Android™

RSA Encrypt and Decrypt Strings

See more RSA Examples

_LANGUAGE_ sample code to RSA public-key encrypt and decrypt strings using public and private keys. 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 assumes the Chilkat API to have been previously unlocked.
    //  See Global Unlock Sample for sample code.

    CkRsa rsa = new CkRsa();

    //  This example also generates the public and private
    //  keys to be used in the RSA encryption.
    //  Normally, you would generate a key pair once,
    //  and distribute the public key to your partner.
    //  Anything encrypted with the public key can be
    //  decrypted with the private key.  The reverse is 
    //  also true: anything encrypted using the private
    //  key can be decrypted using the public key.

    //  Generate a 2048-bit key.  Chilkat RSA supports
    //  key sizes ranging from 512 bits to 4096 bits.
    CkPrivateKey privKey = new CkPrivateKey();
    success = rsa.GenKey(2048,privKey);
    if (success == false) {
        Log.i(TAG, rsa.lastErrorText());
        return;
        }

    CkPublicKey pubKey = new CkPublicKey();
    privKey.ToPublicKey(pubKey);

    String plainText = "Encrypting and decrypting should be easy!";

    //  Start with a new RSA object to demonstrate that all we
    //  need are the keys previously exported:
    CkRsa rsaEncryptor = new CkRsa();

    //  Encrypted output is always binary.  In this case, we want
    //  to encode the encrypted bytes in a printable string.
    //  Our choices are "hex", "base64", "url", "quoted-printable".
    rsaEncryptor.put_EncodingMode("hex");

    //  We'll encrypt with the public key and decrypt with the private
    //  key.
    success = rsaEncryptor.UsePublicKey(pubKey);

    boolean usePrivateKey = false;
    String encryptedStr = rsaEncryptor.encryptStringENC(plainText,usePrivateKey);
    Log.i(TAG, encryptedStr);

    //  Now decrypt:
    CkRsa rsaDecryptor = new CkRsa();

    rsaDecryptor.put_EncodingMode("hex");
    success = rsaDecryptor.UsePrivateKey(privKey);

    usePrivateKey = true;
    String decryptedStr = rsaDecryptor.decryptStringENC(encryptedStr,usePrivateKey);

    Log.i(TAG, decryptedStr);

  }

  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."
  }
}