var client = new RestClient("https://sandbox.dapp.mx/v2/cashin/reference");
client.Timeout = 60;
var request = new RestRequest(Method.POST);
client.UserAgent = "MyApp 1.0";
request.AddHeader("Authorization", "Basic OnlvdXItYXBpLWtleQ==");
request.AddHeader("Content-Type", "application/json");
var body = @"{" + "\n" +
@"    ""amount"":100.00" + "\n" +
@"}";
request.AddParameter("application/json", body,  ParameterType.RequestBody);
IRestResponse response = client.Execute(request);

OkHttpClient client = new OkHttpClient().newBuilder()
  .build();
MediaType mediaType = MediaType.parse("application/json");
RequestBody body = RequestBody.create(mediaType, "{\n    \"amount\":100.00\n}");
Request request = new Request.Builder()
  .url("https://sandbox.dapp.mx/v2/cashin/reference")
  .method("POST", body)
  .addHeader("User-Agent", "MyApp 1.0")
  .addHeader("Authorization", "Basic OnlvdXItYXBpLWtleQ==")
  .addHeader("Content-Type", "application/json")
  .build();
Response response = client.newCall(request).execute();

import requests
import json

url = "https://sandbox.dapp.mx/v2/cashin/reference"

payload = json.dumps({
  "amount": 100
})
headers = {
  'User-Agent': 'MyApp 1.0',
  'Authorization': 'Basic OnlvdXItYXBpLWtleQ==',
  'Content-Type': 'application/json'
}

response = requests.request("POST", url, headers=headers, data=payload)

import java.io.IOException;
import java.math.BigInteger;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.security.InvalidKeyException;
import java.security.KeyFactory;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.Signature;
import java.security.SignatureException;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.X509EncodedKeySpec;
import java.util.Base64;
import java.util.List;

import javax.crypto.BadPaddingException;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;

public class dapp {

    public static String encryptThisString(String input)
    {
        try {
            // getInstance() method is called with algorithm SHA-512
            MessageDigest md = MessageDigest.getInstance("SHA-512");
            // digest() method is called
            // to calculate message digest of the input string
            // returned as array of byte
            byte[] messageDigest = md.digest(input.getBytes());
            // Convert byte array into signum representation
            BigInteger no = new BigInteger(1, messageDigest);
            // Convert message digest into hex value
            String hashtext = no.toString(16);
            // Add preceding 0s to make it 32 bit
            while (hashtext.length() < 32) {
                hashtext = "0" + hashtext;
            }
            // return the HashText
            return hashtext;
        }
        // For specifying wrong message digest algorithms
        catch (NoSuchAlgorithmException e) {
            throw new RuntimeException(e);
        }
    }

    private static final char[] HEX_ARRAY = "0123456789ABCDEF".toCharArray();

    public static String bytesToHex(byte[] bytes) {
        char[] hexChars = new char[bytes.length * 2];
        for (int j = 0; j < bytes.length; j++) {
            int v = bytes[j] & 0xFF;
            hexChars[j * 2] = HEX_ARRAY[v >>> 4];
            hexChars[j * 2 + 1] = HEX_ARRAY[v & 0x0F];
        }
        return new String(hexChars);
    }

    // Driver code
    public static void main(String args[]) throws NoSuchAlgorithmException, InvalidKeySpecException, IOException, InvalidKeyException, NoSuchPaddingException, BadPaddingException, IllegalBlockSizeException, NoSuchProviderException, SignatureException
    {
        String cadena = "3c6f084f-3949-4236-a0bc-d85ff9e05495|MXN|10.0|Pago de prueba QR 5|Prueba 5|2021-06-07T17:04:56.900046+00:00";
        String signature = "hxkqkKaar5jstZMJeCK3Bv3IByGOZrVyb9t+kt1hEL7pt/FrvxATuc+9b/95lkqkeVSnK98/cD0xSs0p2fdkAhskHZJTHbTWu3bbNHWBpIXmqnRNzuhi7zP+tmwsaGJ830o1BL5Vyq5rvqq4ll/ILkJVCEbru4VwE/+0W7OWiETV4Nqe6M9Yhu09/+GtW0KCAgVaX8Yol3SgGGp8z6+T1WJ6hw6K5EIg34UfBujJzHfr+39LpBJvPO2JykGs1lwNrOaon+FYb8AzmVoRAu49VwJ380Gb3Wv6j1oy+O/8Ry3X0b8NY83JA9mdtz5/M0pIVvgqIcNjKH4KBuambSig1g==";

        String publicKeyContent8 = null;
        String file8 = "resource/dapp_public_pk8_prod.pem";
        Path path8 = Paths.get(file8);
        List<String> lines8 = Files.readAllLines(path8);

        publicKeyContent8 = lines8.toString().replaceAll("\\n", "").replace("[-----BEGIN PUBLIC KEY-----", "").replace("-----END PUBLIC KEY-----]", "").replaceAll(", ", "");

        KeyFactory kf8 = KeyFactory.getInstance("RSA");
        X509EncodedKeySpec keySpecX5098 = new X509EncodedKeySpec(Base64.getDecoder().decode(publicKeyContent8));
        RSAPublicKey pubKey8 = (RSAPublicKey) kf8.generatePublic(keySpecX5098);

        final Signature sig = Signature.getInstance( "SHA512withRSA");
        sig.initVerify( pubKey8 );
        sig.update( cadena.getBytes("utf8") );
        final byte[] signatureBytes = Base64.getDecoder().decode(signature);
        System.out.println("\n*Signature decode Base64*: " + bytesToHex(signatureBytes));
        System.out.println("\n*Verificar*: " + sig.verify( signatureBytes ));
    }
}

import base64
import os

from Cryptodome.Hash import SHA512
from Cryptodome.PublicKey import RSA
from Cryptodome.Signature import pkcs1_15

def test_signature():
	cadena = "3c6f084f-3949-4236-a0bc-d85ff9e05495|MXN|10.0|Pago de prueba QR 5|Prueba 5|2021-06-07T17:04:56.900046+00:00"
	hash_cadena = SHA512.new(cadena.encode("utf-8"))

	signature = "hxkqkKaar5jstZMJeCK3Bv3IByGOZrVyb9t+kt1hEL7pt/FrvxATuc+9b/95lkqkeVSnK98/cD0xSs0p2fdkAhskHZJTHbTWu3bbNHWBpIXmqnRNzuhi7zP+tmwsaGJ830o1BL5Vyq5rvqq4ll/ILkJVCEbru4VwE/+0W7OWiETV4Nqe6M9Yhu09/+GtW0KCAgVaX8Yol3SgGGp8z6+T1WJ6hw6K5EIg34UfBujJzHfr+39LpBJvPO2JykGs1lwNrOaon+FYb8AzmVoRAu49VwJ380Gb3Wv6j1oy+O/8Ry3X0b8NY83JA9mdtz5/M0pIVvgqIcNjKH4KBuambSig1g=="
	b64_bytes = signature.encode("utf-8")
	byte_str = base64.b64decode(b64_bytes)

	path = os.path.join("MyPath", 'dapp_public_prod.pem')
	with open(path, 'r') as myfile:
		key_data = myfile.read()
	key = RSA.importKey(key_data)
    	pkcs1_15.new(key).verify(hash_cadena, byte_str)