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AES Initialization Vector randomization

I am trying to reuse an AES implementation with Initialization Vector. So far I am only implementing the part where data is being encrypted on the android application and being decrypted on the php server. However, the algorithm has a major loophole, that the Initialization Vector is constant, which I just recently found out is a major security flaw. Unfortunately I have already implemented it on every single activity of my application and all scripts on the server side.
I wanted to know if there was a way to modify this code so that the initialization vector is randomized, and some way to send that vector to the server (or vice versa), so that every time the message is encrypted the pattern keeps changing. Here are my codes for Android and PHP:
Android:
package com.fyp.merchantapp;
// This file and its contents have been taken from http://www.androidsnippets.com/encrypt-decrypt-between-android-and-php.html
//Ownership has been acknowledged
import java.security.NoSuchAlgorithmException;
import javax.crypto.Cipher;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
public class MCrypt {
static char[] HEX_CHARS = {'0','1','2','3','4','5','6','7','8','9','a','b','c','d','e','f'};
private String iv = "MyNameIsHamza100";//(IV)
private IvParameterSpec ivspec;
private SecretKeySpec keyspec;
private Cipher cipher;
private String SecretKey = "MyNameIsBilal100";//(SECRETKEY)
public MCrypt()
{
ivspec = new IvParameterSpec(iv.getBytes());
keyspec = new SecretKeySpec(SecretKey.getBytes(), "AES");
try {
cipher = Cipher.getInstance("AES/CBC/NoPadding");
} catch (NoSuchAlgorithmException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (NoSuchPaddingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public byte[] encrypt(String text) throws Exception
{
if(text == null || text.length() == 0)
throw new Exception("Empty string");
byte[] encrypted = null;
try {
cipher.init(Cipher.ENCRYPT_MODE, keyspec, ivspec);
encrypted = cipher.doFinal(padString(text).getBytes());
} catch (Exception e)
{
throw new Exception("[encrypt] " + e.getMessage());
}
return encrypted;
}
public byte[] decrypt(String code) throws Exception
{
if(code == null || code.length() == 0)
throw new Exception("Empty string");
byte[] decrypted = null;
try {
cipher.init(Cipher.DECRYPT_MODE, keyspec, ivspec);
decrypted = cipher.doFinal(hexToBytes(code));
//Remove trailing zeroes
if( decrypted.length > 0)
{
int trim = 0;
for( int i = decrypted.length - 1; i >= 0; i-- ) if( decrypted[i] == 0 ) trim++;
if( trim > 0 )
{
byte[] newArray = new byte[decrypted.length - trim];
System.arraycopy(decrypted, 0, newArray, 0, decrypted.length - trim);
decrypted = newArray;
}
}
} catch (Exception e)
{
throw new Exception("[decrypt] " + e.getMessage());
}
return decrypted;
}
public static String bytesToHex(byte[] buf)
{
char[] chars = new char[2 * buf.length];
for (int i = 0; i < buf.length; ++i)
{
chars[2 * i] = HEX_CHARS[(buf[i] & 0xF0) >>> 4];
chars[2 * i + 1] = HEX_CHARS[buf[i] & 0x0F];
}
return new String(chars);
}
public static byte[] hexToBytes(String str) {
if (str==null) {
return null;
} else if (str.length() < 2) {
return null;
} else {
int len = str.length() / 2;
byte[] buffer = new byte[len];
for (int i=0; i<len; i++) {
buffer[i] = (byte) Integer.parseInt(str.substring(i*2,i*2+2),16);
}
return buffer;
}
}
private static String padString(String source)
{
char paddingChar = 0;
int size = 16;
int x = source.length() % size;
int padLength = size - x;
for (int i = 0; i < padLength; i++)
{
source += paddingChar;
}
return source;
}
}
PHP:
<?php
class MCrypt
{
private $iv = 'MyNameIsHamza100'; #Same as in JAVA
private $key = 'MyNameIsBilal100'; #Same as in JAVA
function __construct()
{
}
/**
* #param string $str
* #param bool $isBinary whether to encrypt as binary or not. Default is: false
* #return string Encrypted data
*/
function encrypt($str, $isBinary = false)
{
$iv = $this->iv;
$str = $isBinary ? $str : utf8_decode($str);
$td = mcrypt_module_open('rijndael-128', ' ', 'cbc', $iv);
mcrypt_generic_init($td, $this->key, $iv);
$encrypted = mcrypt_generic($td, $str);
mcrypt_generic_deinit($td);
mcrypt_module_close($td);
return $isBinary ? $encrypted : bin2hex($encrypted);
}
/**
* #param string $code
* #param bool $isBinary whether to decrypt as binary or not. Default is: false
* #return string Decrypted data
*/
function decrypt($code, $isBinary = false)
{
$code = $isBinary ? $code : $this->hex2bin($code);
$iv = $this->iv;
$td = mcrypt_module_open('rijndael-128', ' ', 'cbc', $iv);
mcrypt_generic_init($td, $this->key, $iv);
$decrypted = mdecrypt_generic($td, $code);
mcrypt_generic_deinit($td);
mcrypt_module_close($td);
return $isBinary ? trim($decrypted) : utf8_encode(trim($decrypted));
}
protected function hex2bin($hexdata)
{
$bindata = '';
for ($i = 0; $i < strlen($hexdata); $i += 2) {
$bindata .= chr(hexdec(substr($hexdata, $i, 2)));
}
return $bindata;
}
}
?>

To directly answer your question: you can simply generate a random IV and prefix it to the ciphertext. You need to do this before encoding the ciphertext to hexadecimals. Then during decryption first decode, then "remove" the IV bytes, initialize the IV and finally decrypt the ciphertext to obtain the plaintext.
Note that the IV will always be 16 bytes for AES in CBC mode, so there is no direct need to include the IV length anywhere. I used quotes around "remove" as both IvParameterSpec as Cipher.doFinal accept buffers with offset and length; there is no need to copy the bytes to different arrays.
Notes:
keys should not be strings; lookup PBKDF's such as PBKDF2 to derive a key from a password or pass phrase;
CBC is generally vulnerable to padding oracle attacks; however, by keeping to PHP's zero padding you may have avoided attacks by accident;
CBC doesn't provide integrity protection, so note that adversaries may change the ciphertext without decryption failing;
if the underlying code that uses the text generates errors then you may be vulnerable to plaintext oracle attacks (padding oracle attacks are only part of the larger group of plaintext oracles);
your Java code is unbalanced; the encrypt and decrypt mode should either perform hex encoding / decoding or they should not;
the exception handling is of course not good (although that may be just for the example);
String#getBytes() will use UTF-8 on Android, but it may use Windows-1252 on Java SE on Windows, so this is prone to generating the wrong key if you're not careful - always define the character set to use.
To use a shared secret to communicate, try TLS in pre-shared secret mode, defined by one of the PSK_ cipher suites.

Android AES encryption with python AES encryption

I have created the following python code
import base64
from django.conf import settings
from Crypto.Cipher import AES
BS = 16
def pad(s):
return s + (BS - len(s) % BS) * chr(BS - len(s) % BS)
def unpad(s):
return s[0:-s[-1]]
class AESCipher:
def __init__(self):
self.key = settings.SECRET_KEY
def encrypt(self, raw):
raw = pad(raw)
iv = settings.SECRET_IV.encode('utf-8')
cipher = AES.new(self.key, AES.MODE_CBC, iv)
return base64.b64encode(cipher.encrypt(raw))
def decrypt(self, enc):
enc = base64.b64decode(enc)
iv = settings.SECRET_IV.encode('utf-8')
cipher = AES.new(self.key, AES.MODE_CBC, iv)
return unpad(cipher.decrypt(enc))
def encryptstring(self, raw):
raw = self.encrypt(raw)
raw = raw.decode('utf-8')
return raw
def decryptstring(self, raw):
raw = raw.encode('utf-8')
raw = self.decrypt(raw)
raw = raw.decode('utf-8')
return raw
This code returns a base64 encrypted string (i.e. VgRaS+J3MSmguabaf+9fJw==).
I have also created a java function, that should create the same thing, but it doesn't match.
public void login() {
SecretKeySpec keySpec;
IvParameterSpec ivSpec;
Cipher cipher;
String key = "";
String iv = "";
try {
keySpec = new SecretKeySpec(key.getBytes(), "AES");
ivSpec = new IvParameterSpec(iv.getBytes());
cipher = Cipher.getInstance("AES/CBC/NoPadding");
String test = "Test";
String newString = "";
char paddingChar = ' ';
int size = 16;
int x = test.length() % size;
int padLength = size - x;
for (int i = 0; i < padLength; i++) {
newString += paddingChar;
// test += paddingChar;
}
newString += test;
byte[] res;
cipher.init(Cipher.ENCRYPT_MODE, keySpec, ivSpec);
res = cipher.doFinal(newString.getBytes());
for(int i = 0; i < res.length; i++) {
System.out.print(res[i] + ", ");
}
System.out.println("");
System.out.println(bytesToHex(res));
String base = Base64.encodeToString(res, Base64.DEFAULT);
System.out.println(base);
// TODO: VgRaS+J3MSmguabaf+9fJw==
// OyuUHNsBQ3Zuy4UGY4fUdQ==
} catch (NoSuchPaddingException e) {
e.printStackTrace();
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
} catch (InvalidAlgorithmParameterException e) {
e.printStackTrace();
} catch (InvalidKeyException e) {
e.printStackTrace();
} catch (IllegalBlockSizeException e) {
e.printStackTrace();
} catch (BadPaddingException e) {
e.printStackTrace();
}
}
The result I get there is 2mdRXydTCAYG+Tp0kE/NoQ==. It looks similar, but it isn't. I have checked the keys, they are the same. I have swapped them around, to make sure that wasn't the problem either. I have tried different cipher modes (AES/CBC/ISO10126Padding and AES/CBC/PKCS5Padding) both without result. I have tried to do it with plain AES, no success either. I tried to get AES_128/CBC/NoPadding and AES_256/CBC/NoPadding to work, but for some reason it tells me java.security.NoSuchAlgorithmException: No provider found for AES_256/CBC/NoPadding.
I am lost, I hope someone can help! Thanks in advance!

As JamesKPolk pointed out, the padding was wrong. I have solved this by doing the following:
Python has the following
def pad(s):
return s.ljust(16, '0')
Java has the following
char paddingChar = '0';

why AES java decryption return extra characters?

Excuse me for bad English.
i use mcrypt which i get it from here MCrypt for php and java. in my android application i need php and java communicate securely so i get above mentioned AES.
the problem is when php sends encrypted data, java can decrypt it but some extra characters are included.
JAVA Code
import java.security.NoSuchAlgorithmException;
import javax.crypto.Cipher;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
public class MCrypt {
private String iv = "fedcba9876543210";//Dummy iv (CHANGE IT!)
private IvParameterSpec ivspec;
private SecretKeySpec keyspec;
private Cipher cipher;
private String SecretKey = "0123456789abcdef";//Dummy secretKey (CHANGE IT!)
public MCrypt()
{
ivspec = new IvParameterSpec(iv.getBytes());
keyspec = new SecretKeySpec(SecretKey.getBytes(), "AES");
try {
cipher = Cipher.getInstance("AES/CBC/NoPadding");
} catch (NoSuchAlgorithmException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (NoSuchPaddingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public byte[] encrypt(String text) throws Exception
{
if(text == null || text.length() == 0)
throw new Exception("Empty string");
byte[] encrypted = null;
try {
cipher.init(Cipher.ENCRYPT_MODE, keyspec, ivspec);
encrypted = cipher.doFinal(padString(text).getBytes());
} catch (Exception e)
{
throw new Exception("[encrypt] " + e.getMessage());
}
return encrypted;
}
public byte[] decrypt(String code) throws Exception
{
if(code == null || code.length() == 0)
throw new Exception("Empty string");
byte[] decrypted = null;
try {
cipher.init(Cipher.DECRYPT_MODE, keyspec, ivspec);
decrypted = cipher.doFinal(hexToBytes(code));
} catch (Exception e)
{
throw new Exception("[decrypt] " + e.getMessage());
}
return decrypted;
}
public static String bytesToHex(byte[] data)
{
if (data==null)
{
return null;
}
int len = data.length;
String str = "";
for (int i=0; i<len; i++) {
if ((data[i]&0xFF)<16)
str = str + "0" + java.lang.Integer.toHexString(data[i]&0xFF);
else
str = str + java.lang.Integer.toHexString(data[i]&0xFF);
}
return str;
}
public static byte[] hexToBytes(String str) {
if (str==null) {
return null;
} else if (str.length() < 2) {
return null;
} else {
int len = str.length() / 2;
byte[] buffer = new byte[len];
for (int i=0; i<len; i++) {
buffer[i] = (byte) Integer.parseInt(str.substring(i*2,i*2+2),16);
}
return buffer;
}
}
private static String padString(String source)
{
char paddingChar = ' ';
int size = 16;
int x = source.length() % size;
int padLength = size - x;
for (int i = 0; i < padLength; i++)
{
source += paddingChar;
}
return source;
}
}
the PHP code
<?php
class MCrypt
{
private $iv = 'fedcba9876543210'; #Same as in JAVA
private $key = '0123456789abcdef'; #Same as in JAVA
function __construct()
{
}
function encrypt($str) {
//$key = $this->hex2bin($key);
$iv = $this->iv;
$td = mcrypt_module_open('rijndael-128', '', 'cbc', $iv);
mcrypt_generic_init($td, $this->key, $iv);
$encrypted = mcrypt_generic($td, $str);
mcrypt_generic_deinit($td);
mcrypt_module_close($td);
return bin2hex($encrypted);
}
function decrypt($code) {
//$key = $this->hex2bin($key);
$code = $this->hex2bin($code);
$iv = $this->iv;
$td = mcrypt_module_open('rijndael-128', '', 'cbc', $iv);
mcrypt_generic_init($td, $this->key, $iv);
$decrypted = mdecrypt_generic($td, $code);
mcrypt_generic_deinit($td);
mcrypt_module_close($td);
return utf8_encode(trim($decrypted));
}
protected function hex2bin($hexdata) {
$bindata = '';
for ($i = 0; $i < strlen($hexdata); $i += 2) {
$bindata .= chr(hexdec(substr($hexdata, $i, 2)));
}
return $bindata;
}
}
so the scenario is java send data (simple text) in JSON format to PHP , php extract the data , encrypt it and finally echo it in JSON format
PHP call:
<?php
$data =json_decode(file_get_contents('php://input'), true);
$data=$data["request"];
require_once "encryption.php";
$etool=new MCrypt();
$data=$etool->encrypt($data);
$array=array('data'=>$data);
echo json_encode($array);
JAVA code:
//sb is StringBuilder
JSONObject j=new JSONObject(sb.toString());
encryption etool=new encryption();
result=j.get("data").toString();
result= new String(etool.decrypt( result ));
Log.d("success remote ",result );
the result is:
example������
and if i use Farsi/Arabic word it get worse
like this-> درود����������������
in addition, i checked other questions but i could not get the answer.
AES encryption, got extra trash characters in decrypted file and
PHP MCRYPT encrypt/decrypt returns invisible strange characters?
thank you in advance!

AES encrypt in blocks of 16 bytes. If your input ain't a multiple of 16 bytes, a padding scheme is needed. As you have not specified any padding option for Mcrypt, it uses "zero padding".
In your Java code you specify "NoPadding" when you instantiate your Cipher:
cipher = Cipher.getInstance("AES/CBC/NoPadding");
So Java considers the padding done by php to be part of the encrypted data.
You just need to ensure that your php and Java code uses the same padding scheme.

I think this is binary data which can not be displayed.
Have you tried to use base64 to convert it to a regular string before sending it to the php script?
In the php script then you do following to decode the base64 string.
$data=base64_decode($data["request"])

PHP + Android XML Encryption/Decryption

I have an app that is downloading and parsing an xml into an sql database. My problem is that the data from the xml once the app is deployed could easily be scraped and other people could use my hard earned data for their own evil purposes/apps. Basically I need to encrypt the xml using php, and then decrypt it using android. I've seen a couple of php classes that make it easy to encrypt but I'm not entirely sure what method to encrypt would be compatible with android.
Edit after solution:
At first I thought I had to ignore brackets for some reason and was going to iterate through all the text and spit out formatted xml lol. Much simpler than that.
$mcrypt = new MCrypt();
$datainxml = file_get_contents("data.xml");
$cipher = $mcrypt->encrypt($value);
echo $cipher;

The following code might help you. Using this you can encrypt/decrypt strings between PHP and Android.
Java Part:
import java.security.NoSuchAlgorithmException;
import javax.crypto.Cipher;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
public class MCrypt {
private String iv = "fedcba9876543210";//Dummy iv (CHANGE IT!)
private IvParameterSpec ivspec;
private SecretKeySpec keyspec;
private Cipher cipher;
private String SecretKey = "0123456789abcdef";//Dummy secretKey (CHANGE IT!)
public MCrypt()
{
ivspec = new IvParameterSpec(iv.getBytes());
keyspec = new SecretKeySpec(SecretKey.getBytes(), "AES");
try {
cipher = Cipher.getInstance("AES/CBC/NoPadding");
} catch (NoSuchAlgorithmException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (NoSuchPaddingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public byte[] encrypt(String text) throws Exception
{
if(text == null || text.length() == 0)
throw new Exception("Empty string");
byte[] encrypted = null;
try {
cipher.init(Cipher.ENCRYPT_MODE, keyspec, ivspec);
encrypted = cipher.doFinal(padString(text).getBytes());
} catch (Exception e)
{
throw new Exception("[encrypt] " + e.getMessage());
}
return encrypted;
}
public byte[] decrypt(String code) throws Exception
{
if(code == null || code.length() == 0)
throw new Exception("Empty string");
byte[] decrypted = null;
try {
cipher.init(Cipher.DECRYPT_MODE, keyspec, ivspec);
decrypted = cipher.doFinal(hexToBytes(code));
} catch (Exception e)
{
throw new Exception("[decrypt] " + e.getMessage());
}
return decrypted;
}
public static String bytesToHex(byte[] data)
{
if (data==null)
{
return null;
}
int len = data.length;
String str = "";
for (int i=0; i<len; i++) {
if ((data[i]&0xFF)<16)
str = str + "0" + java.lang.Integer.toHexString(data[i]&0xFF);
else
str = str + java.lang.Integer.toHexString(data[i]&0xFF);
}
return str;
}
public static byte[] hexToBytes(String str) {
if (str==null) {
return null;
} else if (str.length() < 2) {
return null;
} else {
int len = str.length() / 2;
byte[] buffer = new byte[len];
for (int i=0; i<len; i++) {
buffer[i] = (byte) Integer.parseInt(str.substring(i*2,i*2+2),16);
}
return buffer;
}
}
private static String padString(String source)
{
char paddingChar = ' ';
int size = 16;
int x = source.length() % size;
int padLength = size - x;
for (int i = 0; i < padLength; i++)
{
source += paddingChar;
}
return source;
}
}
PHP Part:
<?php
class MCrypt
{
private $iv = 'fedcba9876543210'; #Same as in JAVA
private $key = '0123456789abcdef'; #Same as in JAVA
function __construct()
{
}
function encrypt($str) {
//$key = $this->hex2bin($key);
$iv = $this->iv;
$td = mcrypt_module_open('rijndael-128', '', 'cbc', $iv);
mcrypt_generic_init($td, $this->key, $iv);
$encrypted = mcrypt_generic($td, $str);
mcrypt_generic_deinit($td);
mcrypt_module_close($td);
return bin2hex($encrypted);
}
function decrypt($code) {
//$key = $this->hex2bin($key);
$code = $this->hex2bin($code);
$iv = $this->iv;
$td = mcrypt_module_open('rijndael-128', '', 'cbc', $iv);
mcrypt_generic_init($td, $this->key, $iv);
$decrypted = mdecrypt_generic($td, $code);
mcrypt_generic_deinit($td);
mcrypt_module_close($td);
return utf8_encode(trim($decrypted));
}
protected function hex2bin($hexdata) {
$bindata = '';
for ($i = 0; $i < strlen($hexdata); $i += 2) {
$bindata .= chr(hexdec(substr($hexdata, $i, 2)));
}
return $bindata;
}
}
Usage (Java):
mcrypt = new MCrypt();
/* Encrypt */
String encrypted = MCrypt.bytesToHex( mcrypt.encrypt("Text to Encrypt") );
/* Decrypt */
String decrypted = new String( mcrypt.decrypt( encrypted ) );
Usage (PHP):
$mcrypt = new MCrypt();
#Encrypt
$encrypted = $mcrypt->encrypt("Text to encrypt");
#Decrypt
$decrypted = $mcrypt->decrypt($encrypted);

Java decrypt error: data not block size aligned

I'm trying to encrypt data between my android application and a PHP webservice.
I found the next piece of code in this website: http://schneimi.wordpress.com/2008/11/25/aes-128bit-encryption-between-java-and-php/
But when I try to decrypt I get the Exception of the title "data not block size aligned"
This are the method in my MCrypt class
public String encrypt(String text) throws Exception
{
if(text == null || text.length() == 0)
throw new Exception("Empty string");
Cipher cipher;
byte[] encrypted = null;
try {
cipher = Cipher.getInstance("AES/CBC/NoPadding");
cipher.init(Cipher.ENCRYPT_MODE, keyspec, ivspec);
encrypted = cipher.doFinal(padString(text).getBytes());
} catch (Exception e)
{
throw new Exception("[encrypt] " + e.getMessage());
}
return new String( encrypted );
}
public String decrypt(String code) throws Exception
{
if(code == null || code.length() == 0)
throw new Exception("Empty string");
Cipher cipher;
byte[] decrypted = null;
try {
cipher = Cipher.getInstance("AES/CBC/NoPadding");
cipher.init(Cipher.DECRYPT_MODE, keyspec, ivspec);
decrypted = cipher.doFinal(hexToBytes(code));
} catch (Exception e)
{
throw new Exception("[decrypt] " + e.getMessage());
}
return new String( decrypted );
}
private static byte[] hexToBytes(String hex) {
String HEXINDEX = "0123456789abcdef";
int l = hex.length() / 2;
byte data[] = new byte[l];
int j = 0;
for (int i = 0; i < l; i++) {
char c = hex.charAt(j++);
int n, b;
n = HEXINDEX.indexOf(c);
b = (n & 0xf) << 4;
c = hex.charAt(j++);
n = HEXINDEX.indexOf(c);
b += (n & 0xf);
data[i] = (byte) b;
}
return data;
}
private static String padString(String source)
{
char paddingChar = ' ';
int size = 16;
int x = source.length() % size;
int padLength = size - x;
for (int i = 0; i < padLength; i++)
{
source += paddingChar;
}
return source;
}
And this is how I'm using it in my activity to test:
String encrypted = mcrypt.encrypt(jsonUser.toString());
String decrypted = mcrypt.decrypt(encrypted);
the encrypt method works fine, but the second throws an exception.

At last! I made it work! Thanks for all your suggestion. I would like to share the code just in case somebody get stuck like me:
JAVA
import java.security.NoSuchAlgorithmException;
import javax.crypto.Cipher;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
public class MCrypt {
private String iv = "fedcba9876543210";//Dummy iv (CHANGE IT!)
private IvParameterSpec ivspec;
private SecretKeySpec keyspec;
private Cipher cipher;
private String SecretKey = "0123456789abcdef";//Dummy secretKey (CHANGE IT!)
public MCrypt()
{
ivspec = new IvParameterSpec(iv.getBytes());
keyspec = new SecretKeySpec(SecretKey.getBytes(), "AES");
try {
cipher = Cipher.getInstance("AES/CBC/NoPadding");
} catch (NoSuchAlgorithmException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (NoSuchPaddingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
public byte[] encrypt(String text) throws Exception
{
if(text == null || text.length() == 0)
throw new Exception("Empty string");
byte[] encrypted = null;
try {
cipher.init(Cipher.ENCRYPT_MODE, keyspec, ivspec);
encrypted = cipher.doFinal(padString(text).getBytes());
} catch (Exception e)
{
throw new Exception("[encrypt] " + e.getMessage());
}
return encrypted;
}
public byte[] decrypt(String code) throws Exception
{
if(code == null || code.length() == 0)
throw new Exception("Empty string");
byte[] decrypted = null;
try {
cipher.init(Cipher.DECRYPT_MODE, keyspec, ivspec);
decrypted = cipher.doFinal(hexToBytes(code));
} catch (Exception e)
{
throw new Exception("[decrypt] " + e.getMessage());
}
return decrypted;
}
public static String bytesToHex(byte[] data)
{
if (data==null)
{
return null;
}
int len = data.length;
String str = "";
for (int i=0; i<len; i++) {
if ((data[i]&0xFF)<16)
str = str + "0" + java.lang.Integer.toHexString(data[i]&0xFF);
else
str = str + java.lang.Integer.toHexString(data[i]&0xFF);
}
return str;
}
public static byte[] hexToBytes(String str) {
if (str==null) {
return null;
} else if (str.length() < 2) {
return null;
} else {
int len = str.length() / 2;
byte[] buffer = new byte[len];
for (int i=0; i<len; i++) {
buffer[i] = (byte) Integer.parseInt(str.substring(i*2,i*2+2),16);
}
return buffer;
}
}
private static String padString(String source)
{
char paddingChar = ' ';
int size = 16;
int x = source.length() % size;
int padLength = size - x;
for (int i = 0; i < padLength; i++)
{
source += paddingChar;
}
return source;
}
}
HOW TO USE IT (JAVA)
mcrypt = new MCrypt();
/* Encrypt */
String encrypted = MCrypt.bytesToHex( mcrypt.encrypt("Text to Encrypt") );
/* Decrypt */
String decrypted = new String( mcrypt.decrypt( encrypted ) );
====================================================
PHP
<?php
class MCrypt
{
private $iv = 'fedcba9876543210'; #Same as in JAVA
private $key = '0123456789abcdef'; #Same as in JAVA
function __construct()
{
}
function encrypt($str) {
//$key = $this->hex2bin($key);
$iv = $this->iv;
$td = mcrypt_module_open('rijndael-128', '', 'cbc', $iv);
mcrypt_generic_init($td, $this->key, $iv);
$encrypted = mcrypt_generic($td, $str);
mcrypt_generic_deinit($td);
mcrypt_module_close($td);
return bin2hex($encrypted);
}
function decrypt($code) {
//$key = $this->hex2bin($key);
$code = $this->hex2bin($code);
$iv = $this->iv;
$td = mcrypt_module_open('rijndael-128', '', 'cbc', $iv);
mcrypt_generic_init($td, $this->key, $iv);
$decrypted = mdecrypt_generic($td, $code);
mcrypt_generic_deinit($td);
mcrypt_module_close($td);
return utf8_encode(trim($decrypted));
}
protected function hex2bin($hexdata) {
$bindata = '';
for ($i = 0; $i < strlen($hexdata); $i += 2) {
$bindata .= chr(hexdec(substr($hexdata, $i, 2)));
}
return $bindata;
}
}
HOW TO USE IT (PHP)
<?php
$mcrypt = new MCrypt();
#Encrypt
$encrypted = $mcrypt->encrypt("Text to encrypt");
#Decrypt
$decrypted = $mcrypt->decrypt($encrypted);

I'm guessing your keyspec and ivspec are not valid for decryption. I've typically transformed them into PublicKey and PrivateKey instances and then use the private key to decrypt.

I looked at the comments in the other answer. I ran into a similar problem trying to encrypt a large block of text using open SSL in php (on both sides). I imagine the same issue would come up in Java.
If you have a 1024 bit RSA key, you must split the incoming text into 117 byte chunks (a char is a byte) and encrypt each (you can concatenate them together). On the other end, you must split the encrypted data into 128 byte chunks and decrypt each. This should give you your original message.
Also note that http may not play friendly with the non-ASCII encrypted data. I base64 encode/decode it before and after transmission (plus you have to worry about additional urlencoding for the base64 change, but it is easy).
I'm not sure of your AES key length, but if it's 1024 bits the chunk length is probably the same. If it's not, you will have to divide the bits by 8 to find the byte chunk length coming out. I'm actually not sure how to get it coming in, unfortunately (maybe multiply by 117/128 ?)
Here's some php code:
class Crypto {
public function encrypt($key, $data) {
$crypto = '';
foreach (str_split($data, 117) as $chunk) {
openssl_public_encrypt($chunk, $encrypted, $key);
$crypto .= $encrypted;
}
return $crypto;
}
//Decrypt omitted. Basically the same, change 117 to 128.
/**##+
* Update data for HTTP transmission and retrieval
* Must be used on encrypted data, but also useful for any binary data
* (e.g. zip files).
*/
public function base64_encode($value) {
return rtrim(strtr(base64_encode($value), '+/', '-_'), '=');
}
//String length must be padded for decoding for some reason
public function base64_decode($value) {
return base64_decode(str_pad(strtr($value, '-_', '+/')
, strlen($value) % 4, '=', STR_PAD_RIGHT));
}
/**##-*/
}