为什么AES java解密返回额外的字符？ [英] why AES java decryption return extra characters?
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问题描述
我使用mcrypt我从这里得到它 MCrypt for php和java 。在我的Android应用程序中，我需要php和java安全地通信，所以我得到上面提到的AES。
问题是当php发送加密数据时，java可以解密，但是会包含一些额外的字符。
JAVA代码
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;
私密密码;
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自动生成的catch块
e.printStackTrace（）;
} catch（NoSuchPaddingException e）{
// TODO自动生成的catch块
e.printStackTrace（）;
}
}
public byte [] encrypt（String text）throws异常
{
if（text == null || text.length ）== 0）
抛出新异常（空字符串）;
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（））;
}
返回加密;
}
public byte [] decrypt（String code）throws异常
{
if（code == null || code.length（）== 0）
抛出新的异常（空字符串）;
byte [] decryptpted = null;
try {
cipher.init（Cipher.DECRYPT_MODE，keyspec，ivspec）;
decryptpted = cipher.doFinal（hexToBytes（code））;
} catch（Exception e）
{
throw new Exception（[decrypt]+ e.getMessage（））;
}
返回解密;
}
public static String bytesToHex（byte [] data）
{
if（data == null）
{
return null;
}
int len = data.length;
String str =; （int i = 0; i
str = str +0+ java .lang.Integer.toHexString（数据[1] - 安培;为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]; （int i = 0; i
}
return buffer;
}
}
private static String padString（String source）
{
char paddingChar =''
int size = 16;
int x = source.length（）％size;
int padLength = size - x; （int i = 0; i< padLength; i ++）
{
source + = paddingChar;
}
返回源;
}
}
PHP代码
<？php
class MCrypt
{
private $ iv ='fedcba9876543210'; ＃如JAVA
private $ key ='0123456789abcdef'; ＃如JAVA
函数__construct（）
{
}
函数加密（$ 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）;
返回bin2hex（$ encrypted）;
}
函数解密（$ 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）;
$ decryptpted = mdecrypt_generic（$ td，$ code）;
mcrypt_generic_deinit（$ td）;
mcrypt_module_close（$ td）;
return utf8_encode（trim（$ decryptpted））;
}
保护函数hex2bin（$ hexdata）{
$ bindata =''; （$ i = 0; $ i< strlen（$ hexdata）; $ i + = 2）{
$ bindata。= chr（hexdec（substr（$ hexdata，$ i，2）））;
}
return $ bindata;
}
}
所以场景是java发送数据（简单文本）以JSON格式转换为PHP，php提取数据，对其进行加密，最后以JSON格式回显
PHP调用：
<？php
$ data = json_decode（file_get_contents（'php：// input'），true）;
$ data = $ data [request];
require_onceencryption.php;
$ etool = new MCrypt（）;
$ data = $ etool-> encrypt（$ data）;
$ array = array（'data'=> $ data）;
echo json_encode（$ array）;
JAVA代码：
// sb是StringBuilder
JSONObject j = new JSONObject（sb.toString（））;
加密etool = new encryption（）;
result = j.get（data）。toString（）;
result = new String（etool.decrypt（result））;
Log.d（success remote，result）;
结果是：
example
如果我使用波斯语/阿拉伯语，它会变得更糟糕
like this-> درود
此外，我检查了其他问题，但我无法得到答案。 >
AES加密，在解密文件中得到额外的垃圾字符，而
PHP MCRYPT加密/解密返回隐形奇怪的字符？
提前谢谢！
解决方案
AES 以16个字节的块加密。如果您的输入不是16字节的倍数，则需要填充方案。由于您没有为 Mcrypt 指定任何填充选项，所以使用零填充。
在您的 Java 代码中，您在实例化密码时指定了NoPadding：
cipher = Cipher.getInstance（AES / CBC / NoPadding）;
所以 Java 认为由 php 成为加密数据的一部分。
您只需确保您的 php 和 Java 代码使用相同的填充方案。
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!
解决方案
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.
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