I was trying to develop an android application that could encrypt and decrypt values. So I have followed this link enter link description here
So far I was able to encrypt a text but I was not able to decrypt it. In my code I have used the same AESHelper class which is mentioned in the link provided.
The below is my activity class that i have used to Encrypt and decrypt the values
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends ActionBarActivity {
EditText text ;
TextView encp,decriptom;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
text = (EditText) findViewById(R.id.editText);
encp = (TextView) findViewById(R.id.valueexcript);
decriptom = (TextView) findViewById(R.id.deexcript);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
public void Ecript(View v)
{
String Key = "avc";
try {
String normalTextEnc = AHShelper.encrypt(Key, text.getText().toString());
Toast.makeText(this,normalTextEnc,Toast.LENGTH_LONG).show();
encp.setText(normalTextEnc);
} catch (Exception e) {
e.printStackTrace();
}
// Toast.makeText(this,"Hello",Toast.LENGTH_LONG).show();
String decript;
try {
decript = AHShelper.decrypt(Key,encp.getText().toString());
decriptom.setText(decript);
Toast.makeText(this,decript,Toast.LENGTH_LONG).show();
} catch (Exception e) {
e.printStackTrace();
}
}
}
AHShelper class that i have used is below
import java.security.SecureRandom;
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
public class AHShelper {
public static String encrypt(String seed, String cleartext)
throws Exception {
byte[] rawKey = getRawKey(seed.getBytes());
byte[] result = encrypt(rawKey, cleartext.getBytes());
return toHex(result);
}
public static String decrypt(String seed, String encrypted)
throws Exception {
byte[] rawKey = getRawKey(seed.getBytes());
byte[] enc = toByte(encrypted);
byte[] result = decrypt(rawKey, enc);
return new String(result);
}
private static byte[] getRawKey(byte[] seed) throws Exception {
KeyGenerator kgen = KeyGenerator.getInstance("AES");
SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");
sr.setSeed(seed);
kgen.init(128, sr); // 192 and 256 bits may not be available
SecretKey skey = kgen.generateKey();
byte[] raw = skey.getEncoded();
return raw;
}
private static byte[] encrypt(byte[] raw, byte[] clear) throws Exception {
SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
byte[] encrypted = cipher.doFinal(clear);
return encrypted;
}
private static byte[] decrypt(byte[] raw, byte[] encrypted)
throws Exception {
SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.DECRYPT_MODE, skeySpec);
byte[] decrypted = cipher.doFinal(encrypted);
return decrypted;
}
public static String toHex(String txt) {
return toHex(txt.getBytes());
}
public static String fromHex(String hex) {
return new String(toByte(hex));
}
public static byte[] toByte(String hexString) {
int len = hexString.length() / 2;
byte[] result = new byte[len];
for (int i = 0; i < len; i++)
result[i] = Integer.valueOf(hexString.substring(2 * i, 2 * i + 2),
16).byteValue();
return result;
}
public static String toHex(byte[] buf) {
if (buf == null)
return "";
StringBuffer result = new StringBuffer(2 * buf.length);
for (int i = 0; i < buf.length; i++) {
appendHex(result, buf[i]);
}
return result.toString();
}
private final static String HEX = "0123456789ABCDEF";
private static void appendHex(StringBuffer sb, byte b) {
sb.append(HEX.charAt((b >> 4) & 0x0f)).append(HEX.charAt(b & 0x0f));
}
}
Basically this code relies on a little trick: if you seed the SHA1PRNG for the SUN provider and Bouncy Castle provider before it is used then it will always generate the same stream of random bytes.
This is not always the case for every provider though; other providers simply mix in the seed. In other words, they may use a pre-seeded PRNG and mix-in the seed instead. In that case the getRawKey method generates different keys for the encrypt and decrypt, which will result in a failure to decrypt.
It could also be the case that a provider decides to use a different algorithm based on SHA-1 altogether, as the algorithm used by SUN/Oracle is not well specified - publicly at least.
Basically this horrible code snippet abuses the SHA1PRNG as a Key Derivation Function or KDF. You should use a true KDF such as PBKDF2 if the input is a password or HKDF if the input is a key. PBKDF2 is build into Java.
That code snippet should be removed. It has been copied from Android snippets, but I cannot find that site anymore. It seems even more dysfunctional then when it was available in other words.
A possible solution to retrieve your data when encrypted with SUN is either to decrypt it on an Oracle provided JDK. Otherwise you could also copy the code of the inner implementation class of the SHA1PRNG and use that to decrypt your data. Note that you do need to keep in mind that the sources of SUN are GPL'ed; you need to adhere to that license if you do. For older Android versions you can use the source code of that. I would strongly advice to remove this horrible piece of code afterwards and rely on PBKDF2 instead.
If you're using an implementation that returns a fully random key then you're completely out of luck. Your data is gone, period. Rest assured that it will be kept confidential to the end of times.
Related
So usually i use one java file to encrypt and decrypt a string to hex with AES,
then my angular app want to consume api, that use the result of it.
this is my old java code
package decryptoor;
import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.util.Formatter;
import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
public class CryptoAndroidKoplak {
private static final String TEXT_ENCODING = "UTF-8";
private static final String CIPHER_TRANSFORMATION = "AES/CBC/PKCS5Padding";
private static final String ENCRYPTION_ALGORITM = "AES";
private static final String TAG = "Crypto";
private Cipher cipher;
private IvParameterSpec initialVector;
// private static void DEBUG(String msg){
// if(IDefines.DEBUG_LOG_TRACE){
// Log.i(TAG, msg);
// }
// }
public CryptoAndroidKoplak() {
try {
cipher = Cipher.getInstance(CIPHER_TRANSFORMATION);
initialVector = new IvParameterSpec(new byte[16]);
} catch (Exception e) {
System.out.println(e.toString());
}
}
public String encryptString(String plainText, String key) throws Exception {
return toHexString(encrypt(plainText, key)).toUpperCase();
}
public byte[] encrypt(String plainText, String key) throws Exception {
byte[] byteKey = getKeyBytes(key);
byte[] plainData = plainText.getBytes(TEXT_ENCODING);
SecretKeySpec keySpec = new SecretKeySpec(byteKey, ENCRYPTION_ALGORITM);
cipher.init(Cipher.ENCRYPT_MODE, keySpec, initialVector);
return cipher.doFinal(plainData);
}
public String decryptString(String encryptedText, String key) throws Exception {
return new String(decrypt(encryptedText, key));
}
public byte[] decrypt(String encryptedText, String key) throws Exception {
byte[] byteKey = getKeyBytes(key);
byte[] encryptData = hexToAscii(encryptedText);
SecretKeySpec keySpec = new SecretKeySpec(byteKey, ENCRYPTION_ALGORITM);
cipher.init(Cipher.DECRYPT_MODE, keySpec, initialVector);
return cipher.doFinal(encryptData);
}
public static String toMD5(String text) throws Exception {
MessageDigest md = MessageDigest.getInstance("MD5");
byte[] data = text.getBytes(TEXT_ENCODING);
return toHexString(md.digest(data));
}
public static String toSHA1(String text) throws Exception {
MessageDigest md = MessageDigest.getInstance("SHA-1");
byte[] data = text.getBytes(TEXT_ENCODING);
return toHexString(md.digest(data));
}
private static String toHexString(byte[] bytes) {
StringBuilder sb = new StringBuilder(bytes.length * 2);
Formatter formatter = new Formatter(sb);
for (byte b : bytes) {
formatter.format("%02x", b);
}
return sb.toString();
}
private static byte[] hexToAscii(String hexStr) {
byte[] buff = new byte[hexStr.length() / 2];
int offset = 0;
for (int i = 0; i < hexStr.length(); i += 2) {
String str = hexStr.substring(i, i + 2);
buff[offset++] = (byte) Integer.parseInt(str, 16);
}
return buff;
}
private static byte[] getKeyBytes(String key) throws UnsupportedEncodingException {
byte[] keyBytes = new byte[16];
byte[] parameterKeyBytes = key.getBytes("UTF-8");
System.arraycopy(parameterKeyBytes, 0, keyBytes, 0, Math.min(parameterKeyBytes.length, keyBytes.length));
return keyBytes;
}
}
and this is my code in angular
import { Injectable } from '#angular/core';
import * as CryptoJS from 'crypto-js';
#Injectable({
providedIn: 'root'
})
export class Encryption {
constructor() {}
encryptAesToString(stringToEncrypt: string, key: string): string {
// first way
// let encrypted;
// try {
// encrypted = CryptoJS.AES.encrypt(JSON.stringify(stringToEncrypt), key);
// } catch (e) {
// console.log(e);
// }
// encrypted = CryptoJS.enc.Hex.stringify(encrypted.ciphertext);
// return encrypted;
// second way
// var b64 = CryptoJS.AES.encrypt(stringToEncrypt, key).toString();
// var e64 = CryptoJS.enc.Base64.parse(b64);
// var eHex = e64.toString(CryptoJS.enc.Hex);
// return eHex;
// third way
const key2 = CryptoJS.enc.Utf8.parse(key);
const iv = CryptoJS.enc.Utf8.parse(key);
const encrypted = CryptoJS.AES.encrypt(stringToEncrypt, key2, {
keySize: 16,
iv: iv,
mode: CryptoJS.mode.ECB,
padding: CryptoJS.pad.Pkcs7,
});
let eHex = CryptoJS.enc.Hex.stringify(encrypted.ciphertext);
return encrypted;
}
decryptAesformString(stringToDecrypt: string, key: string): string {
let decrypted: string = '';
try {
const bytes = CryptoJS.AES.decrypt(stringToDecrypt, key);
if (bytes.toString()) {
decrypted = JSON.parse(bytes.toString(CryptoJS.enc.Utf8));
}
} catch (e) {
console.log(e);
}
return decrypted;
}
}
i have try three code, the first one doesn't return hex, so i try 2 more ways but it doesn't show same encrypted string with the old java code so i cant consume the api.
any idea why this happen?
if you have better way to encrypt and decrypt with key that more simple both in angular and java, it will really help.
many thanks
after give up on how to make it same with my old java code, finally i try to make a new one hehe...
so after i read this answer, then i understand CryptoJS (library that i use in angular) implements the same key derivation function as OpenSSL. so i choose to use basic CryptoJS function to encrypt my string like this
var text = "The quick brown fox jumps over the lazy dog. 👻 👻";
var secret = "René Über";
var encrypted = CryptoJS.AES.encrypt(text, secret);
encrypted = encrypted.toString();
console.log("Cipher text: " + encrypted);
after that, what i need to do is make new java file to encrypt and decrypt aes OpenSsl, and i get what i need here in this answer. i use robert answer, cause accepted answer not really give me what i need.
but like the first answer mentioned, to encrypt and decrypt in this way, we have to install the Java Cryptography Extension (JCE) Unlimited Strength Jurisdiction Policy. Otherwise, AES with key size of 256 won't work and throw an exception:(you won't need JCE with up-to-date java version)
so i add some functionality to force using AES with key size of 256 without to install JCE here. note to use this, actually isnt recomended, please read the comment in ericson answer
then this is my final code to encrypt and decrypt like OpenSsl
package decryptoor;
import groovy.transform.CompileStatic;
import java.io.UnsupportedEncodingException;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.net.URLEncoder;
import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.security.MessageDigest;
import java.security.SecureRandom;
import static java.nio.charset.StandardCharsets.*;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.Permission;
import java.security.PermissionCollection;
import java.util.Arrays;
import java.util.Base64;
import java.util.Map;
import javax.crypto.BadPaddingException;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
/**
* Mimics the OpenSSL AES Cipher options for encrypting and decrypting messages using a shared key (aka password) with symetric ciphers.
*/
#CompileStatic
class OpenSslAes {
/** OpenSSL's magic initial bytes. */
private static final String SALTED_STR = "Salted__";
private static final byte[] SALTED_MAGIC = SALTED_STR.getBytes(US_ASCII);
static String encryptAndURLEncode(String password, String clearText) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, InvalidAlgorithmParameterException, BadPaddingException, UnsupportedEncodingException {
String encrypted = encrypt(password, clearText);
return URLEncoder.encode(encrypted, UTF_8.name() );
}
/**
*
* #param password The password / key to encrypt with.
* #param data The data to encrypt
* #return A base64 encoded string containing the encrypted data.
*/
static String encrypt(String password, String clearText) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, InvalidAlgorithmParameterException, BadPaddingException {
removeCryptographyRestrictions();
final byte[] pass = password.getBytes(US_ASCII);
final byte[] salt = (new SecureRandom()).generateSeed(8);
final byte[] inBytes = clearText.getBytes(UTF_8);
final byte[] passAndSalt = array_concat(pass, salt);
byte[] hash = new byte[0];
byte[] keyAndIv = new byte[0];
for (int i = 0; i < 3 && keyAndIv.length < 48; i++) {
final byte[] hashData = array_concat(hash, passAndSalt);
final MessageDigest md = MessageDigest.getInstance("MD5");
hash = md.digest(hashData);
keyAndIv = array_concat(keyAndIv, hash);
}
final byte[] keyValue = Arrays.copyOfRange(keyAndIv, 0, 32);
final byte[] iv = Arrays.copyOfRange(keyAndIv, 32, 48);
final SecretKeySpec key = new SecretKeySpec(keyValue, "AES");
final Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
cipher.init(Cipher.ENCRYPT_MODE, key, new IvParameterSpec(iv));
byte[] data = cipher.doFinal(inBytes);
data = array_concat(array_concat(SALTED_MAGIC, salt), data);
return Base64.getEncoder().encodeToString( data );
}
/**
* #see http://stackoverflow.com/questions/32508961/java-equivalent-of-an-openssl-aes-cbc-encryption for what looks like a useful answer. The not-yet-commons-ssl also has an implementation
* #param password
* #param source The encrypted data
* #return
*/
static String decrypt(String password, String source) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, InvalidAlgorithmParameterException, IllegalBlockSizeException, BadPaddingException {
removeCryptographyRestrictions();
final byte[] pass = password.getBytes(US_ASCII);
final byte[] inBytes = Base64.getDecoder().decode(source);
final byte[] shouldBeMagic = Arrays.copyOfRange(inBytes, 0, SALTED_MAGIC.length);
if (!Arrays.equals(shouldBeMagic, SALTED_MAGIC)) {
throw new IllegalArgumentException("Initial bytes from input do not match OpenSSL SALTED_MAGIC salt value.");
}
final byte[] salt = Arrays.copyOfRange(inBytes, SALTED_MAGIC.length, SALTED_MAGIC.length + 8);
final byte[] passAndSalt = array_concat(pass, salt);
byte[] hash = new byte[0];
byte[] keyAndIv = new byte[0];
for (int i = 0; i < 3 && keyAndIv.length < 48; i++) {
final byte[] hashData = array_concat(hash, passAndSalt);
final MessageDigest md = MessageDigest.getInstance("MD5");
hash = md.digest(hashData);
keyAndIv = array_concat(keyAndIv, hash);
}
final byte[] keyValue = Arrays.copyOfRange(keyAndIv, 0, 32);
final SecretKeySpec key = new SecretKeySpec(keyValue, "AES");
final byte[] iv = Arrays.copyOfRange(keyAndIv, 32, 48);
final Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
cipher.init(Cipher.DECRYPT_MODE, key, new IvParameterSpec(iv));
final byte[] clear = cipher.doFinal(inBytes, 16, inBytes.length - 16);
return new String(clear, UTF_8);
}
private static byte[] array_concat(final byte[] a, final byte[] b) {
final byte[] c = new byte[a.length + b.length];
System.arraycopy(a, 0, c, 0, a.length);
System.arraycopy(b, 0, c, a.length, b.length);
return c;
}
private static void removeCryptographyRestrictions() {
if (!isRestrictedCryptography()) {
return;
}
try {
/*
* Do the following, but with reflection to bypass access checks:
*
* JceSecurity.isRestricted = false; JceSecurity.defaultPolicy.perms.clear();
* JceSecurity.defaultPolicy.add(CryptoAllPermission.INSTANCE);
*/
final Class<?> jceSecurity = Class.forName("javax.crypto.JceSecurity");
final Class<?> cryptoPermissions = Class.forName("javax.crypto.CryptoPermissions");
final Class<?> cryptoAllPermission = Class.forName("javax.crypto.CryptoAllPermission");
Field isRestrictedField = jceSecurity.getDeclaredField("isRestricted");
isRestrictedField.setAccessible(true);
setFinalStatic(isRestrictedField, true);
isRestrictedField.set(null, false);
final Field defaultPolicyField = jceSecurity.getDeclaredField("defaultPolicy");
defaultPolicyField.setAccessible(true);
final PermissionCollection defaultPolicy = (PermissionCollection) defaultPolicyField.get(null);
final Field perms = cryptoPermissions.getDeclaredField("perms");
perms.setAccessible(true);
((Map<?, ?>) perms.get(defaultPolicy)).clear();
final Field instance = cryptoAllPermission.getDeclaredField("INSTANCE");
instance.setAccessible(true);
defaultPolicy.add((Permission) instance.get(null));
}
catch (final Exception e) {
e.printStackTrace();
}
}
static void setFinalStatic(Field field, Object newValue) throws Exception {
field.setAccessible(true);
Field modifiersField = Field.class.getDeclaredField("modifiers");
modifiersField.setAccessible(true);
modifiersField.setInt(field, field.getModifiers() & ~Modifier.FINAL);
field.set(null, newValue);
}
private static boolean isRestrictedCryptography() {
// This simply matches the Oracle JRE, but not OpenJDK.
return "Java(TM) SE Runtime Environment".equals(System.getProperty("java.runtime.name"));
}
}
I'm writing an app which got a lot of security constraints:
It needs to store files securely encrypted, and must be able to decrypt them. Also, an Operator needs to be able to decrypt the file without the app.
To archive this, I generated a KeyPair on my PC, put the public part in my app, generate an AES SecretKey Key inside the app, encrypt and save it with my public key (for operator purposes), and put the unencrypted key in AndroidKeyStore.
To Encrypt a message, I receive the SecretKey from KeyStore, encrypt my message, get the IV I used as well as the encryptedSecretKey, and write them in a defined order to a byte array (iv->encryptedSecretKey->encryptedMessage).
To Decrypt I try the same in reverse: get the byte array, read the iv and encryptedSecretKey, and pass the rest (encryptedMessage) to my cypher to decrypt.
The problem is, that cipher.doFinal(encryptedMessage) is throwing an
javax.crypto.AEADBadTagExceptionwhich is caused by android.security.KeyStoreException: Signature/MAC verification failed.
I already checked that the encrypted message and the one I want to decrypt are exactly the same. I'm having no idea what I am doing wrong.
The class I use is the following:
package my.company.domain;
import android.content.Context;
import android.content.SharedPreferences;
import android.security.keystore.KeyProperties;
import android.security.keystore.KeyProtection;
import android.support.annotation.NonNull;
import android.util.Base64;
import android.util.Log;
import java.io.DataInputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.charset.StandardCharsets;
import java.security.GeneralSecurityException;
import java.security.InvalidKeyException;
import java.security.KeyFactory;
import java.security.KeyStore;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.PublicKey;
import java.security.SecureRandom;
import java.security.spec.X509EncodedKeySpec;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.spec.GCMParameterSpec;
import javax.crypto.spec.SecretKeySpec;
public class CryptoHelper {
public static final String TAG = CryptoHelper.class.getSimpleName();
private static final String KEY_ALIAS = "OI1lTI1lLI1l0";
private static final char[] KEY_PASSWORD = "Il0VELI1lO".toCharArray();
private static final String PREF_NAME = "CryptoPrefs";
private static final String KEY_ENCRYPTED_SECRET = "encryptedSecret";
private static final String ANDROID_KEY_STORE = "AndroidKeyStore";
private static final int IV_SIZE = 12;
private static final int IV_BIT_LEN = IV_SIZE * 8;
//generate 128 bit key (16), other possible values 192(24), 256(32)
private static final int AES_KEY_SIZE = 16;
private static final String AES = KeyProperties.KEY_ALGORITHM_AES;
private static final String AES_MODE = AES + "/" + KeyProperties.BLOCK_MODE_GCM + "/" + KeyProperties.ENCRYPTION_PADDING_NONE;
private static final String RSA = KeyProperties.KEY_ALGORITHM_RSA;
private static final String RSA_MODE = KeyProperties.KEY_ALGORITHM_RSA + "/" + KeyProperties.BLOCK_MODE_ECB + "/" + KeyProperties.ENCRYPTION_PADDING_NONE;
private static final String RSA_PROVIDER = "AndroidOpenSSL";
private final Context mContext;
private final SharedPreferences mPrefs;
private SecureRandom mSecureRandom;
private KeyStore mAndroidKeyStore;
private PublicKey mPublicKey;
private byte[] mEncryptedSecretKey;
public CryptoHelper(Context context) {
mContext = context;
mSecureRandom = new SecureRandom();
mPrefs = mContext.getSharedPreferences(PREF_NAME, Context.MODE_PRIVATE);
try {
mAndroidKeyStore = KeyStore.getInstance(ANDROID_KEY_STORE);
mAndroidKeyStore.load(null);
} catch (KeyStoreException e) {
Log.wtf(TAG, "Could not get AndroidKeyStore!", e);
} catch (Exception e) {
Log.wtf(TAG, "Could not load AndroidKeyStore!", e);
}
}
public void reset() throws KeyStoreException {
mAndroidKeyStore.deleteEntry(KEY_ALIAS);
}
public byte[] encrypt(byte[] message){
SecretKey secretKey = getSecretKey();
try {
Cipher cipher = Cipher.getInstance(AES_MODE);
cipher.init(Cipher.ENCRYPT_MODE, getSecretKey());
byte[] cryptedBytes = cipher.doFinal(message);
byte[] iv = cipher.getIV();
byte[] encryptedSecretKey = getEncryptedSecretKey();
ByteBuffer buffer = ByteBuffer.allocate(IV_BIT_LEN + encryptedSecretKey.length + cryptedBytes.length);
buffer
.put(iv)
.put(encryptedSecretKey)
.put(cryptedBytes);
return buffer.array();
} catch (GeneralSecurityException e) {
e.printStackTrace();
}
return null;
}
public byte[] encrypt(String message){
return encrypt(message.getBytes(StandardCharsets.UTF_8));
}
public byte[] decrypt(byte[] bytes){
ByteBuffer buffer = ByteBuffer.wrap(bytes);
byte[] iv = new byte[IV_SIZE];
buffer.get(iv);
byte[] unused = getEncryptedSecretKey();
buffer.get(unused);
byte[] encryptedMessage = new byte[bytes.length - IV_SIZE - unused.length];
buffer.get(encryptedMessage);
try {
Cipher cipher = Cipher.getInstance(AES_MODE);
GCMParameterSpec parameterSpec = new GCMParameterSpec(IV_BIT_LEN, iv);
cipher.init(Cipher.DECRYPT_MODE, getSecretKey(), parameterSpec);
byte[] decryptedMessage = cipher.doFinal(encryptedMessage);
return decryptedMessage;
} catch (GeneralSecurityException e) {
e.printStackTrace();
}
return null;
}
public String decryptToString(byte[] bytes){
return new String(decrypt(bytes), StandardCharsets.UTF_8);
}
public byte[] decrypt(FileInputStream fileToDecrypt){
byte[] buffer = null;
try {
buffer = new byte[fileToDecrypt.available()];
fileToDecrypt.read(buffer);
buffer = decrypt(buffer);
} catch (IOException e) {
e.printStackTrace();
}
return buffer;
}
public PublicKey getPublicKey() {
if (null == mPublicKey) {
mPublicKey = readPublicKey();
}
return mPublicKey;
}
public byte[] getEncryptedSecretKey() {
if (null == mEncryptedSecretKey){
mEncryptedSecretKey = Base64.decode(mPrefs.getString(KEY_ENCRYPTED_SECRET, null), Base64.NO_WRAP);
}
return mEncryptedSecretKey;
}
private void saveEncryptedSecretKey(byte[] encryptedSecretKey){
String base64EncryptedKey = Base64.encodeToString(encryptedSecretKey, Base64.NO_WRAP);
mPrefs.edit().putString(KEY_ENCRYPTED_SECRET, base64EncryptedKey).apply();
}
protected SecretKey getSecretKey(){
SecretKey secretKey = null;
try {
if (!mAndroidKeyStore.containsAlias(KEY_ALIAS)){
generateAndStoreSecureKey();
}
secretKey = (SecretKey) mAndroidKeyStore.getKey(KEY_ALIAS, KEY_PASSWORD);
} catch (KeyStoreException e) {
Log.wtf(TAG, "Could not check AndroidKeyStore alias!", e);
secretKey = null;
} catch (GeneralSecurityException e) {
e.printStackTrace();
secretKey = null;
}
return secretKey;
}
private void generateAndStoreSecureKey()
throws NoSuchPaddingException, NoSuchAlgorithmException, NoSuchProviderException, InvalidKeyException, KeyStoreException, BadPaddingException, IllegalBlockSizeException {
SecretKey secretKey = generateSecureRandomKey();
PublicKey publicKey = getPublicKey();
Cipher keyCipher = Cipher.getInstance(RSA_MODE, RSA_PROVIDER);
keyCipher.init(Cipher.ENCRYPT_MODE, publicKey);
byte[] encryptedSecretKeyBytes = keyCipher.doFinal(secretKey.getEncoded());
saveEncryptedSecretKey(encryptedSecretKeyBytes);
KeyProtection keyProtection = new KeyProtection.Builder(KeyProperties.PURPOSE_DECRYPT | KeyProperties.PURPOSE_ENCRYPT | KeyProperties.PURPOSE_VERIFY)
.setBlockModes(KeyProperties.BLOCK_MODE_GCM)
.setEncryptionPaddings(KeyProperties.ENCRYPTION_PADDING_NONE)
.build();
mAndroidKeyStore.setEntry(KEY_ALIAS, new KeyStore.SecretKeyEntry(secretKey), keyProtection);
}
protected PublicKey readPublicKey() {
DataInputStream dis = null;
PublicKey key = null;
try {
dis = new DataInputStream(mContext.getResources().getAssets().open("public_key.der"));
byte[] keyBytes = new byte[dis.available()];
dis.readFully(keyBytes);
X509EncodedKeySpec spec = new X509EncodedKeySpec(keyBytes);
KeyFactory facotory = KeyFactory.getInstance(RSA);
key = facotory.generatePublic(spec);
} catch (Exception e) {
key = null;
} finally {
if (null != dis) {
try {
dis.close();
} catch (IOException e) {
Log.wtf(TAG, "Cannot Close Stream!", e);
}
}
}
return key;
}
#NonNull
protected SecretKey generateSecureRandomKey() {
return new SecretKeySpec(generateSecureRandomBytes(AES_KEY_SIZE), AES);
}
#NonNull
protected byte[] generateSecureRandomBytes(int byteCount) {
byte[] keyBytes = new byte[byteCount];
mSecureRandom.nextBytes(keyBytes);
return keyBytes;
}
}
And I Test it like this:
#Test
public void testCrypto() throws Exception {
CryptoHelper crypto = new CryptoHelper(InstrumentationRegistry.getTargetContext());
crypto.reset();
String verySecretOpinion = "we're all doomed";
byte[] encrypt = crypto.encrypt(verySecretOpinion);
Assert.assertNotNull("Encrypted secret is Null!", encrypt);
Assert.assertFalse("encrypted Bytes are the same as Input!", new String(encrypt, StandardCharsets.UTF_8).equals(verySecretOpinion));
String decryptedString = crypto.decryptToString(encrypt);
Assert.assertNotNull("Decrypted String must be Non-Null!", decryptedString);
Assert.assertEquals("Decrypted String doesn't equal encryption input!", verySecretOpinion, decryptedString);
}
By the way minSdkVersion is 25, so higher than Marshmallow
UPDATE:
Fixed Cipher.DECRYPT_MODE to ENCRYPT_MODE on saving the SecretKey thx to James K Polk's comment
it works If I switch from BlockMode GCM to BlockMode CBC (and changing the GCMParameterSpec to IvParamterSpec but loose the verification of the GCM Mode.
There are at least two problems with the Operator interface. First, you RSA encrypt the secret key using the wrong Cipher mode: you used DECRYPT mode when you should have used encrypt. Secondly, you are using RSA without any padding. You need to use a real padding mode, one of the OEAP padding modes is recommended.
An error in the encryption side occurs when sizing the buffer used to hold the result:
ByteBuffer buffer = ByteBuffer.allocate(IV_BIT_LEN + encryptedSecretKey.length + cryptedBytes.length);
allocates too much space. IV_BIT_LEN should probably be changed to IV_SIZE to get the correctly sized ByteBuffer.
The last mistake is the failure to account for the GCM authentication tag length when setting the GCMParameterSpec on the decrypt side. You initialized the tag length in this line
GCMParameterSpec parameterSpec = new GCMParameterSpec(IV_BIT_LEN, iv);
but that's incorrect, the tag length is unrelated to the IV. Since you did not explicitly set the GCMParameterSpec on the encrypt side you got the default tag length, which happens to be 128.
You can retrieve the tag length on the encrypt side by calling
cipher.getParameters().getParameterSpec(GCMParameterSpec.class) to get the parameter spec. From this you can retrieve both the tag length and the iv. You should probably consider the tag length, 16 bytes = 128 bits, to be a hard-coded constant and not transmit it. The receiver should similar assume the tag length is 128 bits.
I am trying Encryption/Decryption in android using code provided
here:
http://iamvijayakumar.blogspot.com/2013/10/android-example-for-encrypt-and-decrypt.html
The code is working for my device which runs android 4.1 but does not seem to run in an android 5.0.1 device
The error Log is provided below.
AESHelper Class:
package com.myapplication;
import javax.crypto.KeyGenerator;
import java.security.SecureRandom;
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
public class AESHelper {
public static String encrypt(String seed, String cleartext) throws Exception {
byte[] rawKey = getRawKey(seed.getBytes());
byte[] result = encrypt(rawKey, cleartext.getBytes());
return toHex(result);
}
public static String decrypt(String seed, String encrypted) throws Exception {
byte[] rawKey = getRawKey(seed.getBytes());
byte[] enc = toByte(encrypted);
byte[] result = decrypt(rawKey, enc);
return new String(result);
}
private static byte[] getRawKey(byte[] seed) throws Exception {
KeyGenerator kgen = KeyGenerator.getInstance("AES");
SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");
sr.setSeed(seed);
kgen.init(128, sr); // 192 and 256 bits may not be available
SecretKey skey = kgen.generateKey();
byte[] raw = skey.getEncoded();
return raw;
}
private static byte[] encrypt(byte[] raw, byte[] clear) throws Exception {
SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
byte[] encrypted = cipher.doFinal(clear);
return encrypted;
}
private static byte[] decrypt(byte[] raw, byte[] encrypted) throws Exception {
SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.DECRYPT_MODE, skeySpec);
byte[] decrypted = cipher.doFinal(encrypted);
return decrypted;
}
public static String toHex(String txt) {
return toHex(txt.getBytes());
}
public static String fromHex(String hex) {
return new String(toByte(hex));
}
public static byte[] toByte(String hexString) {
int len = hexString.length()/2;
byte[] result = new byte[len];
for (int i = 0; i < len; i++)
result[i] = Integer.valueOf(hexString.substring(2*i, 2*i+2), 16).byteValue();
return result;
}
public static String toHex(byte[] buf) {
if (buf == null)
return "";
StringBuffer result = new StringBuffer(2*buf.length);
for (int i = 0; i < buf.length; i++) {
appendHex(result, buf[i]);
}
return result.toString();
}
private final static String HEX = "0123456789ABCDEF";
private static void appendHex(StringBuffer sb, byte b) {
sb.append(HEX.charAt((b>>4)&0x0f)).append(HEX.charAt(b&0x0f));
}
}
MainActivity Calss:
package com.myapplication;
import android.os.Bundle;
import android.app.Activity;
import android.util.Log;
import android.view.Menu;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends Activity {
String seedValue = "This Is MySecure";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
String normalText = "ABCD";
String normalTextEnc;
try {
normalTextEnc = AESHelper.encrypt(seedValue, normalText);
String normalTextDec = AESHelper.decrypt(seedValue, normalTextEnc);
TextView txe = new TextView(this);
txe.setTextSize(14);
txe.setText("Normal Text ::"+normalText +" \n Encrypted Value :: "+normalTextEnc +" \n Decrypted value :: "+normalTextDec);
setContentView(txe);
} catch (Exception e) {
// TODO Auto-generated catch block
Log.e("MYAPP", "exception", e);
}
}
Log:
07-02 21:06:45.545 11608-11608/com.myapplication E/MYAPP: exception
javax.crypto.BadPaddingException: pad block corrupted
at com.android.org.bouncycastle.jcajce.provider.symmetric.util.BaseBlockCipher.engineDoFinal(BaseBlockCipher.java:854)
at javax.crypto.Cipher.doFinal(Cipher.java:1340)
at com.dhungana.aditya.myapplication.AESHelper.decrypt(AESHelper.java:54)
at com.dhungana.aditya.myapplication.AESHelper.decrypt(AESHelper.java:27)
at com.dhungana.aditya.myapplication.MainActivity.onCreate(MainActivity.java:27)
at android.app.Activity.performCreate(Activity.java:5933)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2269)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2376)
at android.app.ActivityThread.access$800(ActivityThread.java:147)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1281)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5253)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:948)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:743)
You probably need to declare a padding algorithm if your input is not a exact multiple of the key length.
Try to instantiate the cipher with "AES/CBC/PKCS5Padding"
The code bellow takes a String and encrypts it using AES/CBC/PKCS5PADDING as transformation. I am learning as I go and I have a few questions about my code.
1. Is SecureRandom ok for generating my KEY and my IV ?
2. Whats up with all these exceptions?
4. Is my code creating any vulnerabilities in the encryption process? (mistakes maybe?)
3. Am I seeding SEcureRandom Properly?
I'm hopping to incorporate this into a larger project or build on this. Any suggestions for making the code easier to work with multiple classes?
import java.io.UnsupportedEncodingException;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.KeyGenerator;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.spec.IvParameterSpec;
public class AESCrypt {
private SecureRandom r = new SecureRandom();
private Cipher c;
private IvParameterSpec IV;
private SecretKey s_KEY;
// Constructor
public AESCrypt() throws NoSuchAlgorithmException, NoSuchPaddingException {
this.c = Cipher.getInstance("AES/CBC/PKCS5PADDING");
this.IV = generateIV();
this.s_KEY = generateKEY();
}
// COnvert the String to bytes..Should I be using UTF-8? I dont think it
// messes with the encryption and this way any pc can read it ?
// Initialize the cipher
// Encrypt the String of bytes
// Return encrypted bytes
protected byte[] encrypt(String strToEncrypt) throws InvalidKeyException,
InvalidAlgorithmParameterException, IllegalBlockSizeException,
BadPaddingException, UnsupportedEncodingException {
byte[] byteToEncrypt = strToEncrypt.getBytes("UTF-8");
this.c.init(Cipher.ENCRYPT_MODE, this.s_KEY, this.IV, this.r);
byte[] encryptedBytes = this.c.doFinal(byteToEncrypt);
return encryptedBytes;
}
// Initialize the cipher in DECRYPT_MODE
// Decrypt and store as byte[]
// Convert to plainText and return
protected String decrypt(byte[] byteToDecrypt) throws InvalidKeyException,
InvalidAlgorithmParameterException, IllegalBlockSizeException,
BadPaddingException {
this.c.init(Cipher.DECRYPT_MODE, this.s_KEY, this.IV);
byte[] plainByte = this.c.doFinal(byteToDecrypt);
String plainText = new String(plainByte);
return plainText;
}
// Create the IV.
// Create a Secure Random Number Generator and an empty 16byte array. Fill
// the array.
// Returns IV
private IvParameterSpec generateIV() {
byte[] newSeed = r.generateSeed(16);
r.setSeed(newSeed);
byte[] byteIV = new byte[16];
r.nextBytes(byteIV);
IV = new IvParameterSpec(byteIV);
return IV;
}
// Create a "KeyGenerator" that takes in 'AES' as parameter
// Create a "SecureRandom" Object and use it to initialize the
// "KeyGenerator"
// keyGen.init(256, sRandom); Initialize KeyGenerator with parameters
// 256bits AES
private SecretKey generateKEY() throws NoSuchAlgorithmException {
// byte[] bytKey = AES_KEY.getBytes(); // Converts the Cipher Key to
// Byte format
// Should I use SHA-2 to get a random key or is this better?
byte[] newSeed = r.generateSeed(32);
r.setSeed(newSeed);
KeyGenerator keyGen = KeyGenerator.getInstance("AES"); // A
// "KEyGenerator"
// object,
SecureRandom sRandom = r.getInstanceStrong(); // A "SecureRandom" object
// used to init the
// keyGenerator
keyGen.init(256, sRandom); // Initialize RAndom Number Generator
s_KEY = keyGen.generateKey();
return s_KEY;
}
public String byteArrayToString(byte[] s) {
String string = new String(s);
return string;
}
// Get Methods for all class variables
public Cipher getCipher() {
return c;
}
public IvParameterSpec getIV() {
return IV;
}
public SecretKey getSecretKey() {
return s_KEY;
}
}
Thanks to everyone who responds!
I have an app which encrypts some text strings, and then writes these to a file.
The desktop version of the app is reading the file and decrypts the data. The problem is that whenever I decrypt on the desktop version , I get a "javax.crypto.BadPaddingException: Given final block not properly padded"
Both the app and the desktop are using the same code:
import java.security.SecureRandom;
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
public class SSL {
private final static String HEX = "0123456789ABCDEF";
public static String encrypt(Session current, String cleartext) throws Exception {
byte[] rawKey = getRawKey(current.getCurrentSession().getBytes());
byte[] result = encrypt(rawKey, cleartext.getBytes());
return toHex(result);
}
public static String decrypt(Session current, String encrypted) throws Exception {
byte[] rawKey = getRawKey(current.getCurrentSession().getBytes());
byte[] enc = toByte(encrypted);
byte[] result = decrypt(rawKey, enc);
return new String(result);
}
private static byte[] getRawKey(byte[] seed) throws Exception {
KeyGenerator kgen = KeyGenerator.getInstance("AES");
SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");
sr.setSeed(seed);
kgen.init(128, sr); // 192 and 256 bits may not be available
SecretKey skey = kgen.generateKey();
byte[] raw = skey.getEncoded();
return raw;
}
private static byte[] encrypt(byte[] raw, byte[] clear) throws Exception {
SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
byte[] encrypted = cipher.doFinal(clear);
return encrypted;
}
private static byte[] decrypt(byte[] raw, byte[] encrypted) throws Exception {
SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.DECRYPT_MODE, skeySpec);
byte[] decrypted = cipher.doFinal(encrypted);
return decrypted;
}
public static String toHex(String txt) {
return toHex(txt.getBytes());
}
public static String fromHex(String hex) {
return new String(toByte(hex));
}
public static byte[] toByte(String hexString) {
int len = hexString.length()/2;
byte[] result = new byte[len];
for (int i = 0; i < len; i++)
result[i] = Integer.valueOf(hexString.substring(2*i, 2*i+2), 16).byteValue();
return result;
}
public static String toHex(byte[] buf) {
if (buf == null)
return "";
StringBuffer result = new StringBuffer(2*buf.length);
for (int i = 0; i < buf.length; i++) {
appendHex(result, buf[i]);
}
return result.toString();
}
private static void appendHex(StringBuffer sb, byte b) {
sb.append(HEX.charAt((b>>4)&0x0f)).append(HEX.charAt(b&0x0f));
}
}
Why can't I decrypt the data on the desktop version? Are the crypto implementations in Android SDK and java 1.7 different?
Note: If I decrypt the encrypted android data on the android, it works. If I encrypt and decrypt on the desktop, it also works. The problem seems to be somewhere between those two.
I have finally found the whole solution.
There were some major issues, and I would like to explain them here so that more users can find the answer. Firstly, the two things pointed out by Duncan needed to be fixed.
After fixing these issues I still had the same problem, and found out that using a pseudo random number to create the raw key is done differently by different platforms/OS'. If you want to have crossplatform independencies, don't use SHA1PRNG as your key algorithm. Instead, use PBEWithSHA256And256BitAES-CBC-BC. I am using the implementation from BouncyCastle, see below for full crypto code.
import java.io.UnsupportedEncodingException;
import java.security.Security;
import java.security.spec.KeySpec;
import java.util.Random;
import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.SecretKeySpec;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
public class SSL {
private final static String HEX = "0123456789ABCDEF";
private final static String ENC = "US-ASCII";
private final static int ITERATION = 1337;
private static final String RANDOM_ALGORITHM = "PBEWithSHA256And256BitAES-CBC-BC";
private static final String CIPHER_ALGORITHM = "AES/CBC/PKCS5Padding";
private static final String SECRET_KEY_ALGORITHM = "AES";
private static IvParameterSpec ips;
public static void init(byte[] iv) {
if(iv == null) {
iv = new byte[16];
Random random = new Random();
random.nextBytes(iv);
}
ips = new IvParameterSpec(iv);
Security.addProvider(new BouncyCastleProvider());
}
public static byte[] getCertificate() {
return ips.getIV();
}
public static String encrypt(Session current, String cleartext) throws Exception {
byte[] rawKey = getRawKey(current.getCurrentSession().toCharArray());
byte[] result = encrypt(rawKey, cleartext.getBytes(ENC));
return toHex(result);
}
public static String decrypt(Session current, String encrypted) throws Exception {
byte[] rawKey = getRawKey(current.getCurrentSession().toCharArray());
byte[] enc = toByte(encrypted);
byte[] result = decrypt(rawKey, enc);
return new String(result, ENC);
}
private static byte[] getRawKey(char[] seed) throws Exception {
KeySpec keySpec = new PBEKeySpec(seed, ips.getIV(), ITERATION);
SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(RANDOM_ALGORITHM);
byte[] keyBytes = keyFactory.generateSecret(keySpec).getEncoded();
SecretKey secretKey = new SecretKeySpec(keyBytes, "AES");
return secretKey.getEncoded();
}
private static byte[] encrypt(byte[] raw, byte[] clear) throws Exception {
SecretKeySpec skeySpec = new SecretKeySpec(raw, SECRET_KEY_ALGORITHM);
Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM);
cipher.init(Cipher.ENCRYPT_MODE, skeySpec, ips);
byte[] encrypted = cipher.doFinal(clear);
return encrypted;
}
private static byte[] decrypt(byte[] raw, byte[] encrypted) throws Exception {
SecretKeySpec skeySpec = new SecretKeySpec(raw, SECRET_KEY_ALGORITHM);
Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM);
cipher.init(Cipher.DECRYPT_MODE, skeySpec, ips);
byte[] decrypted = cipher.doFinal(encrypted);
return decrypted;
}
public static String toHex(String txt) throws UnsupportedEncodingException {
return toHex(txt.getBytes(ENC));
}
public static String fromHex(String hex) throws UnsupportedEncodingException {
return new String(toByte(hex), ENC);
}
public static byte[] toByte(String hexString) {
int len = hexString.length()/2;
byte[] result = new byte[len];
for (int i = 0; i < len; i++)
result[i] = Integer.valueOf(hexString.substring(2*i, 2*i+2), 16).byteValue();
return result;
}
public static String toHex(byte[] buf) {
if (buf == null)
return "";
StringBuffer result = new StringBuffer(2*buf.length);
for (int i = 0; i < buf.length; i++) {
appendHex(result, buf[i]);
}
return result.toString();
}
private static void appendHex(StringBuffer sb, byte b) {
sb.append(HEX.charAt((b>>4)&0x0f)).append(HEX.charAt(b&0x0f));
}
}
There are at least two problems with your code that will affect its functionality on different platforms:
You must specify a character set when calling getBytes() or new String(...). Without this, the results will be different if your platforms have different default charsets.
You must fully specify your encryption algorithm, e.g. replace "AES" with "AES/CBC/PKCS5Padding" to avoid differences between providers.