QR Generation 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://sandbox.payu.in/api/v1/invoice/seamless' \
--header 'date: Wed, 01 Jun 2022 13:35:16 GMT' \
--header 'digest: AgeDjE/vWQI8GHZPNwJHH4ugppwl0TEaTLe+aIwTU2Q=' \
--header 'authorization: hmac username="smmsplus", algorithm="hmac-sha256", headers="date digest", signature="BumCt753bJvr1GaJZmfuhu8XIDQNSBirj07dVQuaPJI="' \
--header 'Content-Type: application/json' \
--data-raw '{
"txnid": "sl-0199104",
"amount": "120",
"productinfo": "iphone",
"firstname": "Ayush",
"lastname": "Agarwal",
"email": "[email protected]",
"phone": "8087667676",
"address1": "sec-24",
"address2": "Big Road",
"city": "Gurgaon",
"state": "Haryana",
"country": "India",
"zipcode": 123456,
"udf1": "udf1value",
"udf2": "udf2value",
"udf3": "udf3value",
"udf4": "udf4value",
"udf5": "udf5value",
"enforce_paymethod": "UPI",
"expiryTime": "120",
"outputType": "base64",
"displayFields": {
"DF1": "DF1Value",
"DF2": "DF2Value",
"DF3": "DF3Value",
"DF4": "DF4Value"
},
"send_sms": 1
}'	

{
    "invoiceUrl": “https://reliance-testwebfront.payu.in/iv/00twqu”, 
"qrString": "data:image/png;base64,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"
}

{
"invoiceUrl": " https://reliance-testwebfront.payu.in/iv/00twqu"
}

{
    "status": “0”, “code”:400,
    "message": "txnid is empty"
}

{
    "status": “0”, “code”:400,
    "message": "Amount is less than 1"
}