q847yrjerocq32yroaerq398",
"CryptoAssetCode": "USDC",
"FiatCurrencyCode": "USD",
"FiatCurrencyAmount": 50,
"CryptoAssetAmount": 49.95,
"RequestDate": "2022-02-18T14:30:59.52",
"RequestIp": "51.141.9.231"
},
"TransactionDetails": {
"StatementDescriptor": null,
"PaymentProcessor": "Processor 1",
"CryptoAssetGrossAmount": 47,
"CryptoAssetEstimatedFiatValue": 47.5,
"FiatCurrencyChargedAmount": 50,
"FiatCurrencyFeeAmount": 2.5,
"PaymentCaptureDate": "2022-02-18T14:31:59.577",
"PaymentCardLast4Digits": "1111"
}
}
[**We will include a signing header with this request (see below).**](#callback-signing)
***
## Completed Cryptocurrency deposit callback
The body of this request contains details about transaction which deposits the cryptocurrency into the customers wallet.
Key details:
* `transactionReference` is our reference for the transaction, for use in correspondence.
* `status` is currently always `SUCCESS` as this callback currently only occurs for captured payments. In future other status codes may be added.
* The `requestDetails` object contains:
* client signature and user reference used to initiate the widget,
* user selected asset, currency, and payment amount,
* the estimate displayed to the user of the amount of crypto asset to purchase, and
* other details about the widget instantiation like the timestamp and IP address.
* The `transactionDetails` object contains:
* payment card details;
* payment capture date;
* confirmation of the amount charged to the user's card;
* confirmation of the fee charged - the amount used to buy the crypto will be the
* charged amount less this fee;
* the amount of the crypto asset to be purchased (note that there are several transactions to make before this reaches the nominated external wallet, and some fees may be incurred);
* an estimated value in the selected fiat currency of this crypto amount;
* **the transaction hash**; and
* other details such as the card payment processor.
* The content type of the body is `application/json`.
### Completed cryptocurrency deposit callback body
{
"TransactionReference": "QBWE1001",
"Status": "SUCCESS",
"RequestDetails": {
"UserReference": "TestWidgetUser1",
"ClientSignature": "lafsao7y4v5q847yrjerocq32yroaerq398",
"CryptoAssetCode": "USDC",
"FiatCurrencyCode": "USD",
"FiatCurrencyAmount": 50,
"CryptoAssetAmount": 49.95,
"RequestDate": "2022-02-18T14:30:59.52",
"RequestIp": "51.141.9.231"
},
"TransactionDetails": {
"StatementDescriptor": null,
"PaymentProcessor": "Processor 1",
"CryptoAssetGrossAmount": 47,
"CryptoAssetEstimatedFiatValue": 47.5,
"FiatCurrencyChargedAmount": 50,
"FiatCurrencyFeeAmount": 2.5,
"PaymentCaptureDate": "2022-02-18T14:31:59.577",
"PaymentCardLast4Digits": "1111",
"TransactionHash": "0x9ec48ce0653cc7b2bcaa463a92b3191ddee5275d897854f2d210d2b298828d00"
}
}
[**We will include a signing header with this request (see below).**](#callback-signing)
***
## Callback Signing
In order for you to authenticate a call to your payment capture webhook we will sign it using the shared secret provided to you. To generate the signing header we:
* Append the shared secret (in UTF8 encoding) to the bytes of the request body.
* Perform a SHA256 hash on the result
* Provide the hash value in the QuickBuy-Signature header for the callback (encoded as a base64 string).
Note: This only applies to the payment capture callback, we currently do not sign the initial authentication callback.
### [See the code examples for checking the callback signature.](/quickbuy/validating-the-webhook-signature.md)
---
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