Javax.crypto.BadPaddingException: unknown block type - URGENT

Question

I am trying to encryp-decrypt a file (serialized xml file ) using BC provider with RSA algorithm and PKCS1Padding padding..
Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding", "BC")
Sequence of action is encrypt - base64encode -
base64decode - decrypt.
Encryption seems to be working fine but while decrypting it gives the error mentioned below:
javax.crypto.BadPaddingException: unknown block type
I tried using OAEPPadding - In that scenario I get this error
javax.crypto.BadPaddingException: data hash wrong
I tried searching the cause and resolution of the problems on various resources on net but in vain. Need it urgently. PLS HELP. THANKS
I am pasting my code below :
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.security.Key;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Security;
import java.security.spec.EncodedKeySpec;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import javax.crypto.Cipher;
import org.apache.log4j.Logger;
import org.bouncycastle.jce.provider.*;
import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;
public class EncryptBase64File
protected static final String ALGORITHM = "RSA";
     private static Logger logger = Logger.getLogger(EncryptFiles.class.getClass());
private EncryptBase64File()
* Init java security to add BouncyCastle as an RSA provider
public static void init()
Security.addProvider(new BouncyCastleProvider());
* Generate key which contains a pair of privae and public key using 1024 bytes
* @return key pair
* @throws NoSuchAlgorithmException
public static KeyPair generateKey() throws NoSuchProviderException,NoSuchAlgorithmException
//KeyPairGenerator keyGen = KeyPairGenerator.getInstance(ALGORITHM);
          KeyPairGenerator keyGen =
                              KeyPairGenerator.getInstance("RSA", "BC");
keyGen.initialize(1024);
KeyPair key = keyGen.generateKeyPair();
return key;
* Encrypt a text using public key.
* @param text The original unencrypted text
* @param key The public key
* @return Encrypted text
* @throws java.lang.Exception
public static byte[] encrypt(byte[] text, PublicKey key) throws Exception
byte[] cipherText = null;
try
// get an RSA cipher object and print the provider
Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding", "BC");
               //Cipher cipher = Cipher.getInstance("RSA");
               System.out.println("\nProvider is: " + cipher.getProvider().getInfo());
               System.out.println("\nStart encryption with public key");
if (logger.isDebugEnabled())
                    logger.debug("\nProvider is: " + cipher.getProvider().getInfo());
                    logger.debug("\nStart encryption with public key");
// encrypt the plaintext using the public key
cipher.init(Cipher.ENCRYPT_MODE, key);
cipherText = cipher.doFinal(text);
catch (Exception e)
               logger.error(e, e);
throw e;
return cipherText;
* Encrypt a text using public key. The result is enctypted BASE64 encoded text
* @param text The original unencrypted text
* @param key The public key
* @return Encrypted text encoded as BASE64
* @throws java.lang.Exception
public static String encrypt(String text, PublicKey key) throws Exception
String encryptedText;
try
byte[] cipherText = encrypt(text.getBytes("UTF8"),key);
encryptedText = encodeBASE64(cipherText);
               System.out.println("Enctypted text is: " + encryptedText);
               logger.debug("Enctypted text is: " + encryptedText);
catch (Exception e)
               logger.error(e, e);
throw e;
return encryptedText;
* Decrypt text using private key
* @param text The encrypted text
* @param key The private key
* @return The unencrypted text
* @throws java.lang.Exception
public static byte[] decrypt(byte[] text, PrivateKey key) throws Exception
byte[] dectyptedText = null;
try
// decrypt the text using the private key
//Cipher cipher = Cipher.getInstance("RSA/CBC/PKCS1Padding","BC");
               Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding", "BC");
               //Cipher cipher = Cipher.getInstance("RSA");
               logger.debug("Start decryption");
               System.out.println("Start decryption");
cipher.init(Cipher.DECRYPT_MODE, key);
dectyptedText = cipher.doFinal(text);
catch (Exception e)
               logger.error(e, e);
throw e;
return dectyptedText;
* Decrypt BASE64 encoded text using private key
* @param text The encrypted text, encoded as BASE64
* @param key The private key
* @return The unencrypted text encoded as UTF8
* @throws java.lang.Exception
public static String decrypt(String text, PrivateKey key) throws Exception
String result;
try
// decrypt the text using the private key
byte[] dectyptedText = decrypt(decodeBASE64(text),key);
result = new String(dectyptedText, "UTF8");
               logger.debug("Decrypted text is: " + result);
catch (Exception e)
               logger.error(e, e);
throw e;
return result;
* Encode bytes array to BASE64 string
* @param bytes
* @return Encoded string
private static String encodeBASE64(byte[] bytes)
BASE64Encoder b64 = new BASE64Encoder();
return b64.encode(bytes);
* Decode BASE64 encoded string to bytes array
* @param text The string
* @return Bytes array
* @throws IOException
private static byte[] decodeBASE64(String text) throws IOException
BASE64Decoder b64 = new BASE64Decoder();
return b64.decodeBuffer(text);
* Encrypt file using 1024 RSA encryption
* @param srcFileName Source file name
* @param destFileName Destination file name
* @param key The key. For encryption this is the Private Key and for decryption this is the public key
* @param cipherMode Cipher Mode
* @throws Exception
public static void encryptFile(String srcFileName, String destFileName, PublicKey key) throws Exception
encryptDecryptFile(srcFileName,destFileName, key, Cipher.ENCRYPT_MODE);
* Decrypt file using 1024 RSA encryption
* @param srcFileName Source file name
* @param destFileName Destination file name
* @param key The key. For encryption this is the Private Key and for decryption this is the public key
* @param cipherMode Cipher Mode
* @throws Exception
public static void decryptFile(String srcFileName, String destFileName, PrivateKey key) throws Exception
encryptDecryptFile(srcFileName,destFileName, key, Cipher.DECRYPT_MODE);
* Encrypt and Decrypt files using 1024 RSA encryption
* @param srcFileName Source file name
* @param destFileName Destination file name
* @param key The key. For encryption this is the Private Key and for decryption this is the public key
* @param cipherMode Cipher Mode
* @throws Exception
public static void encryptDecryptFile(String srcFileName, String destFileName, Key key, int cipherMode) throws Exception
OutputStream outputWriter = null;
InputStream inputReader = null;
try
          Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding", "BC");
String textLine = null;
byte[] buf = cipherMode == Cipher.ENCRYPT_MODE? new byte[100] : new byte[128];
int newBuffer;
// init the Cipher object for Encryption...
cipher.init(cipherMode, key);
// start FileIO
outputWriter = new FileOutputStream(destFileName);
inputReader = new FileInputStream(srcFileName);
while ( (bufl = inputReader.read(buf)) != -1)
String encText = null;
String base64EncText = null ;
if (cipherMode == Cipher.ENCRYPT_MODE)
encText = encrypt(getBytes(buf,newBuffer).toString(),(PublicKey)key);
else
encText = decrypt(getBytes(buf,newBuffer).toString(),(PrivateKey)key);
               outputWriter.write(encText.getBytes());
outputWriter.flush();
catch (Exception e)
               logger.error(e,e);
throw e;
finally
try
if (outputWriter != null)
outputWriter.close();
if (inputReader != null)
inputReader.close();
catch (Exception e)
public static byte[] getBytes(byte[] arr, int length)
byte[] newArr = null;
if (arr.length == length)
newArr = arr;
else
newArr = new byte[length];
for (int i = 0; i < length; i++)
newArr[i] = (byte) arr;
return newArr;
     public static void main(String args[])
          throws Exception
          init();
          KeyPair keyPair = generateKey();
          PublicKey pubKey = keyPair.getPublic();
          PrivateKey privKey = keyPair.getPrivate();
          encryptFile("C:\\Temp\\TestFile.xml","C:\\Temp\\RSAEncryptedText.xml",pubKey);
          decryptFile("C:\\Temp\\RSAEncryptedText.xml","C:\\Temp\\RSADecryptedText.xml",privKey);

Answer 1

I think you are the same poster as 'contebral'. Why the multiple identities?
First off, the code you posted doesn't even compile. The getBytes() method has an error. Also, in method encryptDecryptFile() the variable bufl is not declared.
The rest of the code is a mess. The toString() method does not do what you think it does; you're just going to get the object reference id. There is no reason to keep converting to/from byte arrays and Strings. Most of the time your data should be kept as a byte array, only possibly converting for I/O operations.
The size of the base64 encoded output is not 128 bytes, it is 172 bytes. At this point I ran out of patience and stopped looking.
There is no shame in being a beginner in Java, but you must walk before you can run. Stop running.