Android™

Get Public Key from CSR

See more CSR Examples

Demonstrates how to get the public key from a CSR. 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 requires the Chilkat API to have been previously unlocked.
    //  See Global Unlock Sample for sample code.

    CkPem pem = new CkPem();

    //  No password is required.  Pass an empty password string..
    String noPassword = "";
    success = pem.LoadPemFile("qa_data/csr/csr2.pem",noPassword);
    if (success != true) {
        Log.i(TAG, pem.lastErrorText());
        return;
        }

    String strBase64 = pem.getEncodedItem("csr","","base64",0);

    CkAsn asn = new CkAsn();
    success = asn.LoadEncoded(strBase64,"base64");
    if (success != true) {
        Log.i(TAG, asn.lastErrorText());
        return;
        }

    //  Convert the ASN.1 to XML.
    CkXml xml = new CkXml();
    success = xml.LoadXml(asn.asnToXml());
    Log.i(TAG, xml.getXml());
    Log.i(TAG, "----");

    String strModulusHex = xml.getChildContent("bits");
    Log.i(TAG, "strModulusHex = " + strModulusHex);
    Log.i(TAG, "----");

    //  We need the modulus as base64.
    CkBinData bd = new CkBinData();
    bd.AppendEncoded(strModulusHex,"hex");
    String modulus64 = bd.getEncoded("base64");
    Log.i(TAG, "modulus64 = " + modulus64);
    Log.i(TAG, "----");

    //  Build the XML for the public key.
    CkXml xmlPubKey = new CkXml();
    xmlPubKey.put_Tag("RSAPublicKey");
    xmlPubKey.UpdateChildContent("Modulus",modulus64);
    //  The RSA exponent will always be decimal 65537 (base64 = AQAB)
    xmlPubKey.UpdateChildContent("Exponent","AQAB");

    Log.i(TAG, "RSA public key as XML:");
    Log.i(TAG, xmlPubKey.getXml());
    Log.i(TAG, "----");

    //  Load the XML into a Chilkat public key object.
    CkPublicKey pubkey = new CkPublicKey();
    success = pubkey.LoadFromString(xmlPubKey.getXml());
    if (success != true) {
        Log.i(TAG, pubkey.lastErrorText());
        return;
        }

    //  Show the public key as PEM.
    boolean preferPkcs1 = true;
    Log.i(TAG, pubkey.getPem(preferPkcs1));

  }

  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."
  }
}