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File Encryption And Decryption In Java, doesn't work decryption

Hi guys I have to do this and I can encrypt file according to the des algorithm but I can not decyrpt again file ,I recieve error messaje like that :
javax.crypto.BadPaddingException Given final block not properly padded
I can not decrypt file I couldnt find why. Can u help me please
Thank you guys.
JAVA CODE :
public class Sifreleme {
public static void encrypt(){
try {
SecretKey key = KeyGenerator.getInstance("DES").generateKey();
FileOutputStream fosKey = new FileOutputStream("..\\KEY");
SecretKeyFactory keyfac = SecretKeyFactory.getInstance("DES");
DESKeySpec keyspec = (DESKeySpec) keyfac.getKeySpec(key, DESKeySpec.class);
fosKey.write(keyspec.getKey());
fosKey.close();
Cipher crypt = Cipher.getInstance("DES");
crypt.init(Cipher.ENCRYPT_MODE, key);
FileInputStream fis = new FileInputStream("C:\\Users\\akif\\Desktop\\zilsesi.mp3");
FileOutputStream fos = new FileOutputStream("C:\\Users\\akif\\Desktop\\sifrelenenzilsesi.mp3");
byte[] arrayBytes = new byte[8];
int bytesReads;
while ((bytesReads = fis.read(arrayBytes)) != -1) {
fos.write(crypt.doFinal(arrayBytes), 0, bytesReads);
}
fis.close();
fos.close();
} catch (Exception e) {
e.printStackTrace();
}
}
public static void decrypt(){
try {
FileInputStream fisKey = new FileInputStream("..\\KEY");
byte[] arrayKey = new byte[fisKey.available()];
fisKey.read(arrayKey);
SecretKey key = new SecretKeySpec(arrayKey, "DES");
Cipher decrypt = Cipher.getInstance("DES");
decrypt.init(Cipher.DECRYPT_MODE, key);
FileInputStream fis = new FileInputStream("C:\\Users\\akif\\Desktop\\sifrelenenzilsesi.mp3");
byte[] encText = new byte[16];
int bytesReads;
while ((bytesReads = fis.read(encText)) != -1) {
fis.read(decrypt.doFinal(encText), 0, bytesReads);
}
fis.close();
System.out.println(new String(encText));
} catch (Exception e) {
e.printStackTrace();
}
}
public static void main(String []args) throws IOException{
encrypt();
decrypt();
}

Your code here:
while ((bytesReads = fis.read(encText)) != -1) {
fis.read(decrypt.doFinal(encText), 0, bytesReads);
}
Is rather obviously wrong: you need to write the plaintext generated by calling decrypt.doFinal just like you do during encryption. Currently you are overwriting the generated plaintext by the next block(s) of ciphertext because you call read twice in the loop.
Furthermore, depending on your DES Cipher implementation, you forgot about the IV.
A lot of other things are wrong as well, including:
the stream handling using getAvailable();
the use of the 56 bit DES cipher;
the use of ECB mode;
the repeated calls to doFinal (which results in a very large overhead and insecure code);
not using the CipherInputStream and CipherOutputStream (etcetera);
using a string as the key;
forgetting to close your streams when an exception occurs (use the try with resources);
the printStackTracke() exception handling;
the use of static fields as variables.
Using the platform encoding within new String(encText) is only likely wrong.
Note that using the wrong key / ciphertext combination will likely also result in this error.

Encrypt and Decrypt data with Meteor and Java

I have my application's UI built in Meteor and it gets and send the data from REST API (Spring CXF). I would like to encrypt the data in Meteor, and decrypt the same in REST API code. I am using AES for encryption and Decryption. In Meteor i am using https://atmospherejs.com/jparker/crypto-aes package for encryption. I have written the below code in java for decryption the encryption key send by Meteor.
public class AESTest {
private static String AESStr = "<Encrypted KEY>";
public static void main(String[] args) throws Exception {
Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
System.out.println(decrypt(AESStr, "Test"));
}
public static String decrypt(String responseStr, String passPhrase) throws GeneralSecurityException {
String decryptedStr = "";
try {
Cipher cipher = getCipher(Cipher.DECRYPT_MODE, passPhrase);
byte[] decoded = Base64.decodeBase64(responseStr.getBytes());
byte[] decryptedWithKey = cipher.doFinal(decoded);
byte[] decrypted = Arrays.copyOfRange(decryptedWithKey, 16, decryptedWithKey.length);
decryptedStr = new String(decrypted, "UTF-8");
} catch (Exception e) {
e.printStackTrace();
}
return decryptedStr;
}
private static Cipher getCipher(int mode, String passPhrase) throws Exception {
SecretKeySpec secretKeySpec = new SecretKeySpec(passPhrase.getBytes(), "AES");
byte[] IV = new byte[16];
new Random().nextBytes(IV);
AlgorithmParameterSpec paramSpec = new IvParameterSpec(IV);
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS7Padding");
cipher.init(mode, secretKeySpec, paramSpec);
return cipher;
}
}
When I run the code i am getting below exception
javax.crypto.BadPaddingException: pad block corrupted
at org.bouncycastle.jce.provider.JCEBlockCipher.engineDoFinal(Unknown Source)
at javax.crypto.Cipher.doFinal(Cipher.java:2165)
at com.tph.r3.EncodeTest.decrypt(EncodeTest.java:37)
at com.tph.r3.EncodeTest.main(EncodeTest.java:26)
Can anyone guide me with the issue?

There is a problem with the decryption logic w.r.t IV. You are selecting an IV randomly to initialize decryption cipher which is wrong. You need to use the same IV that was used to encrypt the responseStr which forms its first 16 bytes usually.
In the current form your getCipher() can be used only for encryption where IV is selected randomly but not for decryption. Better write another method.
Psuedocode for decryption:
decCipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
SecretKeySpec keySpec = new SecretKeySpec(securityKey , "AES");
//IV + Cipher
byte [] cipherWithIV = Base64.decodeBase64(responseStr.getBytes()));
//Extract IV
byte [] iv = new byte [16];
byte [] cipherWithoutIV = new byte [cipherWithIV.length - 16 ];
//First 16 bytes
for(i < 16; i++) {
iv [i] = cipherWithIV [i];
}
//Rest of the cipher ie 16 -> cipherWithIV.length
for(i < cipherWithIV.length; i++) {
cipherWithoutIV [j] = cipherWithIV[i];
j++;
}
//
IvParameterSpec ivParamSpec = new IvParameterSpec(iv);
//
decCipher.init(Cipher.DECRYPT_MODE, keySpec, ivParamSpec);
//Decrypt cipher without IV
decText = decCipher.doFinal(cipherWithoutIV);
//Convert to string
decString = new String(decText,"UTF8");

android cipher doesn't decrypt first 16 bytes / characters of encrypted data

I am working on a file encryption/decryption app. I am using a simple .txt file for testing. When I select the file from within the app and choose to encrypt, the entire file data is encrypted. However, when I decrypt only part of the file data gets decrypted. For some reason the first 16 bytes/characters doesn't get decrypted.
test_file.txt contents: "This sentence is used to check file encryption/decryption results."
encryption result: "¾mÁSTÐÿT:Y­„"O¤]ÞPÕµß~ëqrÈb×ßq²¨†ldµJ,O|56\e^-’#þûÝû"
decryption result: "£ÿÒÜÑàh]VÄþ„- used to check file encryption/decryption results."
There aren't any errors in the logcat.
What am I doing wrong?
Method to encrypt file:
public void encryptFile(String password, String filePath) {
byte[] encryptedFileData = null;
byte[] fileData = null;
try {
fileData = readFile(filePath);//method provided below
// 64 bit salt for testing only
byte[] salt = "goodsalt".getBytes("UTF-8");
SecretKey key = generateKey(password.toCharArray(), salt);//method provided below
byte[] keyData = key.getEncoded();
SecretKeySpec sKeySpec = new SecretKeySpec(keyData, "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
cipher.init(Cipher.ENCRYPT_MODE, sKeySpec);
encryptedFileData = cipher.doFinal(fileData);
saveData(encryptedFileData, filePath);//method provided below
}
catch (Exception e) {
e.printStackTrace();
}
}
Method to read file content:
public byte[] readFile(String filePath) {
byte[] fileData;
File file = new File(filePath);
int size = (int) file.length();
fileData = new byte[size];
try {
BufferedInputStream inputStream = new BufferedInputStream(new FileInputStream(file));
inputStream.read(fileData);
inputStream.close();
}
catch (FileNotFoundException e) {
e.printStackTrace();
}
catch (IOException e) {
e.printStackTrace();
}
return fileData;
}
Method to generate secret key:
private SecretKey generateKey(char[] password, byte[] salt) throws NoSuchAlgorithmException, InvalidKeySpecException {
// Number of PBKDF2 hardening rounds to use. Larger values increase computation time. You
// should select a value that causes computation to take >100ms.
final int iterations = 1000;
// Generate a 256-bit key
final int outputKeyLength = 256;
SecretKeyFactory secretKeyFactory;
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
// Use compatibility key factory -- only uses lower 8-bits of passphrase chars
secretKeyFactory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1And8bit");
}
else {
// Traditional key factory. Will use lower 8-bits of passphrase chars on
// older Android versions (API level 18 and lower) and all available bits
// on KitKat and newer (API level 19 and higher).
secretKeyFactory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
}
KeySpec keySpec = new PBEKeySpec(password, salt, iterations, outputKeyLength);
return secretKeyFactory.generateSecret(keySpec);
}
Method to save encrypted/decrypted data to the file:
private void saveData(byte[] newFileData, String filePath) {
File file = new File(filePath);
try {
BufferedOutputStream outputStream = new BufferedOutputStream(new FileOutputStream(file));
outputStream.write(newFileData);
outputStream.flush();
outputStream.close();
}
catch (IOException e) {
e.printStackTrace();
}
}
Method to decrypt file:
public void decryptFile(String password, String filePath) {
byte[] decryptedFileData = null;
byte[] fileData = null;
try {
fileData = readFile(filePath);
byte[] salt = "goodsalt".getBytes("UTF-8");//generateSalt();
SecretKey key = generateKey(password.toCharArray(), salt);
byte[] keyData = key.getEncoded();
SecretKeySpec sKeySpec = new SecretKeySpec(keyData, "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
cipher.init(Cipher.DECRYPT_MODE, sKeySpec);
decryptedFileData = cipher.doFinal(fileData);
saveData(decryptedFileData, filePath);
}
catch (Exception e) {
e.printStackTrace();
}
}
This line of code encrypts the file:
//simple password for testing only
encryptor.encryptFile("password", "storage/emulated/0/Download/test_file.txt");
This line decrypts the file:
encryptor.decryptFile("password", "storage/emulated/0/Download/test_file.txt");
Edit: Thanks to DarkSquirrel42 and Oncaphillis. You guys are awesome!
Adding this line of code to both encrypt and decrypt functions solved my problem.
//note: the initialization vector (IV) must be 16 bytes in this case
//so, if a user password is being used to create it, measures must
//be taken to ensure proper IV length; random iv is best and should be
//stored, possibly alongside the encrypted data
IvParameterSpec ivSpec = new IvParameterSpec(password.getBytes("UTF-8"));
and then,
cipher.init(Cipher.XXXXXXX_MODE, sKeySpec, ivSpec);

your problem has something to do with the cipher's mode of operation ... cbc, or cipher block chaining mode
in general CBC is simple ... take whatever the output of your previous encryiption block was, and xor that onto the current input before encrypting it
for the first block we obviously have a problem... there is no previous block ... therefore we introduce something called IV ... an initialisation vector ... a block ength of random bytes ...
now ... as you can imagine, you will need the same IV when you want to decrypt ...
since you don't save that, the AES implementation will give you a random IV every time ...
therefore you don't have all information to decrypt block 1 ... which is the first 16 bytes in case of AES ...
when handling CBC mode data, it's allways a good choice to simply prepend the used IV in your cypertext output ... the IV shall just be random ... it is no secret ...

Like #ÐarkSquirrel42 already points out the en/decrytion routine for CBC seems to interpret the first 16 bytes as an initialisation vector. This worked for me:
// got to be random
byte[] iv = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
IvParameterSpec ivspec = new IvParameterSpec(iv);
cipher.init(Cipher.XXXXX_MODE, sKeySpec,ivspec);

javax.crypto.BadPaddingException: pad block corrupted

I'm trying to encrypt something, and decrypt it. I'm failing on the decryption - I get the exception above. I tried changing ctLength and ptLength, but to no avail. What am I doing wrong?
I'm trying to encrypt: 0 0 0 0 0 0 0 0
private Cipher encrypt(byte[] input)
{
try
{
SecretKeySpec key = new SecretKeySpec(keyBytes, "AES");
Cipher cipher = Cipher.getInstance("AES/ECB/PKCS7Padding", "BC");
// encryption pass
cipher.init(Cipher.ENCRYPT_MODE, key);
byte[] cipherText = new byte[cipher.getOutputSize(input.length)];
int ctLength = cipher.update(input, 0, input.length, cipherText, 0);
ctLength += cipher.doFinal(cipherText, ctLength);
FileOutputStream fs = new FileOutputStream(savedScoresFileName);
fs.write(cipherText);
return cipher;
}
catch (Exception e)
{
Log.e("encrtypt", "Exception", e);
}
return null;
}
private String decrypt()
{
try
{
Cipher cipher = Cipher.getInstance("AES/ECB/PKCS7Padding", "BC");
SecretKeySpec key = new SecretKeySpec(keyBytes, "AES");
byte[] cipherText = new byte[32];
FileInputStream fl = new FileInputStream(savedScoresFileName);
fl.read(cipherText);
cipher.init(Cipher.DECRYPT_MODE, key);
byte[] plainText = new byte[cipher.getOutputSize(32)];
int ptLength = cipher.update(cipherText, 0, 32, plainText, 0);
ptLength += cipher.doFinal(plainText, ptLength);
return new String(plainText).substring(0, ptLength);
}
catch (Exception e)
{
Log.e("decrypt", "Exception", e);
}
return null;
}
This code was copied from this, which worked.

Your code has a number of issues, but your problem is caused by your file reading code and your strange method of performing the encryption and decryption.
Don't use the update() method, just use doFinal() and correct your file writing/reading code. E.g. your decryption method should look something like:
try {
Cipher cipher = Cipher.getInstance("AES/ECB/PKCS7Padding", "BC");
SecretKeySpec key = new SecretKeySpec(keyBytes, "AES");
// Here you need to accurately and correctly read your file into a byte
// array. Either Google for a decent solution (there are many out there)
// or use an existing implementation, such as Apache Commons commons-io.
// Your existing effort is buggy and doesn't close its resources.
byte[] cipherText = FileUtils.readFileToByteArray(new File(savedScoresFileName));
cipher.init(Cipher.DECRYPT_MODE, key);
// Just one call to doFinal
byte[] plainText = cipher.doFinal(cipherText);
// Note: don't do this. If you create a string from a byte array,
// PLEASE pass a charset otherwise your result is platform dependent.
return new String(plainText);
} catch (Exception e) {
e.printStackTrace();
}

javax.crypto.BadPaddingException: Given final block not properly padded error while decryption

I am doing encryption and decryption of data as follows but getting error
protected Cipher aes_Gen_with_Key(byte[] key)
{
Cipher cipher=null;
try
{
byte[] key_hash = (key).toString().getBytes("UTF-8");
key_hash = Arrays.copyOf(key_hash, 32); // use only first 256 bit
SecretKeySpec secretKeySpec = new SecretKeySpec(key_hash, "AES");
cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec);
} catch (Exception e) {
System.out.println("Error Occured");
}
return cipher;
}
protected Cipher aes_Dec_with_Key(byte[] key,byte[] iv)
{
Cipher cipher=null;
try
{
byte[] key_hash = (key).toString().getBytes("UTF-8");
key_hash = Arrays.copyOf(key_hash, 32); // use only first 256 bit
SecretKeySpec secretKeySpec = new SecretKeySpec(key_hash, "AES");
cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
cipher.init(Cipher.DECRYPT_MODE,secretKeySpec,new IvParameterSpec(iv));
}
catch (Exception e) {
System.out.println(e);
}
return cipher;
}
With above 2 functions I am getting ciphers with which I am doing encryption and decryption, but getting javax.crypto.BadPaddingException: Given final block not properly padded as error. Length of decryption byte array is 752 and IV at decryption is 16 byte long. Can any one suggest?
Here are few more relevant code blocks.
Apologies for invalid use java naming conventions
// Key Class
import java.io.Serializable;
#SuppressWarnings("serial")
public class Key implements Serializable{
byte[] gsmodp_hash=null;
byte[] iv_pass=null;
byte[] Nonce_Enc=null;
byte[] iv_non=null;
public Key() {
}
public Key(byte[] gsmodp_hash,byte[] iv_pass,byte[] Nonce_Enc,byte[] iv_non) {
this.gsmodp_hash=gsmodp_hash;
this.iv_pass=iv_pass;
this.Nonce_Enc=Nonce_Enc;
this.iv_non=iv_non;
}
}
// Client side code
JSONObject auth_step_obj=new JSONObject();
try {
BigInteger gsmodp=get_modu_frm_server(receivePacket);
BigInteger R2=get_R2_frm_server(receivePacket);
BigInteger N2=get_N2_frm_server(receivePacket);
N2=crypto.dec_NonceG(N2);
BigInteger a=crypto.get_RandLong();
BigInteger gamodp= crypto.dh_GenerationG(a, crypto.g, crypto.p);
BigInteger key=crypto.dh_GenerationG(a, gsmodp, crypto.p);
// Got hash of g^abmodp
byte[] dhkey=crypto.sha256G(key.toString());
key=null;
//Mixing passwords
SecretKey secretkey=(SecretKey) userCredentials.get("password");
byte[] mixed_hash=crypto.passwordMixerG(R2, secretkey.getEncoded());
//Working Fine Till now
// Getting Cipher for encrypting gsmodp using password and nonce
Cipher cipher_password=crypto.aes_Gen_with_Key(mixed_hash);
Cipher cipher_key=crypto.aes_Gen_with_Key(dhkey);
// Generating quantities for JSON Object
byte[] gsmodp_hash=cipher_password.doFinal(gamodp.toString().getBytes());
byte[] gsmodp_hash_iv=cipher_password.getIV();
byte[] nonce_enc=cipher_key.doFinal(N2.toString().getBytes());
byte[] nonce_enc_iv=cipher_key.getIV();
Key authetication_parameters=new Key(gsmodp_hash,gsmodp_hash_iv,nonce_enc,nonce_enc_iv);
auth_step_obj.put("obj",authetication_parameters);
} catch (Exception e) {
// TODO Auto-generated catch block
System.out.println("Hi:sec_DH_Step");
}
// This sends JSONObject to calling method which generates UDP packet and sends to server
return auth_step_obj;
}
// Server side code
// Once packet received on server following happens
ds.receive(receivePacket);
SecretKey userKey=cryptoObj.get_from_KeyStoreG(user_name);
// Adding R2 and userKey byte by byte
byte[] mixed_hash=cryptoObj.passwordMixerG(R2, userKey.getEncoded());
JSONObject authentication_nonce=new JSONObject();
authentication_nonce=cryptoObj.readRecievedPacket(receivePacket);
Key obj=(Key)authentication_nonce.get("obj");
Cipher cipher=cryptoObj.aes_Dec_with_Key(mixed_hash,obj.iv_pass);
// I am getting error on do final
System.out.println(new String(cipher.doFinal(obj.gsmodp_hash)));

The code you presented works just fine. The error must lie in the code you haven't shared with us (i.e. the code that actually uses the Cipher objects).
I wrote the code below to test your question code:
public static void main(String[] args) throws Exception {
Random random = new Random();
byte[] key = new byte[32];
random.nextBytes(key);
byte[] plaintext = new byte[100];
random.nextBytes(plaintext);
Cipher enc = aes_Gen_with_Key(key);
byte[] ciphertext = enc.doFinal(plaintext);
byte[] iv = enc.getIV();
Cipher dec = aes_Dec_with_Key(key, iv);
byte[] recoveredPlaintext = dec.doFinal(ciphertext);
System.out.println(Arrays.equals(plaintext, recoveredPlaintext));
}
Note, I made your two methods static. You should do the same, as they don't use any instance variables.