Android™

ebay: Add Digital Signature to HTTP Request

See more eBay Examples

Demonstrates how to add a digital signature to an ebay HTTP request. Android™

// Important: Don't forget to include the call to System.loadLibrary
// as shown at the bottom of this code sample.
package com.test;

import android.app.Activity;
import com.chilkatsoft.*;

import android.widget.TextView;
import android.os.Bundle;

public class SimpleActivity extends Activity {

  private static final String TAG = "Chilkat";

  // Called when the activity is first created.
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    boolean success = false;

    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    // Note: Ebay provides a Key Management API
    // See https://developer.ebay.com/api-docs/developer/key-management/overview.html

    // The following test keys can be used: 
    // 
    // Ed25519 
    // 
    // Private Key:
    // 
    // -----BEGIN PRIVATE KEY-----
    // MC4CAQAwBQYDK2VwBCIEIJ+DYvh6SEqVTm50DFtMDoQikTmiCqirVv9mWG9qfSnF
    // -----END PRIVATE KEY-----

    String strPrivateKey = "MC4CAQAwBQYDK2VwBCIEIJ+DYvh6SEqVTm50DFtMDoQikTmiCqirVv9mWG9qfSnF";

    // 
    // Public Key:
    // 
    // -----BEGIN PUBLIC KEY-----
    // MCowBQYDK2VwAyEAJrQLj5P/89iXES9+vFgrIy29clF9CC/oPPsw3c5D0bs=
    // -----END PUBLIC KEY-----

    String strPublicKey = "MCowBQYDK2VwAyEAJrQLj5P/89iXES9+vFgrIy29clF9CC/oPPsw3c5D0bs=";

    // This example assumes you got a JWE for your given private key from the Ebay Key Management REST API.
    // This JWE is just for example:
    String strJwe = "eyJ6aXAiOiJERUYiLCJlbmMiOiJBMjU2R0NNIiwidGFnIjoiSXh2dVRMb0FLS0hlS0Zoa3BxQ05CUSIsImFsZyI6IkEyNTZHQ01LVyIsIml2IjoiaFd3YjNoczk2QzEyOTNucCJ9.2o02pR9SoTF4g_5qRXZm6tF4H52TarilIAKxoVUqjd8.3qaF0KJN-rFHHm_P.AMUAe9PPduew09mANIZ-O_68CCuv6EIx096rm9WyLZnYz5N1WFDQ3jP0RBkbaOtQZHImMSPXIHVaB96RWshLuJsUgCKmTAwkPVCZv3zhLxZVxMXtPUuJ-ppVmPIv0NzznWCOU5Kvb9Xux7ZtnlvLXgwOFEix-BaWNomUAazbsrUCbrp514GIea3butbyxXLNi6R9TJUNh8V2uan-optT1MMyS7eMQnVGL5rYBULk.9K5ucUqAu0DqkkhgubsHHw";

    CkStringBuilder sbBody = new CkStringBuilder();
    sbBody.Append("{\"hello\": \"world\"}");

    Log.i(TAG, "Body of request:");
    Log.i(TAG, sbBody.getAsString());

    // -------------------------------------------------
    // Build the signature base string...

    CkStringBuilder sbSigBase = new CkStringBuilder();

    sbSigBase.Append("\"content-digest\": sha-256=:");
    sbSigBase.Append(sbBody.getHash("sha256","base64","utf-8"));
    sbSigBase.Append(":\n");

    sbSigBase.Append("\"x-ebay-signature-key\": ");
    sbSigBase.Append(strJwe);
    sbSigBase.Append("\n");

    sbSigBase.Append("\"@method\": POST\n");

    // This is the path part of the URL without query params...
    sbSigBase.Append("\"@path\": ");
    sbSigBase.Append("/verifysignature");
    sbSigBase.Append("\n");

    // The is the domain, such as "api.ebay.com" w/ port if the port is something unusual.
    // In this example, we're testing against a local docker test server (see the info at https://developer.ebay.com/develop/guides/digital-signatures-for-apis)
    // Normally, I think it would just be "api.ebay.com" instead of "localhost:8080".
    sbSigBase.Append("\"@authority\": ");
    sbSigBase.Append("localhost:8080");
    sbSigBase.Append("\n");

    sbSigBase.Append("\"@signature-params\": ");

    CkStringBuilder sbSigInput = new CkStringBuilder();
    sbSigInput.Append("(\"content-digest\" \"x-ebay-signature-key\" \"@method\" \"@path\" \"@authority\")");
    sbSigInput.Append(";created=");

    CkDateTime dt = new CkDateTime();
    dt.SetFromCurrentSystemTime();
    String unixTimeNow = dt.getAsUnixTimeStr(false);
    sbSigInput.Append(unixTimeNow);

    sbSigBase.AppendSb(sbSigInput);

    // -------------------------------------------------
    // Sign the signature base string using the Ed25519 private key

    CkBinData bdPrivKey = new CkBinData();
    bdPrivKey.AppendEncoded(strPrivateKey,"base64");

    CkPrivateKey privKey = new CkPrivateKey();
    success = privKey.LoadAnyFormat(bdPrivKey,"");
    if (success == false) {
        Log.i(TAG, privKey.lastErrorText());
        return;
        }

    CkBinData bdToBeSigned = new CkBinData();
    bdToBeSigned.AppendSb(sbSigBase,"utf-8");

    CkEdDSA eddsa = new CkEdDSA();
    String sigBase64 = eddsa.signBdENC(bdToBeSigned,"base64",privKey);
    if (eddsa.get_LastMethodSuccess() == false) {
        Log.i(TAG, eddsa.lastErrorText());
        return;
        }

    Log.i(TAG, "sigBase64:");
    Log.i(TAG, sigBase64);

    // ----------------------------------------------------------
    // Send the JSON POST

    CkHttp http = new CkHttp();

    http.SetRequestHeader("x-ebay-signature-key",strJwe);

    CkStringBuilder sbContentDigestHdr = new CkStringBuilder();
    sbContentDigestHdr.Append("sha-256=:");
    sbContentDigestHdr.Append(sbBody.getHash("sha256","base64","utf-8"));
    sbContentDigestHdr.Append(":");
    http.SetRequestHeader("Content-Digest",sbContentDigestHdr.getAsString());

    CkStringBuilder sbSigHdr = new CkStringBuilder();
    sbSigHdr.Append("sig1=:");
    sbSigHdr.Append(sigBase64);
    sbSigHdr.Append(":");
    http.SetRequestHeader("Signature",sbSigHdr.getAsString());

    sbSigInput.Prepend("sig1=");
    http.SetRequestHeader("Signature-Input",sbSigInput.getAsString());

    // Add this header to make eBay actually check the signature.
    http.SetRequestHeader("x-ebay-enforce-signature","true");

    // Set the OAuth2 access token to add the "Authorization: Bearer <access_token>" to the header.
    http.put_AuthToken("your_oauth2_access_token");

    // The signature base string constructed above is valid if we send this POST to "http://localhost:8080/verifysignature"
    // Normally, you'll send your POST to some api.ebay.com endpoint.
    String url = "http://localhost:8080/verifysignature";

    String jsonStr = sbBody.getAsString();
    CkHttpResponse resp = new CkHttpResponse();
    success = http.HttpStr("POST","http://localhost:8080/verifysignature",jsonStr,"utf-8","application/json",resp);
    if (success == false) {
        Log.i(TAG, http.lastErrorText());
        return;
        }

    Log.i(TAG, "Response status code: " + String.valueOf(resp.get_StatusCode()));
    Log.i(TAG, "Response body:");
    Log.i(TAG, resp.bodyStr());

  }

  static {
      System.loadLibrary("chilkat");

      // Note: If the incorrect library name is passed to System.loadLibrary,
      // then you will see the following error message at application startup:
      //"The application <your-application-name> has stopped unexpectedly. Please try again."
  }
}