Provision Alt ID API

import com.google.gson.Gson;
import com.google.gson.JsonObject;
import org.apache.commons.codec.binary.Base64;
import org.joda.time.DateTime;
import org.joda.time.format.DateTimeFormat;

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import java.security.InvalidKeyException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class HmacAuth {

    public static String getSha256(String input) {
        try {
            MessageDigest md = MessageDigest.getInstance("SHA-256");
            byte[] digest = md.digest(input.getBytes());
            return Base64.encodeBase64String(digest);
        } catch (NoSuchAlgorithmException ignored) {}
        return null;
    }

    public static JsonObject getRequestBody(){
        JsonObject requestJson = new JsonObject();
        requestJson.addProperty("firstname","John");
        requestJson.addProperty("lastname","Doe");
        return requestJson;
    }

    public static void main(String[] args) throws NoSuchAlgorithmException, InvalidKeyException {
        String key = "smsplus";
        String secret = "admin";
        Gson gson = new Gson();
        String date = DateTimeFormat.forPattern("EEE, dd MMM yyyy HH:mm:ss 'GMT'").withZoneUTC().print(new DateTime());
        System.out.println(date);
        JsonObject requestJson = getRequestBody();
        String digest = getSha256(gson.toJson(requestJson));
        System.out.println(digest);
        String signingString = new StringBuilder()
            .append("date: " + date)
            .append("\ndigest: " + digest).toString();
        Mac sha256_HMAC = Mac.getInstance("HmacSHA256");
        SecretKeySpec secret_key = new SecretKeySpec(secret.getBytes(), "HmacSHA256");
        sha256_HMAC.init(secret_key);
        String signature = Base64.encodeBase64String(sha256_HMAC.doFinal(signingString.getBytes()));
        String authorization = new StringBuilder()
            .append("hmac username=\"")
            .append(key)
            .append("\", algorithm=\"hmac-sha256\", headers=\"date digest\", signature=\"")
            .append(signature)
            .append("\"").toString();
        System.out.println(authorization);
    }
}

curl --location --request POST 'https://apitest.payu.in/card/altid' \
--header 'Content-Type: application/json' \
--header 'date: Fri, 12 Jan 2024 10:13:08 GMT' \
--header 'digest: n6XDOH1fAUrD+WC47SFsa+mNxmm1+yTrUAupmxbYMoc=' \
--header 'authorization: hmac username="DGy1hY", algorithm="hmac-sha256", headers="date digest", signature="FBp5QsOIxBzxyDnRXPCt76htkdm5ijc4nm/Hvyvaw/s="' \
--data-raw '{
    "clientReferenceId": null,
    "cardNumber": "5299920970259709",
    "nameOnCard": "Jagadesh Reddy",
    "cardType": "MAST",
    "expiryMonth": "06",
    "expiryYear": "2024",
    "cvv": "000",
    "mail": "[email protected]",
    "amount": "100",
    "authenticationCode": null
}'

{
    "statusCode": "EA01",
    "status": 1,
    "clientReferenceId": "339c6c458ac3161da90839",
    "tokenReferenceId": "018b90aa-b9c5-41c0-8528-71dd22b6b65e",
    "cryptogram": "IjDso7oA5xFBdiOd/m035meW5UpImrSRAXWMe7406m0=",
    "altInfo": {
        "altIdToken": "3612143521818338",
        "expiryMonth": "09",
        "expiryYear": "2026",
        "last4": "6622"
    },
    "msg": "AltID created successful",
    "par": "799F3ED865F5965CC760A32682BA8A80F19E99ECB3F7F03574C14F5B6C3EB2C1"
}