(Android™) Generate RSA Key and Export to PKCS1 / PKCS8

Android™ example code showing how to generate an RSA public/private key and save to PKCS1 and PKCS8 format files. In a PKCS1 or PKCS8 formatted file, the key is stored in binary ASN.1 format (and ASN.1 is itself written according to DER -- Distinguished Encoding Rules). A PEM file simply contains the binary ASN.1 base64 encoded and delimited by BEGIN/END lines. PKCS1 format files are never encrypted. PKCS8 can be encrypted or unencrypted. Public keys are never encrypted (there is no need). Private keys *should* always be encrypted - unless perhaps the unencrypted private key is obtained and itself stored in some sort of secure place.

Chilkat Android™ Downloads Android™ Java Libraries Android C/C++ Libraries

// 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);

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

    CkRsa rsa = new CkRsa();

    // Generate a 2048-bit key.  Chilkat RSA supports
    // key sizes ranging from 512 bits to 8192 bits.
    boolean success = rsa.GenerateKey(2048);
    if (success != true) {
        Log.i(TAG, rsa.lastErrorText());
        return;
        }

    // Get the public and private key parts:
    CkPublicKey pubKey = rsa.ExportPublicKeyObj();
    CkPrivateKey privKey = rsa.ExportPrivateKeyObj();

    // Get the public key as a PKCS8 PEM string
    String pubKeyPem = pubKey.getPem(false);
    Log.i(TAG, pubKeyPem);

    // Get the public key in PKCS8 format, in a Base64 encoded string.
    String pubKeyPkcs8Base64 = pubKey.getEncoded(false,"base64");
    Log.i(TAG, pubKeyPkcs8Base64);

    // Get the public key in PKCS1 format, in a Base64 encoded string.
    String pubKeyPkcs1Base64 = pubKey.getEncoded(true,"base64");
    Log.i(TAG, pubKeyPkcs1Base64);

    // Get the private key in a PKCS8 PEM string.
    String privKeyPem = privKey.getPkcs8Pem();
    Log.i(TAG, privKeyPem);

    // Get the private key in a PKCS8 encrypted PEM string.
    String privKeyEncPem = privKey.getPkcs8EncryptedPem("myPassword");
    Log.i(TAG, privKeyEncPem);

    // Get the private key in PKCS1 Base64 format
    String privKeyPkcs1Base64 = privKey.getPkcs1ENC("base64");
    Log.i(TAG, privKeyPkcs1Base64);

    // Get the private key in PKCS8 Base64 format
    String privKeyPkcs8Base64 = privKey.getPkcs8ENC("base64");
    Log.i(TAG, privKeyPkcs8Base64);

    // Save to PKCS1 / PKCS8 / PEM files...

    // Save the public key to PKCS8 binary DER
    success = pubKey.SaveDerFile(false,"pubKey_pkcs8.der");

    // Save the public key to PKCS1 binary DER
    success = pubKey.SaveDerFile("pubKey_pkcs1.der");

    // Save the private key to unencrypted binary PKCS1 DER.
    // Note: PKCS1 is never found in an encrypted format. 
    success = privKey.SavePkcs1File("privKey_pkcs1.der");

    // Save the private key to unencrypted binary PKCS8
    success = privKey.SavePkcs8File("privKey_pkcs8.der");

    // Save the private key to encrypted binary PKCS8
    success = privKey.SavePkcs8EncryptedFile("myPassword","privKey_enc_pkcs8.der");

    // Save the private key to unencrypted PKCS8 PEM
    success = privKey.SavePkcs8PemFile("privKey.pem");

    // Save the private key to encrypted PKCS8 PEM
    success = privKey.SavePkcs8EncryptedPemFile("myPassword","privKey_enc.pem");


  }

  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."
  }
}