Question

我正在尝试从服务器解密加密的字符串。但是当我解密它时，我会遇到以下错误。我需要成功解密字符串。我们使用 AES 256 cbc

> java.lang.Exception: [decrypt] error:1e06b065:Cipher
> functions:EVP_DecryptFinal_ex:BAD_DECRYPT
11-18 12:32:12.976 14325-14325/aes.example.com.aes_encyrption_demo W/art: Before Android 4.1, method android.graphics.PorterDuffColorFilter android.support.graphics.drawable.VectorDrawableCompat.updateTintFilter(android.graphics.PorterDuffColorFilter, android.content.res.ColorStateList, android.graphics.PorterDuff$Mode) would have incorrectly overridden the package-private method in android.graphics.drawable.Drawable
11-18 12:32:13.069 14325-14325/aes.example.com.aes_encyrption_demo W/System.err: java.lang.Exception: [decrypt] error:1e06b065:Cipher functions:EVP_DecryptFinal_ex:BAD_DECRYPT
11-18 12:32:13.069 14325-14325/aes.example.com.aes_encyrption_demo W/System.err:     at aes.example.com.aes_encyrption_demo.MCrypt.decrypt(MCrypt.java:73)
11-18 12:32:13.069 14325-14325/aes.example.com.aes_encyrption_demo W/System.err:     at aes.example.com.aes_encyrption_demo.MainActivity.onCreate(MainActivity.java:59)
11-18 12:32:13.069 14325-14325/aes.example.com.aes_encyrption_demo W/System.err:     at android.app.Activity.performCreate(Activity.java:6303)
11-18 12:32:13.069 14325-14325/aes.example.com.aes_encyrption_demo W/System.err:     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1108)
11-18 12:32:13.069 14325-14325/aes.example.com.aes_encyrption_demo W/System.err:     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2376)
11-18 12:32:13.069 14325-14325/aes.example.com.aes_encyrption_demo W/System.err:     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2483)
11-18 12:32:13.069 14325-14325/aes.example.com.aes_encyrption_demo W/System.err:     at android.app.ActivityThread.access$900(ActivityThread.java:153)
11-18 12:32:13.069 14325-14325/aes.example.com.aes_encyrption_demo W/System.err:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1349)
11-18 12:32:13.069 14325-14325/aes.example.com.aes_encyrption_demo W/System.err:     at android.os.Handler.dispatchMessage(Handler.java:102)
11-18 12:32:13.069 14325-14325/aes.example.com.aes_encyrption_demo W/System.err:     at android.os.Looper.loop(Looper.java:148)
11-18 12:32:13.069 14325-14325/aes.example.com.aes_encyrption_demo W/System.err:     at android.app.ActivityThread.main(ActivityThread.java:5442)
11-18 12:32:13.069 14325-14325/aes.example.com.aes_encyrption_demo W/System.err:     at java.lang.reflect.Method.invoke(Native Method)
11-18 12:32:13.069 14325-14325/aes.example.com.aes_encyrption_demo W/System.err:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:738)
11-18 12:32:13.069 14325-14325/aes.example.com.aes_encyrption_demo W/System.err:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:628)

当我使用AES / CBC / NoPadding时，我能够解密，但文本是附上垃圾字符。

解密 a：2：{s：5：“email”; s：24：“afroj.alam@broc.com”; s：8：“密码”; s：7： “Test123”;}

实际字符串 一：2：{S：5： “电子邮件”; S：24： “afroj.alam@broc.com”; S：8： “密码”; S：7： “Test123”;}

案例1：AES / CBC / PKCS5Padding：BAD_DECRYPT或BAD PADDING错误

案例2：AES / CBC / NoPadding：解密文本末尾的垃圾值

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");
//            cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
        } 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;
    }

Activity.java

try{
         decrypted = new String( mcrypt.decrypt( msg ) );
        }catch (Exception e){
            e.printStackTrace();
        }
        System.out.println("decrypted: " + decrypted);

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;
        }

}

我已经在stackoverflow上尝试了很多链接。

参考： http://www.androidsnippets.com/encrypt-decrypt-between-android-and-php.html

修改

当我使用AES / CBC / PKCS5Padding时，解密失败并出现错误，这是因为服务器php代码没有正确应用填充，还是在我的结尾？如何解决这个问题。

编辑2

发现问题我尝试使用16字节密钥，但是得到了一个错误的填充异常，这是因为服务器端代码没有实现PKCS7。在服务器端实施PKCS7填充后，问题得以解决。如果未在加密字符串中添加填充，AES / CBC / PKCS5Padding模式将提供错误的填充异常。

Answer 1

PHP使用非确定性零填充，只需从解密的字节数组中删除所有零值字节即可将其删除。当然，这也将从明文中删除任何零字节值。

注意：

您的密钥大小为256位时使用AES-256。目前它不是，它将包含128位，因此可能使用AES-128;
您目前正在使用Java中字符串的平台编码和以及 PHP中字符串的某种编码，您应确保编码匹配（从不使用new String(byte[])或getBytes()未明确指定编码;;
键由随机字节组成，而不是字符;
CBC不应用于传输模式加密。

使用SSL / TLS INSTEAD

Answer 2

当我尝试使用16字节密钥时发现问题。我得到了一个错误的填充异常，这是因为服务器端代码没有实现PKCS7。

当我使用AES / CBC / NoPadding模式时，没有错误，但解密的字符串在末尾包含垃圾值。这是因为填充没有添加到加密字符串中。

在服务器端实施PKCS7填充后，问题得以解决。如果未在加密字符串中添加填充，AES / CBC / PKCS5Padding模式将提供错误的填充异常。

请参阅https://gist.github.com/Halama/5956871以在加密时在php中实现填充。

密码破解java

2 个答案: