Question

I know that there is code like this:
http://www.java2s.com/Code/Android/Security/RSAencryptdecryptfunctionRSAECBPKCS1Padding.htm

/*
 Copyright (c) 2010, Sungjin Han <[e-mail]>
 All rights reserved.

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  * Redistributions of source code must retain the above copyright notice,
    this list of conditions and the following disclaimer.
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    notice, this list of conditions and the following disclaimer in the
    documentation and/or other materials provided with the distribution.
  * Neither the name of meinside nor the names of its contributors may be
    used to endorse or promote products derived from this software without
    specific prior written permission.

 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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 */

//package org.andlib.helpers;
public static KeyPair generateRsaKeyPair(int keySize, BigInteger publicExponent)
{
KeyPair keys = null;
try
{
  KeyPairGenerator keyGen = KeyPairGenerator.getInstance("RSA");
  RSAKeyGenParameterSpec spec = new RSAKeyGenParameterSpec(keySize, publicExponent);
  keyGen.initialize(spec);
  keys = keyGen.generateKeyPair();
}
catch(Exception e)
{
//  Logger.e(e.toString());
}
return keys;


}



/**
   * generates a RSA public key with given modulus and public exponent
   * 
   * @param modulus (must be positive? don't know exactly)
   * @param publicExponent
   * @return
   */
  public static PublicKey generateRsaPublicKey(BigInteger modulus, BigInteger publicExponent)
  {
    try
    {
      return KeyFactory.getInstance("RSA").generatePublic(new RSAPublicKeySpec(modulus,     publicExponent));
    }
    catch(Exception e)
    {
    //  Logger.e(e.toString());
    }
    return null;
  }

  /**
   * generates a RSA private key with given modulus and private exponent
   * 
   * @param modulus (must be positive? don't know exactly)
   * @param privateExponent
   * @return
   */
  public static PrivateKey generateRsaPrivateKey(BigInteger modulus, BigInteger privateExponent)
  {
    try
    {
      return KeyFactory.getInstance("RSA").generatePrivate(new RSAPrivateKeySpec(modulus, privateExponent));
    }
    catch(Exception e)
    {
    //  Logger.e(e.toString());
    }
    return null;
  }

  /**
   * RSA encrypt function (RSA / ECB / PKCS1-Padding)
   * 
   * @param original
   * @param key
   * @return
   */
  public static byte[] rsaEncrypt(byte[] original, PublicKey key)
  {
    try
    {
      Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
      cipher.init(Cipher.ENCRYPT_MODE, key);
      return cipher.doFinal(original);
    }
    catch(Exception e)
    {
    //  Logger.e(e.toString());
    }
    return null;
  }

  /**
   * RSA decrypt function (RSA / ECB / PKCS1-Padding)
   * 
   * @param encrypted
   * @param key
   * @return
   */
  public static byte[] rsaDecrypt(byte[] encrypted, PrivateKey key)
  {
    try
    {
      Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
      cipher.init(Cipher.DECRYPT_MODE, key);
      return cipher.doFinal(encrypted);
    }
    catch(Exception e)
    {
    //  Logger.e(e.toString());
    }
    return null;
  }

Some questions:

Are there side attacks for the code linked above, or is it secure?

If the answer to the first question is no, then is there a module which takes care of side attacks?

I am using Froyo and have tried googling for a while now. All help is appreciated, thanks.

Answer 1

What do you mean by ‘side attacks’? Whether it’s secure or not, depends on many things, mostly on how you use it, and what are you encrypting/decrypting. Funny thing is, the license is longer than the code, and code basically does nothing special: just swallowing exceptions…

This has little to do with Android, BTW.