DeviceConnect: REST API

FinBox DeviceConnect REST API enables "server to server data" fetching of customers' Android device data. The customer's data can be fetched using the CUSTOMER_ID. API accepts JSON-encoded request bodies, returns JSON-encoded responses.

NOTE

Following will be shared by FinBox team at the time of integration:

• SERVER_API_KEY
• SERVER_HASH
• DC_PREDICTORS_VERSION

Authentication

FinBox provides a valid and signed certificate for all API methods and endpoints. To access the API methods requester must ensure that their connection library supports HTTPS.

Authentication for the APIs are based on SERVER_API_KEY provided by the FinBox. Server to server communication can commence when IP of requester are whitelisted on the FinBox servers. This can be easily done upon request.

API Integration Workflow

Insights API

Once FinBox DeviceConnect SDK is initialized, data from the device is sent to the FinBox processing engine against an anonymous CUSTOMER_ID which will be the primary key from retrieving any information from the server.

Clients need to call the Insights API with CUSTOMER_ID to get the predictors for a given customer. A sample workflow is shown in section below. In case Insights API returns with status "in_progress" (meaning data is currently being processed), the client should poll the Insights API with a delay of at least 10 seconds

Workflow

1. Call FinBox Insights API
2. In case the response status is "in_progress", retry after 10 seconds
3. In case the response status is "complete", receive data as per format mentioned in this section.

Insights API Endpoints

Base URL

For all the endpoints, the base URL for different environments are as follows:

Environment	Base URL
Production	https://insights.finbox.in/v2/
Development	https://insights.finbox.in/staging/

Insights	Endpoint	Request Type	Description
General Predictors	/risk/predictors	POST	General features extracted from customer's data

Predictors

Other than general predictors, there are also more predictor endpoints which will be shared based on the requirement by the FinBox team.

Insights API Request

Request Header and Body

For all the Insights API request structure is the same, all requests must have x-api-key field in header having the value as the SERVER_API_KEY shared by FinBox team. The following keys must be passed in every request body as keys to a JSON document:

Request Body

Key	Type	Description
customer_id	String	CUSTOMER_ID for which feature vector is required
version	Integer	Version of the feature set shared by FinBox team as DC_PREDICTORS_VERSION
salt	String	A salt which is computed basis logic mentioned in the section below

IMPORTANT

Please note that this CUSTOMER_ID is the same used as the unique identifier used in Android SDK while syncing the data.

Calculating salt

Salt is calculated as follows:

1. A = Create MD5 hash of CUSTOMER_ID
2. B = Concatenate string of A and SERVER_HASH shared by FinBox.
3. C = Create an SHA-256 hash of B
4. Salt = base64 encoded version of C

Sample code for salt generation in different languages:

• Java
• Python
• Go

import java.security.*;
import java.util.*;
import java.io.UnsupportedEncodingException;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.math.BigInteger;
​
​
public class SaltGeneration {
    private static final int HEX_255 = 0xFF;
    private static final String UNICODE_TRANSFORMATIONAL_FORMAT_8_BIT = "UTF-8";
    private static String CUSTOMER_ID = "<CUSTOMER_ID>";
    private static String SERVER_HASH = "<SERVER_HASH>";
    
    private static String getSaltForBody() {
        String hashedOutput = getMd5Hash(CUSTOMER_ID);
        String concatString = hashedOutput + SERVER_HASH;
        String shaOutput = get256Encoded(concatString);
        return shaOutput;
    }
​
​
    private static String getMd5Hash(final String s) {
        try {
            // Create MD5 Hash
            MessageDigest digest = MessageDigest.getInstance("MD5");
            digest.update(s.getBytes(Charset.forName(UNICODE_TRANSFORMATIONAL_FORMAT_8_BIT)));
            byte[] messageDigest = digest.digest();
    
            // Create Hex String
            StringBuilder hexString = new StringBuilder();
            for (byte mDigest : messageDigest) {
                StringBuilder h = new StringBuilder(Integer.toHexString(HEX_255 & mDigest));
                while (h.length() < 2) {
                    h.insert(0, "0");
                }
                hexString.append(h);
            }
            return hexString.toString().toUpperCase();
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
        return null;
    }
​
    /**
     * Method converts the string into SHA 256 and returns it
     *
     * @param s String to be 256 encoded
     * @return Converted 256 hash
     */
    private static String get256Encoded(final String text) {
        try {
            MessageDigest digest = MessageDigest.getInstance("SHA-256");
            byte[] hash = digest.digest(text.getBytes(StandardCharsets.UTF_8));
            return Base64.getEncoder().encodeToString(hash);
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
        return null;
    }
}

import hashlib, base64

def create_salt(customer_id, server_hash):
    """
    Takes customer_id (unique identifier of customer)
    and server_hash (shared by FinBox) as input
    and returns salt in response
    """
    customer_hash = hashlib.md5(customer_id.encode('utf-8')).hexdigest().upper()
    intermediate_hash = customer_hash + server_hash
    salt_encoded = hashlib.sha256(intermediate_hash.encode('utf-8')).digest()
    salt = base64.b64encode(salt_encoded).decode()
    return salt

import (
	"crypto/md5"
	"crypto/sha256"
	"fmt"
	"encoding/base64"
	"encoding/hex"
	"strings"
)
func GetSaltForCustomer(customerId string, serverHash string) string {
    hasher := md5.New()
	hasher.Write([]byte(customerId))
	hexHasher := hex.EncodeToString(hasher.Sum(nil))
	data := strings.ToUpper(hexHasher)+ serverHash
	newSha256 := sha256.New()
	newSha256.Write([]byte(data))
    finalData := base64.StdEncoding.EncodeToString(newSha256.Sum(nil))
	return finalData
}

Sample Request

Headers

Content-Type: application/json
x-api-key: XXXX-XXXX-XXXX

Request Body

{
    "customer_id": "1234ABCD4567",
    "version": 1,
    "salt": "5vVMNofMy5kQXx647sBdYBoMolMb1GGBSYLkzwaa9v8="
}

Insights API Response

API will give a JSON Response with the following keys:

Response Keys

Key	Description	Type	Nullable
customer_id	CUSTOMER_ID for which data was requested	STRING [260]	Yes
request_id	A unique string for each request	STRING [32]	Yes
status	Status of the operation.	STRING [20]	No
message	Description of status	STRING [200]	No
date_requested	Timestamp of processing request	STRING with YYYY-MM-DDThh:mm:ss:mil format	Yes
date_processed	Timestamp of processing completion	STRING with YYYY-MM-DDThh:mm:ss:mil format	Yes
data	An array of objects, each object representing the predictors, having keys name indicating the predictor name and value indicating the values	JSON	Yes

data key

The list of predictors in the data key will be different based on the result API endpoint, feature set version and requester. This list will hence be shared separately by the FinBox team during the integration.

NOTE

Some of the keys in response may be missing based on the availability of data and HTTP Status code. Please refer to examples for each of the cases listed here.

status values

Depending on the availability of data, there can be different cases with different status values as follows:

Case	status value	HTTP Status Code	Description / Action
Calculation in progress	"in_progress"	202	The request input is correct and processing has started. Please retry in 10 seconds
Calculation complete and data is available	"complete"	200	The request input is correct and processing has completed. Response contains the predictors
Calculation complete and data is unavailable	"no_data"	200	The request input is correct and processing has completed but response contains no predictors because of lack of data from user's device
Invalid customer ID	"not_found"	200	User does not exist in FinBox system
Bad request	"error"	400	The request input is incorrect / malformed. More details available in message key
Unauthorized	"error"	403	This happens in case SERVER_API_KEY is incorrect or IP address in not whitelisted
Internal Server Error	"error"	5xx	The request processing failed because of some internal error. In this case, please retry twice with an exponential backoff i.e. retry after 2 seconds, then retry after 5 seconds. If the issue persists, please contact support
Rate Limit Exceeded	"error"	429	This happens in case the maximum allowed rate limit on API exceeds. In this case, please retry twice with an exponential backoff i.e. retry after 2 seconds, then retry after 5 seconds. Contact FinBox to know your rate limits.

IMPORTANT

In case your are running a daily CRON that fetches data using insights API, ensure you are not breaching the rate limit. Please contact FinBox to know your rate limits.

Case 1 - Calculation in Progress

HTTP Status Code: 202

Sample Response Body:

{
    "customer_id": "A145BC6312B50CA2B58233288F81C02114A6A74E9A62482169F9F",
    "request_id": "abcd-def-dfdf-xcds1",
    "date_requested": "2019-01-03T06:37:44:003",
    "status": "in_progress",
    "message": "Featurization in Progress, please try again in 10 Seconds"
}

Case 2 - Calculation complete and data is available

HTTP Status Code: 200

Sample Response Body:

{
    "customer_id": "A145BC6312B50CA2B58233288F81C02114A6A74E9A62482169F9F",
    "request_id": "abcd-def-dfdf-jjj1",
    "date_requested": "2019-01-03T06:37:44:003",
    "date_processed": "2018-12-12T01:01:57:221",
    "status": "complete",
    "message": "data processed successfully",
    "data": [] // will hold the predictor objects
}

Case 3 - Calculation complete and data is unavailable

HTTP Status Code: 200

Sample Response Body:

{
    "customer_id": "A145BC6312B50CA2B58233288F81C02114A6A74E9A62482169F9F",
    "request_id": "abcd-def-dfdf-000l",
    "date_requested": "2019-01-03T06:37:44:003",
    "date_processed": "2018-12-12T01:01:57:221",
    "status": "no_data",
    "message": "No data available for user",
    "data": null
}

Case 4 - Invalid Customer ID

HTTP Status Code: 200

Sample Response Body:

{
    "customer_id": "A145BC6312B50CA2B58233288F81C02114A6A74E9A62482160F9F",
    "request_id": "abcd-def-dfdf-ddd1",
    "date_requested": "2019-01-03T06:37:44:003",
    "date_processed":null,
    "status": "not_found",
    "message": "User not found",
    "data": null
}

Case 5 - Bad Request

HTTP Status Code: 400

Sample Response Body:

{
    "customer_id": "A145BC6312B50CA2B58233288F81C02114A6A74E9A62482160F9F",
    "request_id": "abcd-def-dfdf-ddd1",
    "date_requested": "2019-01-03T06:37:44:003",
    "status": "error",
    "message":"Missing Key version"
}

Case 6 - Unauthorized

HTTP Status Code: 403

Sample Response Body:

{
    "status": "error",
    "message": "Incorrect API Key"
}

Case 7 - Internal Server Error

HTTP Status Code: 5xx

Sample Response Body:

{
    "status": "error",
    "message": "Internal Server Error. Please retry. If issue persists, please contact support"
}

Case 8 - Rate Limit Exceeded

HTTP Status Code: 429

Sample Response Body:

{
    "status": "error",
    "message": "Rate limit exceeded"
}

Predictors Webhook Integration

FinBox fires a webhook when a user's results are updated. Upon receipt of the webhook, you can query the insights API to fetch these results.

The webhook payload has the following keys:

• service: It indicates the service whose results have been updated. Currently, It will be set to PREDICTORS.
• customer_id: customer_id for which result was updated.
• salt: A salt is used to authenticate webhook. It is computed basis logic mentioned in the section below
• request_id: A unique string corresponding to each each request

IMPORTANT

You have to register your webhook address with FinBox. Please get in touch with us for the same.

{
    "service": "PREDICTORS",
    "customer_id": "89561ea2190946a9",
    "salt": "/+Y459HYwFtWB2656bE5eTvB4NmTSoTmoAyt9SAtwek=",
    "request_id": "aad12-dabmd-ddb-1123d"
}

Calculating Webhook Salt

Salt is calculated as follows:

1. A = Create MD5 hash of CUSTOMER_ID
2. B = Concatenate string of A and WEBHOOK_SECRET shared by FinBox.
3. C = Create an SHA-256 hash of B
4. Salt = base64 encoded version of C

Sample code for salt generation in different languages:

• Java
• Python
• Go

import java.security.*;
import java.util.*;
import java.io.UnsupportedEncodingException;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.math.BigInteger;
​
​
public class SaltGeneration {
    private static final int HEX_255 = 0xFF;
    private static final String UNICODE_TRANSFORMATIONAL_FORMAT_8_BIT = "UTF-8";
    private static String CUSTOMER_ID = "<CUSTOMER_ID>";
    private static String WEBHOOK_SECRET = "<WEBHOOK_SECRET>";
    
    private static String getSaltForBody() {
        String hashedOutput = getMd5Hash(CUSTOMER_ID);
        String concatString = hashedOutput + WEBHOOK_SECRET;
        String shaOutput = get256Encoded(concatString);
        return shaOutput;
    }
​
​
    private static String getMd5Hash(final String s) {
        try {
            // Create MD5 Hash
            MessageDigest digest = MessageDigest.getInstance("MD5");
            digest.update(s.getBytes(Charset.forName(UNICODE_TRANSFORMATIONAL_FORMAT_8_BIT)));
            byte[] messageDigest = digest.digest();
    
            // Create Hex String
            StringBuilder hexString = new StringBuilder();
            for (byte mDigest : messageDigest) {
                StringBuilder h = new StringBuilder(Integer.toHexString(HEX_255 & mDigest));
                while (h.length() < 2) {
                    h.insert(0, "0");
                }
                hexString.append(h);
            }
            return hexString.toString().toUpperCase();
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
        return null;
    }
​
    /**
     * Method converts the string into SHA 256 and returns it
     *
     * @param s String to be 256 encoded
     * @return Converted 256 hash
     */
    private static String get256Encoded(final String text) {
        try {
            MessageDigest digest = MessageDigest.getInstance("SHA-256");
            byte[] hash = digest.digest(text.getBytes(StandardCharsets.UTF_8));
            return Base64.getEncoder().encodeToString(hash);
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
        return null;
    }
}

import hashlib, base64

def create_salt(customer_id, webhook_secret):
    """
    Takes customer_id (unique identifier of customer)
    and webhook_secret (shared with FinBox) as input
    and returns salt in response
    """
    customer_hash = hashlib.md5(customer_id.encode('utf-8')).hexdigest().upper()
    intermediate_hash = customer_hash + webhook_secret
    salt_encoded = hashlib.sha256(intermediate_hash.encode('utf-8')).digest()
    salt = base64.b64encode(salt_encoded).decode()
    return salt

import (
	"crypto/md5"
	"crypto/sha256"
	"fmt"
	"encoding/base64"
	"encoding/hex"
	"strings"
)
func GetSaltForCustomer(customerId string, webhookSecret string) string {
    hasher := md5.New()
	hasher.Write([]byte(customerId))
	hexHasher := hex.EncodeToString(hasher.Sum(nil))
	data := strings.ToUpper(hexHasher)+ webhookSecret
	newSha256 := sha256.New()
	newSha256.Write([]byte(data))
    finalData := base64.StdEncoding.EncodeToString(newSha256.Sum(nil))
	return finalData
}

Querying by webhook

Once you receive a webhook, you can make a POST request of the insights API using the param source = webhook and request_id = {request_id}. This will return the updated data to you instantly.

https://insights.finbox.in/v2/risk/predictors?source=webhook&request_id={request_id}

IMPORTANT

• You must only use the source param once you have received the webhook.
• Param request_id must be the same as the request_id received in the response payload of the webhook.
• Including this param bypasses the calculation of results and returns already existing result.