Purchase Data

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# This is just an example of pseudocode
# You should implement it according to
# your back end programming language.

privateKey = readPrivateKeyFile(PATH + PrivateKeyFile)
orderBytes = orderJsonString.readBytes(UTF-8)
orderSignature = rsaSha256SignerLibrary.sign(privateKey, orderBytes)

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const { sign } = require("crypto");
const { existsSync, readFileSync } = require("fs");
const { resolve } = require("path");

(function main() {
  const purchaseData = JSON.stringify({
    version: "v1.1.0",
    country: "US",
    shopperCartId: "l93hyghr9hojqinx",
    merchantOrderId: "l93hyghr4yty9jgm",
    shopperEmail: "hello@zenki.fi",
    purchaseSummary: {
      currency: "USD",
      totalItemsAmount: "0.5",
      shipmentAmount: "0.25",
      subtotalAmount: "0.75",
      taxesAmount: "0.125",
      localTaxesAmount: "0.125",
      importCosts: "0.125",
      discountAmount: "0.25",
      additionalCharges: {
        perquisite: "0.125",
      },
      grandTotalAmount: "1",
    },
    serviceType: "SERVICE",
    items: [
      {
        itemId: "l93hyghr5hp3lxcp",
        price: "0.5",
        quantity: "1",
        productName: "Javascript",
        thumbnailUrl:
          "https://tshirts.boutique/wp-content/uploads/2022/09/12124-65.jpg",
        metadata: {
          size: "L",
        },
      },
    ],
    zenkipayKey:
      "e77e5b666253243e9179ff4d33fe364ec88aacf9240e5e7673e474255e4a900c",
    metadata: {
      anotherId: "l93hyghrcjs78929",
    },
  });
  console.log("\nPurchase data stringified:\n%s", purchaseData);
  const zenkipaySignature = signPurchaseData(purchaseData);
  console.log("\nZenkipay signature:\n%s", zenkipaySignature);

  process.exit();
})();

function signPurchaseData(purchaseData) {
  const privateKey = getPrivateKey();
  const signature = sign("sha256", Buffer.from(purchaseData), {
    key: privateKey,
  });
  return signature.toString("base64");
}

function getPrivateKey() {
  const filepath = resolve(__dirname, "keys", "private.pem");
  if (existsSync(filepath)) {
    return readFileSync(filepath, { encoding: "utf-8" });
  }
  throw new Error(`Key not found: ${filepath}`);
}

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/**
 * @param string $purchase_data
 *
 * @return string
 */
public function generateSignature($purchase_data)
{
  $private_key_file = file_get_contents('/path/to/the/private-key.pem');
  $private_key = openssl_pkey_get_private($private_key_file);
  openssl_sign($purchase_data, $signature, $private_key, 'RSA-SHA256');
  return base64_encode($signature);
}

/**
 * @param string $purchase_data
 * @param string $signature
 *
 * @return boolean Returns TRUE if the signature is correct, FALSE if it's incorrect
 */
public function verifySignature($purchase_data, $signature)
{
  $public_key_file = file_get_contents('/path/to/the//public-key.pem');
  $public_key = openssl_pkey_get_public($public_key_file);
  $decoded_siganture = base64_decode($signature);
  $verify = openssl_verify($purchase_data, $decoded_siganture, $public_key, 'RSA-SHA256');
  return $verify == 1;
}

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import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.security.*;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
import java.util.Base64;

/**
 * Snippet to sign message with <strong>PKCS #8 private key</strong>.
 * <p><strong>Note: </strong></p> Changes might be required if your private key is in a format different that <strong>PKCS #8</strong>.
 */
public class ZenkiSnippet {
    private static final String BEGIN_PRIVATE_KEY = "-----BEGIN PRIVATE KEY-----";
    private static final String END_PRIVATE_KEY = "-----END PRIVATE KEY-----";
    private static final String EMPTY_STRING = "";
    private static final String BREAK_LINE = "\n";

    /**
     * Sample base64 private key (<strong>PKCS #8</strong>) format.
     **/
    private static final String BASE_64_PRIVATE_KEY = "-----BEGIN PRIVATE KEY-----\n" +
            "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\n" +
            "-----END PRIVATE KEY-----";

    /**
     * Path for sample private key file (<strong>PKCS #8</strong>) format.
     **/
    private static final String PRIVATE_KEY_FILE_PATH = "/path/to/my/file";

    // Sample JSON purchase data.
    private static final String JSON_PURCHASE_DATA = "{\"version\":\"v1.1.0\",\"country\":\"US\",\"shopperCartId\":\"l93hyghr9hojqinx\",\"merchantOrderId\":\"l93hyghr4yty9jgm\",\"shopperEmail\":\"hello@zenki.fi\",\"purchaseSummary\":{\"currency\":\"USD\",\"totalItemsAmount\":\"0.5\",\"shipmentAmount\":\"0.25\",\"subtotalAmount\":\"0.75\",\"taxesAmount\":\"0.125\",\"localTaxesAmount\":\"0.125\",\"importCosts\":\"0.125\",\"discountAmount\":\"0.25\",\"additionalCharges\":{\"perquisite\":\"0.125\"},\"grandTotalAmount\":\"1\"},\"serviceType\":\"SERVICE\",\"items\":[{\"itemId\":\"l93hyghr5hp3lxcp\",\"price\":\"0.5\",\"quantity\":\"1\",\"productName\":\"Javascript\",\"thumbnailUrl\":\"https:\/\/tshirts.boutique\/wp-content\/uploads\/2022\/09\/12124-65.jpg\",\"metadata\":{\"size\":\"L\"}}],\"zenkipayKey\":\"e77e5b666253243e9179ff4d33fe364ec88aacf9240e5e7673e474255e4a900c\",\"metadata\":{\"anotherId\":\"l93hyghrcjs78929\"}}";

    public static void main(String[] args) throws IOException, InvalidKeySpecException, NoSuchAlgorithmException, SignatureException, InvalidKeyException {

        System.out.println("Signature: " + signMessageWithPkFromFile()); // Snippet to sing message getting private key from file.
        System.out.println("Signature: " + signMessageWithPkBase64()); // Snippet to sing message getting private key from base64 string.
    }

    public static String signMessageWithPkFromFile() throws IOException, InvalidKeySpecException, NoSuchAlgorithmException, SignatureException, InvalidKeyException {
        PrivateKey privateKey = getPKFromFile();
        Signature signatureProvider = Signature.getInstance("SHA256withRSA");
        signatureProvider.initSign(privateKey); // Private key
        signatureProvider.update(JSON_PURCHASE_DATA.getBytes()); // Message to sign (in bytes)

        byte[] signature = signatureProvider.sign(); // Signature

        return Base64.getEncoder().encodeToString(signature); // Signature encoded in base64
    }

    public static String signMessageWithPkBase64() throws NoSuchAlgorithmException, InvalidKeySpecException, InvalidKeyException, SignatureException {
        PrivateKey privateKey = getPKFromBase64String();

        Signature signatureProvider = Signature.getInstance("SHA256withRSA");
        signatureProvider.initSign(privateKey); // Private key
        signatureProvider.update(JSON_PURCHASE_DATA.getBytes()); // Message to sign (in bytes)

        byte[] signature = signatureProvider.sign(); // Signature

        return Base64.getEncoder().encodeToString(signature); // Signature encoded in base64
    }

    private static PrivateKey getPKFromFile() throws IOException, InvalidKeySpecException, NoSuchAlgorithmException {
        byte[] privateKey = Files.readAllBytes(Paths.get(PRIVATE_KEY_FILE_PATH)); // Getting file from filesystem

        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(privateKey, "RSA");
        KeyFactory kf = KeyFactory.getInstance("RSA");
        return kf.generatePrivate(keySpec);
    }

    private static PrivateKey getPKFromBase64String() throws NoSuchAlgorithmException, InvalidKeySpecException {
        String formattedKeyString = removePrivateKeyHeaders(BASE_64_PRIVATE_KEY);
        PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(Base64.getDecoder().decode(formattedKeyString), "RSA");
        KeyFactory kf = KeyFactory.getInstance("RSA");
        return kf.generatePrivate(keySpec);
    }

    private static String removePrivateKeyHeaders(String keyString) {
        return keyString
                .replace(BREAK_LINE, EMPTY_STRING)
                .replace(BEGIN_PRIVATE_KEY, EMPTY_STRING)
                .replace(END_PRIVATE_KEY, EMPTY_STRING);

    }
}