给定Final Block在AES解密时没有正确填充

时间：2015-02-01 13:59:23

标签： java encryption cryptography aes cryptojs

首先，我会说出我的主要目标是什么。我将使用AES加密客户端中的某些内容，然后使用RSA公钥加密重要的AES规范，并将AES加密数据和RSA加密AES规范发送到服务器。因此，在服务器上，我将使用RSA私钥解密AES密钥规范，然后使用这些AES规范，我将解密AES加密数据。我通过测试加密和解密成功地使RSA部分工作。在实施RSa之前，我已经使这个AES艺术工作了。

对于客户端，我使用crypto-js 

<script src="http://crypto-js.googlecode.com/svn/tags/3.1.2/build/rollups/aes.js"></script>
<script src="http://crypto-js.googlecode.com/svn/tags/3.1.2/build/rollups/pbkdf2.js"></script>
<script src="http://crypto-js.googlecode.com/svn/tags/3.1.2/build/components/enc-base64-min.js"></script>
<script type="text/javascript" src="jquery-1.7.1.js"></script>
<script type="text/javascript">

    $("#submit").click(function() {
        var salt = CryptoJS.lib.WordArray.random(16);
        var iv = CryptoJS.lib.WordArray.random(16);
        var pass = CryptoJS.lib.WordArray.random(16);
        var message = "Test Message for encryption";
        var key128Bits = CryptoJS.PBKDF2(pass, salt, { keySize: 128 }); 
        var key128Bits10Iterations = CryptoJS.PBKDF2(pass, salt, { keySize: 128, iterations: 10 });
        var encrypted = CryptoJS.AES.encrypt(message, key128Bits10Iterations, { iv: iv, mode: CryptoJS.mode.CBC, padding: CryptoJS.pad.Pkcs7  });
        var cipherData = encrypted.toString()+":"+salt.toString()+":"+iv.toString()+":"+pass.toString();
        console.log(cipherData);

        $.ajax({
            url: 'encryption',
            type: 'POST',
            data: {
                cipherData: cipherData
            },
            success: function(data) {
                console.log(data);
            },
            failure: function(data) {

            }
        });
    });

</script>

这是我在服务器端使用的代码

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    String encryptedData = request.getParameter("cipherData");
    String data[] = encryptedData.split(":");

    String encrypted = data[0];     
    String salt = data[1];
    String iv = data[2];
    String password = data[3];

    byte[] saltBytes = hexStringToByteArray(salt);
    byte[] ivBytes = hexStringToByteArray(iv);
    IvParameterSpec ivParameterSpec = new IvParameterSpec(ivBytes);        
    SecretKeySpec sKey = null;
    try {
        sKey = (SecretKeySpec) generateKeyFromPassword(password, saltBytes);
    } catch (GeneralSecurityException e) {
        e.printStackTrace();
    }
    try {
        System.out.println( decrypt( encrypted , sKey ,ivParameterSpec));
    } catch (Exception e) {
        e.printStackTrace();
    }
}

public static SecretKey generateKeyFromPassword(String password, byte[] saltBytes) throws GeneralSecurityException {

    KeySpec keySpec = new PBEKeySpec(password.toCharArray(), saltBytes, 10, 128);
    SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
    SecretKey secretKey = keyFactory.generateSecret(keySpec);

    return new SecretKeySpec(secretKey.getEncoded(), "AES");
}

public static byte[] hexStringToByteArray(String s) {

    int len = s.length();
    byte[] data = new byte[len / 2];

    for (int i = 0; i < len; i += 2) {
        data[i / 2] = (byte) ((Character.digit(s.charAt(i), 16) << 4)
                + Character.digit(s.charAt(i+1), 16));
    }

    return data;

}

public static String decrypt(String encryptedData, SecretKeySpec sKey, IvParameterSpec ivParameterSpec) throws Exception { 

    Cipher c = Cipher.getInstance("AES/CBC/PKCS5Padding");
    c.init(Cipher.DECRYPT_MODE, sKey, ivParameterSpec);
    byte[] decordedValue = Base64.decodeBase64(encryptedData);
    byte[] decValue = c.doFinal(decordedValue);
    String decryptedValue = new String(decValue);

    return decryptedValue;
}

首先，我要确保服务器正在接收我发送的相同数据。所以我通过sysout对加密，salt，iv和密码进行了测试。它收到了相同的数据。但是我在第

行得到了例外 
byte[] decValue = c.doFinal(decordedValue);

javax.crypto.BadPaddingException: Given final block not properly padded
at com.sun.crypto.provider.CipherCore.doFinal(CipherCore.java:966)
at com.sun.crypto.provider.CipherCore.doFinal(CipherCore.java:824)
at com.sun.crypto.provider.AESCipher.engineDoFinal(AESCipher.java:436)
at javax.crypto.Cipher.doFinal(Cipher.java:2121)
at com.Encryption.decrypt(Encryption.java:95)
at com.Encryption.doPost(Encryption.java:60)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:644)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:725)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:503)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:136)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:610)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:526)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1078)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:655)
at org.apache.coyote.http11.Http11NioProtocol$Http11ConnectionHandler.process(Http11NioProtocol.java:222)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1566)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1523)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)

你可以看到，在Javascript方面，它是CryptoJS.pad.Pkcs7，在服务器端它是AES / CBC / PKCS5Padding，我已经对它做了一些搜索，发现两者都有是相同的。我既不能将其更改为CryptoJS.pad.Pkcs5，也不能将AES / CBC / PKCS7Padding更改为Crypto-js库和Java内置库。

我也有以下想法。在javascript中，我使用随机盐并传递生成128位密钥。使用相同的salt并传递，我通过定义适当的迭代计数和密钥大小在Java中生成相同的密钥。为什么我必须通过再次生成相同的密钥来延长Java中的进程？我只需将密钥（encrypted.key），encrytedData（encrypted.toString（））和Iv（encrypted.iv）发送到服务器并立即解密数据，而无需再次生成密钥。我是对的吗？我也尝试了这一点，我得到了＃34; AES密钥长度异常无效＆＃34;。为了保持安全性，我将使用RSA公钥对客户端的密钥和Iv进行加密。实现具有非对称性的对称性的原因之一是由于RSA的有限大小的数据被加密。但如果我无法清除BadPaddingException，我就无法实现它。

2 个答案:

答案 0 :(得分：2)

由于您希望使用RSA并且已经实现了它，因此无需使用密码派生。创建随机密钥并随机iv：

var key = CryptoJS.lib.WordArray.random(16); // 128bit
var iv = CryptoJS.lib.WordArray.random(16);  // 128bit
var encrypted = CryptoJS.AES.encrypt(message, key, { iv: iv }); // CBC/PKCS#7 is default

然后将iv.toString(Crypto.enc.Base64)，encrypted.ciphertext.toString(Crypto.enc.Base64)和“RSAencrypt（key）”发送到服务器，解码base64编码的iv和密文，解密RSA密文以获取AES密钥并合并所有这些密钥解密密文。

您的原始问题可能在于您使用的尺寸。 CryptoJS具有内部表示，每个字包含4个字节。这就是你需要除以32以获得128位散列的原因：

var key128Bits = CryptoJS.PBKDF2(pass, salt, { keySize: 128/32 });

另一方面，WordArray仅适用于字节，这就是除以8的原因：

var key = CryptoJS.lib.WordArray.random(128/8);

答案 1 :(得分：2)

感谢Artjom B.

解决方案：工作代码

Javascript /客户端代码 

<script src="http://crypto-js.googlecode.com/svn/tags/3.1.2/build/rollups/aes.js"></script>
<script src="http://crypto-js.googlecode.com/svn/tags/3.1.2/build/rollups/pbkdf2.js"></script>
<script src="http://crypto-js.googlecode.com/svn/tags/3.1.2/build/components/enc-base64-min.js"></script>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.2/jquery.min.js"></script>

<script type="text/javascript">

    $("#submit").click(function() {

        var key = CryptoJS.lib.WordArray.random(16);
        var iv= CryptoJS.lib.WordArray.random(16);
        var message = "<username>user</username>";
        var encrypted = CryptoJS.AES.encrypt(message, key, { iv: iv });

        // If you want the decryption at client side, use the commented code

        /* var decrypted = CryptoJS.AES.decrypt(encrypted, key, { iv:iv });
        function hex2a(hexx) {
            var hex = hexx.toString();//force conversion
            var str = '';
            for (var i = 0; i < hex.length; i += 2)
                str += String.fromCharCode(parseInt(hex.substr(i, 2), 16));
            return str;
        }
        console.log("decrypted: "+hex2a(decrypted)); */

        var cipherData = iv.toString(CryptoJS.enc.Base64)+":"+encrypted.ciphertext.toString()+":"+key.toString(CryptoJS.enc.Base64);

        $.ajax({
            url: 'encryption',
            type: 'POST',
            data: {
                cipherData: cipherData
            },
            success: function(data) {
                console.log(data);
            },
            failure: function(data) {

            }
        });
    });

</script>

服务器/ Java代码 

import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.Key;
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.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

// You have to download and add it into your project, others are Java Inbuilt Libraries
// Do not use sun.misc for Base64 functions
import org.apache.commons.codec.binary.Base64; 

public class BasicDecryption {

//I've done it in post method of servlet

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    String encryptedData = request.getParameter("cipherData");
    String data[] = encryptedData.split(":");
    String iv = data[0];
    byte[] encryptedByteData = hexStringToByteArray(data[1]);
    String keyString = data[2];

    IvParameterSpec iv = new IvParameterSpec(Base64.decodeBase64(iv);
    Key k = new SecretKeySpec(Base64.decodeBase64(keyString),"AES");

    try {
        System.out.println("Decrypted String:"+BasicDecryption.decrypt(Base64.encodeBase64String(encryptedByteData),k,iv));
    } catch (InvalidKeyException | NoSuchAlgorithmException
            | NoSuchPaddingException | IllegalBlockSizeException
            | BadPaddingException | InvalidAlgorithmParameterException e) {
        e.printStackTrace();
    }
}

public static final String decrypt(final String encrypted,final Key key, final IvParameterSpec iv) throws InvalidKeyException,
NoSuchAlgorithmException, NoSuchPaddingException,
IllegalBlockSizeException, BadPaddingException, IOException, InvalidAlgorithmParameterException {

      Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
      cipher.init(Cipher.DECRYPT_MODE, key,iv);
      byte[] raw = Base64.decodeBase64(encrypted);
      byte[] stringBytes = cipher.doFinal(raw);
      String clearText = new String(stringBytes, "UTF8");
      return clearText;
}

public static byte[] hexStringToByteArray(String s) {

    int len = s.length();
    byte[] data = new byte[len / 2];

    for (int i = 0; i < len; i += 2) {
        data[i / 2] = (byte) ((Character.digit(s.charAt(i), 16) << 4)
                + Character.digit(s.charAt(i+1), 16));
    }
    return data;
}
}
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