(Android™) RSA Encrypt RSA/ECB/OAEPWithSHA1AndMGF1Padding

Demonstrates how to RSA encrypt using RSA/ECB/OAEPWithSHA1AndMGF1Padding. Also demonstrates RSA/ECB/OAEPWithSHA-256AndMGF1Padding. Both of these terms are from Java's JCE. Note: In this context, "ECB" doesn't actually mean anything. It's a symmetric cipher mode that doesn't apply (or make sense) in this context.

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();

    // First load a public key object with a public key.
    // In this case, we'll load it from a file.
    CkPublicKey pubkey = new CkPublicKey();
    boolean success = pubkey.LoadFromFile("qa_data/pem/rsa_public.pem");
    if (success != true) {
        Log.i(TAG, pubkey.lastErrorText());
        return;
        }

    // RSA encryption is limited to small amounts of data. The limit
    // is typically a few hundred bytes and is based on the key size and
    // padding (OAEP vs. PKCS1_5).  RSA encryption is typically used for
    // encrypting hashes or symmetric (bulk encryption algorithm) secret keys.
    String plainText = "Time is an illusion. Lunchtime doubly so.";

    // Import the public key to be used for encrypting.
    success = rsa.ImportPublicKeyObj(pubkey);

    // To get OAEP padding, set the OaepPadding property:
    rsa.put_OaepPadding(true);

    // To use SHA1 or SHA-256, set the OaepHash property
    rsa.put_OaepHash("sha256");
    // for SHA1 --
    rsa.put_OaepHash("sha1");

    // Indicate we'll want hex output
    rsa.put_EncodingMode("hex");

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

    // -------------------------------------------------
    // Now decrypt with the matching private key.
    CkRsa rsa2 = new CkRsa();

    CkPrivateKey privKey = new CkPrivateKey();
    success = privKey.LoadEncryptedPem("qa_data/pem/rsa_passwd.pem","passwd");
    if (success != true) {
        Log.i(TAG, privKey.lastErrorText());
        return;
        }

    success = rsa2.ImportPrivateKeyObj(privKey);

    // Make sure we have the same settings used for encryption.
    rsa2.put_OaepPadding(true);
    rsa2.put_EncodingMode("hex");
    rsa2.put_OaepHash("sha1");

    String originalStr = rsa2.decryptStringENC(encryptedStr,true);

    Log.i(TAG, originalStr);

  }

  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."
  }
}