Java "Given final block not properly padded" Exception in Tomcat5.5 Server

Question

I'm having problem with decoding an encrypted text.
When the encrypted message is received, Java would sometimes throw an exception below.

javax.crypto.BadPaddingException: Given final block not properly padded
    at com.sun.crypto.provider.SunJCE_h.b(DashoA12275)
    at com.sun.crypto.provider.SunJCE_h.b(DashoA12275)
    at com.sun.crypto.provider.SunJCE_af.b(DashoA12275)
    at com.sun.crypto.provider.PBEWithMD5AndDESCipher.engineDoFinal(DashoA12275)
    at javax.crypto.Cipher.doFinal(DashoA12275)
    at com.inv.my.encrypt.StringEncrypter.decrypt(StringEncrypter.java:206)
    at com.inv.my.encrypt.EncryptDecryptMachine.decrypt(EncryptDecryptMachine.java:56)
    at com.inv.my.servlet.transfer.hq.RequestStockQty.doPost(RequestStockQty.java:47)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:709)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:592)
    at org.apache.catalina.security.SecurityUtil$1.run(SecurityUtil.java:244)
    at java.security.AccessController.doPrivileged(Native Method)
    at javax.security.auth.Subject.doAsPrivileged(Subject.java:517)
    at org.apache.catalina.security.SecurityUtil.execute(SecurityUtil.java:276)
    at org.apache.catalina.security.SecurityUtil.doAsPrivilege(SecurityUtil.java:162)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:262)
    at org.apache.catalina.core.ApplicationFilterChain.access$0(ApplicationFilterChain.java:192)
    at org.apache.catalina.core.ApplicationFilterChain$1.run(ApplicationFilterChain.java:171)
    at java.security.AccessController.doPrivileged(Native Method)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:167)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:172)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:151)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:874)
    at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665)
    at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528)
    at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81)
    at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:689)
    at java.lang.Thread.run(Thread.java:595)

My server setup is...

Ubuntu 8.04 LTS
Java 5
Tomcat5.5

Weirdly enough the problem is intermittent. After restarting the server, it would go away but would come back later again which I would restart my tomcat again just to temporarily fix it.

Thanks!

Edit-Add Code:

The code I use is from...

http://www.idevelopment.info/data/Programming/java/security/java_cryptography_extension/StringEncrypter.java

and modified it a bit, below is my actual code. I removed the comments to make it shorter.

Thanks!

public class StringEncrypter {
Cipher ecipher;
Cipher dcipher;


public StringEncrypter(SecretKey key, String algorithm) {
    try {
        ecipher = Cipher.getInstance(algorithm);
        dcipher = Cipher.getInstance(algorithm);
        ecipher.init(Cipher.ENCRYPT_MODE, key);
        dcipher.init(Cipher.DECRYPT_MODE, key);
    } catch (NoSuchPaddingException e) {
        System.out.println("EXCEPTION: NoSuchPaddingException");
    } catch (NoSuchAlgorithmException e) {
        System.out.println("EXCEPTION: NoSuchAlgorithmException");
    } catch (InvalidKeyException e) {
        System.out.println("EXCEPTION: InvalidKeyException");
    }
}



public StringEncrypter(String passPhrase) {

    setPassPhrase( passPhrase );

}


public void setPassPhrase( String passPhrase ) {

    // 8-bytes Salt
    byte[] salt = {
        (byte)0xA9, (byte)0x9B, (byte)0xC8, (byte)0x32,
        (byte)0x56, (byte)0x34, (byte)0xE3, (byte)0x03
    };

    // Iteration count
    int iterationCount = 19;

    try {

        KeySpec keySpec = new PBEKeySpec(passPhrase.toCharArray(), salt, iterationCount);
        SecretKey key = SecretKeyFactory.getInstance("PBEWithMD5AndDES").generateSecret(keySpec);

        ecipher = Cipher.getInstance(key.getAlgorithm());
        dcipher = Cipher.getInstance(key.getAlgorithm());

        // Prepare the parameters to the cipthers
        AlgorithmParameterSpec paramSpec = new PBEParameterSpec(salt, iterationCount);

        ecipher.init(Cipher.ENCRYPT_MODE, key, paramSpec);
        dcipher.init(Cipher.DECRYPT_MODE, key, paramSpec);

    } catch (InvalidAlgorithmParameterException e) {
        System.out.println("EXCEPTION: InvalidAlgorithmParameterException");
    } catch (InvalidKeySpecException e) {
        System.out.println("EXCEPTION: InvalidKeySpecException");
    } catch (NoSuchPaddingException e) {
        System.out.println("EXCEPTION: NoSuchPaddingException");
    } catch (NoSuchAlgorithmException e) {
        System.out.println("EXCEPTION: NoSuchAlgorithmException");
    } catch (InvalidKeyException e) {
        System.out.println("EXCEPTION: InvalidKeyException");
    }
}


public String encrypt(String str) {
    try {
        // Encode the string into bytes using utf-8
        byte[] utf8 = str.getBytes("UTF8");

        // Encrypt
        byte[] enc = ecipher.doFinal(utf8);

        // Encode bytes to base64 to get a string
        return new sun.misc.BASE64Encoder().encode(enc);

    } catch (BadPaddingException e) {
        e.printStackTrace();
    } catch (IllegalBlockSizeException e) {
        e.printStackTrace();
    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
    return null;
}



public String decrypt(String str) {

    try {

        // Decode base64 to get bytes
        byte[] dec = new sun.misc.BASE64Decoder().decodeBuffer(str);
        System.out.println( "[decrypt]BASE64Decoded????? " + dec );
        System.out.println( "[decrypt]Algo: " + dcipher.getAlgorithm() );
        System.out.println( "[decrypt]Block Size: " + dcipher.getBlockSize() );
        System.out.println( "[decrypt]Parameters: " + dcipher.getParameters().getEncoded() );

        // Decrypt
        byte[] utf8 = dcipher.doFinal(dec);

        // Decode using utf-8
        return new String(utf8, "UTF8");

    } catch (BadPaddingException e) {
        e.printStackTrace();
    } catch (IllegalBlockSizeException e) {
        e.printStackTrace();
    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
    return null;
}

}

Edit-Added Debugging Log

Encrypted: HS/uG4F/TZEN/lzX4xGvEQ==
[decrypt]BASE64Decoded????? [B@18df65f
[decrypt]Algo: PBEWithMD5AndDES
[decrypt]Block Size: 8
[decrypt]Parameters: [B@1139ac8

Better Logging Data

Encrypted: HS/uG4F/TZEN/lzX4xGvEQ==
[decrypt]BASE64Decoded????? [B@11b7a20
[decrypt]BASE64Decoded String??? 1D 2F EE 1B 81 7F 4D 91 0D FE 5C D7 E3 11 AF 11 
[decrypt]BASE64Decoded Length: 16
[decrypt]Algo: PBEWithMD5AndDES
[decrypt]Block Size: 8
[decrypt]Parameters: 30 0D 04 08 A9 9B C8 32 56 34 E3 03 02 01 13 
[decrypt]After decryption:68 71 53 69 64 5F 37 36 39 
Decrypted: hqSid_769

Added more logging after synchronizing function

Request data: hqSid_3443
[encrypt] String??? 68 71 53 69 64 5F 33 34 34 33
[encrypt] Encrypted??? C7 02 03 2D BD F9 A6 6A 93 C0 40 48 2E 5F 2B E5
[encrypt]Encrypted ï¿½-ï¿½ï¿½jï¿½ï¿½@H._+ï¿½
[encrypt]Encrypted Length 16
[encrypt]Algo: PBEWithMD5AndDES
[encrypt]Block Size: 8
[encrypt]Parameters: [B@f5cbda

received

Encrypted: xwIDLb35pmqTwEBILl8r5Q==
[decrypt]BASE64Decoded????? [B@13cd5ba
[decrypt]BASE64Decoded String??? C7 02 03 2D BD F9 A6 6A 93 C0 40 48 2E 5F 2B E5
[decrypt]BASE64Decoded Length: 16
[decrypt]Algo: PBEWithMD5AndDES
[decrypt]Block Size: 8
[decrypt]dcipher.Parameters().getEncoded(): 30 0D 04 08 A9 9B C8 32 56 34 E3 03 02 01 13
javax.crypto.BadPaddingException: Given final block not properly padded...

look here. http://stackoverflow.com/questions/8049872/given-final-block-not-properly-padded — ditkin, May 29 '12 at 06:21
I'm rather new to cryptography and I'm still trying to understand the link posted by ditkin. What I'm still trying to get is why restarting my tomcat fix it? =/ — Jeff, May 29 '12 at 07:10
@Jeff what is the debugging output you get when you run your code (both encrypt and decrypt)? — Christopher Schultz, May 29 '12 at 19:00
@ChristopherSchultz I Added the debugging log for the decryption above... After the last log... it returns NULL, which I think is logical since an exception was thrown =/ Encryption doesn't have any logs, since it didnt fail... what do have in mind that I will log on the encryption side? — Jeff, May 30 '12 at 02:53
Both your base64decoded and "parameters" values are byte arrays. Can you fix the code to expand those and write-out the byte values? It looks like @ditkin is suggesting that you simply have the wrong decryption key. Is that possible? — Christopher Schultz, May 30 '12 at 14:39
@ChristopherSchultz updated logs above, thanks! :) P.s.: The newer log is the successful one.. as of the moment, I have not captured any exception logs, gonna have to do some waiting game agian :( — Jeff, May 31 '12 at 06:35
This code is not thread-safe. Is that a possible problem, here? What does your driver code look like? Also, instrument the 'encrypt' operation and show that output. — Christopher Schultz, May 31 '12 at 16:04
I made the function synchronized ( thread safe ) and ill see if this fixes anything but i doubt it since only one app is sending the encrypted data to the decrypter :/ — Jeff, Jun 01 '12 at 04:53
little update.. so far no exceptions... could i have been wrong with the threading? =/ — Jeff, Jun 02 '12 at 06:56
@ChristopherSchultz bad news.. didnt work.. still got the error..updated the logs above... — Jeff, Jun 04 '12 at 08:32
also, im reading around to try BouncyCastle APIs.... hope that would help... — Jeff, Jun 04 '12 at 09:03
Using BC probably won't change anything. But, if you re-write all your code you may fix the bug without knowing why. — Christopher Schultz, Jun 04 '12 at 13:58

Christopher Schultz · Accepted Answer · 2012-06-06T18:54:26.547

2

This code is definitely not threadsafe, and it appears to be the problem. You will need to use a different Cipher object for each thread.

edited Jun 06 '12 at 18:54

answered Jun 04 '12 at 14:03

Christopher Schultz

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Hmmm... not sure about the password since I stored the password/salt in our mysql database... ill try to log it if the password was retrieved properly.. – Jeff Jun 05 '12 at 01:29
1

FWIW, a constant salt isn't really a salt. You should use a random salt and store it with the hashed password. – Christopher Schultz Jun 05 '12 at 14:46
wow... so far so good.. whole day no exception... What happened before was that I placed the class above inside a Singleton so that I can reuse it over again.... I changed it so that every call it creates a new object of the class above... =/ – Jeff Jun 06 '12 at 06:47
Looks like my comment about threadsafety was probably the read problem: you can't share a Cipher instance across threads or nothing will work properly because all threads will use the same cipher objects and create chaos. I'll edit the answer to reflect that. – Christopher Schultz Jun 06 '12 at 18:52
I will do more testing but this made good progress ^_^ One question though, anywhere I can look into more about cryptography and best practices? – Jeff Jun 07 '12 at 07:11
That's a fairly open-ended question. Go to the library or a bookstore and browse the crypto section looking for things that appear to meet your needs. As for best coding practices: unless a class claims that it (or subclasses of it) are thread-safe, you certainly don't want to try to share them amongst threads without synchronizing access. Ciphers aren't that heavyweight anyway, so sharing one between threads doesn't really buy you anything -- it just makes things worse as you've seen. – Christopher Schultz Jun 07 '12 at 14:24

Java "Given final block not properly padded" Exception in Tomcat5.5 Server

1 Answers1