Develop Reference

Decrypt Video File and save to internal storage

I have an encrypted video with the key and I want to decrypt that video file with Key but I am not able to decrypt the video file. I try 2 3 methods but Non of these works for me.
Crypto.Class
public class Crypto {
static void fileProcessor(int cipherMode,String key,File inputFile,File outputFile){
try {
KeyGenerator keyGenerator = KeyGenerator.getInstance("AES");
SecureRandom secureRandom = new SecureRandom();
secureRandom.setSeed(key.getBytes("UTF-8"));
keyGenerator.init(128, secureRandom);
SecretKey secretKey = keyGenerator.generateKey();
// Key secretKey = new SecretKeySpec(key.getBytes(), "AES");
Cipher cipher = Cipher.getInstance("AES");
cipher.init(cipherMode, secretKey);
FileInputStream inputStream = null;
byte[] inputBytes = new byte[0];
try {
inputStream = new FileInputStream(inputFile);
inputBytes = new byte[(int) inputFile.length()];
inputStream.read(inputBytes);
} catch (IOException e) {
e.printStackTrace();
}
byte[] outputBytes = cipher.doFinal(inputBytes);
FileOutputStream outputStream = new FileOutputStream(outputFile);
outputStream.write(outputBytes);
inputStream.close();
outputStream.close();
} catch (NoSuchPaddingException | NoSuchAlgorithmException
| InvalidKeyException | BadPaddingException
| IllegalBlockSizeException | IOException e) {
e.printStackTrace();
}
}
public static String Decrypt(String filePath) {
String key = "my_encrypted_key";
// File inputFile = new File("text.txt");
File encryptedFile = new File(filePath);
String decryptedFilePath="";
//check special guid folder if not exist create
//get the selected video file path with settings path if exist decrypt if not exist show message
File decryptedFile = new File(decryptedFilePath);
try {
//Crypto.fileProcessor(Cipher.ENCRYPT_MODE,key,inputFile,encryptedFile);
Crypto.fileProcessor(Cipher.DECRYPT_MODE,key,encryptedFile,decryptedFile);
Log.d("success", "Decrypt: success");
return decryptedFile.getAbsolutePath();
} catch (Exception ex) {
System.out.println(ex.getMessage());
ex.printStackTrace();
}
return "";
}
}
But this does not work for me and I try another one.
public static void TEST2(String orgFile) {
try {
String password = "estudies741852963#123";
File outFile_dec = new File(Environment.getExternalStorageDirectory()+"/testVideo/abc.mp4");
if(!outFile_dec.isDirectory()) {
outFile_dec.mkdir();
}
if(!outFile_dec.exists()){
outFile_dec.createNewFile();
}
// reading the salt
// user should have secure mechanism to transfer the
// salt, iv and password to the recipient
FileInputStream saltFis = new FileInputStream(orgFile);
byte[] salt = new byte[8];
saltFis.read(salt);
saltFis.close();
// reading the iv
FileInputStream ivFis = new FileInputStream(orgFile);
byte[] iv = new byte[16];
ivFis.read(iv);
ivFis.close();
SecretKeyFactory factory = SecretKeyFactory
.getInstance("PBKDF2WithHmacSHA1");
KeySpec keySpec = new PBEKeySpec(password.toCharArray(), salt, 1000,
256);
SecretKey tmp = factory.generateSecret(keySpec);
SecretKey secret = new SecretKeySpec(tmp.getEncoded(), "AES");
// file decryption
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
cipher.init(Cipher.DECRYPT_MODE, secret, new IvParameterSpec(iv));
InputStream fis = new FileInputStream(orgFile);
OutputStream fos = new FileOutputStream(outFile_dec);
// byte[] in = new byte[1024];
// int read;
// while ((read = fis.read(in)) != -1) {
// byte[] output = cipher.update(in, 0, read);
// if (output != null)
// fos.write(output);
// }
//
// byte[] output = cipher.doFinal();
// if (output != null)
// fos.write(output);
// fis.close();
// fos.flush();
// fos.close();
// System.out.println("File Decrypted.");
fos = new CipherOutputStream(fos, cipher);
int count = 0;
byte[] buffer = new byte[1024];
while ((count = fis.read(buffer)) >= 0) {
fos.write(buffer, 0, count);
}
fis.close();
fos.flush();
fos.close();
} catch (Exception e) {
e.printStackTrace();
}
}
In this method, its always shows on exception saying no such directory. And I try another method also But none of these works for me.
Tried this solution to decrypt my video
Java 256-bit AES Password-Based Encryption
How do i decrypt a file in Android with AES?

Encrypting and decrypting a file using CipherInputStream and CipherOutputStream

I've been trying to write an encrypted file in AES and decrypt it subsequently by using Cipher Streams provided in JCA. However, I'm having problems while reading the file, as the decryption is going haywire.
public class CipherStreams {
public static void main(String[] args) {
try {
KeyGenerator keygen = KeyGenerator.getInstance("AES");
Key k = keygen.generateKey();
Cipher aes = Cipher.getInstance("AES/ECB/PKCS5Padding");
aes.init(Cipher.ENCRYPT_MODE, k);
FileOutputStream fs = new FileOutputStream("Encrypyed.txt");
CipherOutputStream out = new CipherOutputStream(fs, aes);
out.write("[Hello:Okay]\nOkay".getBytes());
out.close();
Cipher aes2 = Cipher.getInstance("AES/ECB/PKCS5Padding");
aes2.init(Cipher.DECRYPT_MODE, k);
FileInputStream fis = new FileInputStream("Encrypyed.txt");
CipherInputStream in = new CipherInputStream(fis,aes2);
byte[] b = new byte[8];
int i = in.read(b);
while(i!=-1) {
System.out.print((char)i);
i = in.read(b);
}
} catch (NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException | IOException ex) {
Logger.getLogger(CipherStreams.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
I'm receiving a single byte output as 5. Can anyone please help point out the problem?

You're not writing the bytes read, you're writing the number of bytes being read.
You're also assuming that the default platform encoding just transforms each character to a byte.
Just do the reverse of what you did when writing: read everything, and transform the read byte array to a String, then print that string:
public class CipherStreams {
public static void main(String[] args) {
try {
KeyGenerator keygen = KeyGenerator.getInstance("AES");
Key k = keygen.generateKey();
Cipher aes = Cipher.getInstance("AES/ECB/PKCS5Padding");
aes.init(Cipher.ENCRYPT_MODE, k);
String fileName = "Encrypted.txt";
FileOutputStream fs = new FileOutputStream(fileName);
CipherOutputStream out = new CipherOutputStream(fs, aes);
out.write("[Hello:Okay]\nOkay".getBytes());
out.flush();
out.close();
Cipher aes2 = Cipher.getInstance("AES/ECB/PKCS5Padding");
aes2.init(Cipher.DECRYPT_MODE, k);
FileInputStream fis = new FileInputStream(fileName);
CipherInputStream in = new CipherInputStream(fis, aes2);
ByteArrayOutputStream baos = new ByteArrayOutputStream();
byte[] b = new byte[1024];
int numberOfBytedRead;
while ((numberOfBytedRead = in.read(b)) >= 0) {
baos.write(b, 0, numberOfBytedRead);
}
System.out.println(new String(baos.toByteArray()));
}
catch (NoSuchAlgorithmException | NoSuchPaddingException | InvalidKeyException | IOException ex) {
ex.printStackTrace();
;
}
}
}

How to generate AES/CBC/PKCS5Padding encrypted cipher in angularJs

I am working on a feature which require Aes encrypted (AES/CBC/PKCS5padding) cipher text to be sent from client to server which has ASP.Net in backend.
I've a decryption function on the server side as below :
public static string Decrypt(string inputBase64, string passphrase = null)
{
byte[] key, iv = new byte[0];
byte[] base64data = Convert.FromBase64String(inputBase64);
byte[] passphrasedata = RawBytesFromString(passphrase);
byte[] currentHash = new byte[0];
SHA256Managed hash = new SHA256Managed();
currentHash = hash.ComputeHash(passphrasedata);
return DecryptStringFromBytes(base64data, currentHash, null);
}
static string DecryptStringFromBytes(byte[] cipherText, byte[] Key, byte[] IV)
{
// Check arguments.
if (cipherText == null || cipherText.Length <= 0)
throw new ArgumentNullException("cipherText");
if (Key == null || Key.Length <= 0)
throw new ArgumentNullException("Key");
//if (IV == null || IV.Length <= 0)
// throw new ArgumentNullException("Key");
// Declare the string used to hold
// the decrypted text.
string plaintext = null;
// Create an RijndaelManaged object
// with the specified key and IV.
using (var cipher = new RijndaelManaged())
{
cipher.Key = Key;
cipher.IV = new byte[16];
//cipher.Mode = CipherMode.CBC;
//cipher.Padding = PaddingMode.PKCS7;
// Create a decrytor to perform the stream transform.
ICryptoTransform decryptor = cipher.CreateDecryptor(Key, cipher.IV);
// Create the streams used for decryption.
using (MemoryStream msDecrypt = new MemoryStream(cipherText))
{
using (CryptoStream csDecrypt = new CryptoStream(msDecrypt, decryptor, CryptoStreamMode.Read))
{
var bytes = default(byte[]);
using (StreamReader srDecrypt = new StreamReader(csDecrypt))
{
bytes = srDecrypt.CurrentEncoding.GetBytes(srDecrypt.ReadToEnd());
// Read the decrypted bytes from the decrypting stream
// and place them in a string.
//aintext = srDecrypt.ReadToEnd();
}
plaintext = ASCIIEncoding.UTF8.GetString(bytes, 0, bytes.Count());
}
}
}
return plaintext;
}
I want to implement an angularjs alternative to the following android code :
public static String Encrypt(String input, String passphrase)
{
if (input.equalsIgnoreCase("") || passphrase.equalsIgnoreCase(""))
return "";
else
{
byte[] key, iv;
byte[] passphrasedata = null;
try
{
passphrasedata = passphrase.getBytes("UTF-8");
}
catch (UnsupportedEncodingException e1)
{
e1.printStackTrace();
}
byte[] currentHash = new byte[0];
MessageDigest md = null;
try
{
md = MessageDigest.getInstance("SHA-256");
}
catch (NoSuchAlgorithmException e)
{
e.printStackTrace();
}
currentHash = md.digest(passphrasedata);
iv = new byte[16];
return Base64.encodeToString(EncryptStringToBytes(input, currentHash, iv), Base64.NO_WRAP);
}
}
static byte[] EncryptStringToBytes(String plainText, byte[] Key, byte[] IV)
{
if (plainText == null || plainText.length() <= 0)
{
Log.e("error", "plain text empty");
}
if (Key == null || Key.length <= 0)
{
Log.e("error", "key is empty");
}
if (IV == null || IV.length <= 0)
{
Log.e("error", "IV key empty");
}
byte[] encrypted;
try
{
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
SecretKeySpec myKey = new SecretKeySpec(Key, "AES");
IvParameterSpec IVKey = new IvParameterSpec(IV);
cipher.init(Cipher.ENCRYPT_MODE, myKey, IVKey);
encrypted = cipher.doFinal(plainText.getBytes("UTF-8"));
return encrypted;
}
catch (InvalidKeyException e)
{
e.printStackTrace();
}
catch (NoSuchAlgorithmException e)
{
e.printStackTrace();
}
catch (NoSuchPaddingException e)
{
e.printStackTrace();
}
catch (InvalidAlgorithmParameterException e)
{
e.printStackTrace();
}
catch (IllegalBlockSizeException e)
{
e.printStackTrace();
}
catch (BadPaddingException e)
{
e.printStackTrace();
}
catch (UnsupportedEncodingException e)
{
e.printStackTrace();
}
return null;
}
The Android code above is working fine. I want to implement the same encryption logic at AngularJs.
I've included CryptoJS library for SHA-256 and AES cipher calculation. Here is the code which I've implemented.
var password = '12345678';
var passwordHash = CryptoJS.SHA256(password).toString(CryptoJS.enc.Latin1);
var iv = CryptoJS.enc.Hex.parse('0000000000000000');
var cipher = CryptoJS.AES.encrypt(plaintext,passwordHash,{
iv: iv,
mode: CryptoJS.mode.CBC,
keySize: 256/32,
padding: CryptoJS.pad.Pkcs7
});
cipherText = cipher.ciphertext.toString(CryptoJS.enc.Base64);
The problem is that, the encoded string cannot be decrypted back to its previous form. I think there is some mismatch in the encryption logic in the client side and decryption logic on the server side.
When I pass the CryptoJS encrypted cipher to java decryption function, it shows errors:
javax.crypto.IllegalBlockSizeException: Input length must be multiple of 16 when decrypting with padded cipher
or sometimes:
javax.crypto.BadPaddingException: Given final block not properly padded

Thanks guys!!!, I got it working with the following code.
function hash (){
return CryptoJS.SHA256(password);
}
var cipher = (function(plaintext, password) {
passwordHash = hash(password);
var iv = CryptoJS.enc.Hex.parse('0000000000000000');
var cipher = CryptoJS.AES.encrypt(plaintext, passwordHash, {
iv: iv,
mode: CryptoJS.mode.CBC,
keySize: 256 / 32,
padding: CryptoJS.pad.Pkcs7
});
return cipher;
})(plaintext, password);
cipherBase64 = cipher.ciphertext.toString().hex2a().base64Encode();

calculate signature of classes.dex in android

i want to calculate the signature of classes.dex and
something like this
public byte[] computeSignature() throws IOException {
MessageDigest digest;
try {
digest = MessageDigest.getInstance("SHA-1");
} catch (NoSuchAlgorithmException e) {
throw new AssertionError();
}
byte[] buffer = new byte[8192];
ByteBuffer data = this.data.duplicate(); // positioned ByteBuffers aren't thread safe
data.limit(data.capacity());
data.position(SIGNATURE_OFFSET + SIGNATURE_SIZE);
while (data.hasRemaining()) {
int count = Math.min(buffer.length, data.remaining());
data.get(buffer, 0, count);
digest.update(buffer, 0, count);
}
return digest.digest();
}
but im confused
any help with proper code ?

javax.crypto.BadPaddingException

I am working on AES algorithm, and I have this exception which I couldn't solve.
javax.crypto.BadPaddingException: Given final block not properly padded
at com.sun.crypto.provider.SunJCE_f.b(DashoA13*..)
at com.sun.crypto.provider.SunJCE_f.b(DashoA13*..)
at com.sun.crypto.provider.AESCipher.engineDoFinal(DashoA13*..)
at javax.crypto.Cipher.doFinal(DashoA13*..)
the exception happens in the decryption part.
I initialize the key in a different place from where the decryption algorithm is
KeyGenerator kgen = KeyGenerator.getInstance("AES");//key generation for AES
kgen.init(128); // 192 and 256 bits may not be available
then I pass it with the cipher text which I read from file to the following method
public String decrypt(String message, SecretKey skey) {
byte[] raw = skey.getEncoded();
SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
// Instantiate the cipher
Cipher cipher;
byte[] original = null;
try {
cipher = Cipher.getInstance("AES");
cipher.init(Cipher.DECRYPT_MODE, skeySpec);
System.out.println("Original string: "
+ message);
original = cipher.doFinal(message.trim().getBytes()); //here where I got the exception
String originalString = new String(original);
}
//catches
EDIT
here's the encryption method.
public String encrypt(String message, SecretKey skey) {
byte[] raw = skey.getEncoded();
SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
// Instantiate the cipher
Cipher cipher;
byte[] encrypted = null;
try {
cipher = Cipher.getInstance("AES");
cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
encrypted = cipher.doFinal(message.getBytes());
System.out.println("raw is " + encrypted);
} catches
return asHex(encrypted);
}
and here's the asHex method
public static String asHex(byte buf[]) {
StringBuffer strbuf = new StringBuffer(buf.length * 2);
int i;
for (i = 0; i < buf.length; i++) {
if (((int) buf[i] & 0xff) < 0x10) {
strbuf.append("0");
}
strbuf.append(Long.toString((int) buf[i] & 0xff, 16));
}
return strbuf.toString();
}
Here's where I read the cipher text form the file
static public String readFile(String filePath) {
StringBuilder file = new StringBuilder();
String line = null;
try {
FileReader reader = new FileReader(filePath);
BufferedReader br = new BufferedReader(reader);
if (br != null) {
line = br.readLine();
while (line != null) {
file.append(line);
// System.out.println("line is " + line);
line = br.readLine();
}
}
br.close();
reader.close();
} catch (IOException ex) {
Logger.getLogger(FileManagement.class.getName()).log(Level.SEVERE, null, ex);
}
System.out.println("line is " + file.toString());
return String.valueOf(file);
}
can someone help?

Ok, so the problem is that you are converting the encrypted bytes to a hex string (using the asHex method) but are not converting the hex string back to a byte array correctly for decryption. You can't use getBytes.
You can use the following method to convert a hex string to a byte array:
public static byte[] fromHexString(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;
}
and then change your decrypt method to use:
original = cipher.doFinal(fromHexString(message));

I did have a Bad Padding Exception and have not been able to find on the internet a solution to my problem. Since I found it after some hard-working hours, I give it here.
My problem was, I was reading a file on my hard drive, and encrypting it through a buffer, always calling the doFinal() method instead of update() method. So when decrypting it, I had padding errors
input = new FileInputStream(file);
output = new FileOutputStream(newFile);
Cipher cipher = Cipher.getInstance("DES");
cipher.init(Cipher.ENCRYPT_MODE, mySecretKey);
byte[] buf = new byte[1024];
count = input.read(buf);
while (count >= 0) {
output.write(cipher.update(buf, 0, count)); // HERE I WAS DOING doFinal() method
count = input.read(buf);
}
output.write(cipher.doFinal()); // AND I DID NOT HAD THIS LINE BEFORE
output.flush();
And when decrypting, with the same method, but with a Cipher init with DECRYPT_MODE
input = new FileInputStream(file);
output = new FileOutputStream(newFile);
Cipher cipher = Cipher.getInstance("DES");
cipher.init(Cipher.DECRYPT_MODE, mySecretKey);
byte[] buf = new byte[1024];
count = input.read(buf);
while (count >= 0) {
output.write(cipher.update(buf, 0, count)); // HERE I WAS DOING doFinal() method
//AND HERE WAS THE BadPaddingExceotion -- the first pass in the while structure
count = input.read(buf);
}
output.write(cipher.doFinal()); // AND I DID NOT HAD THIS LINE BEFORE
output.flush();
With the code written, I no longer have any BadPaddingException.
I may precise that this exception only appears when the original clear file length (obtained through file.length()) is bigger than the buffer. Else, we do not need to pass several times in the while structure, and we can encrypt in one pass with a doFinal() call. That justify the random character of the exception following the size of the file you try to encrypt.
I hope you had a good reading!

I guess the expression message.trim().getBytes() does not return the same bytes which are generated when you encrypted the message. Specially the trim() method could delete the bytes which were added as padding in the encrypted message.
Verify that both the returned array of the doFinal() method during the encryption and the returned array of message.trim().getBytes():
got the same number of bytes (array length)
got the same bytes in the array

KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA");
kpg.initialize(512);
KeyPair rsaKeyPair = kpg.genKeyPair();
byte[] txt = "This is a secret message.".getBytes();
System.out.println("Original clear message: " + new String(txt));
// encrypt
Cipher cipher;
try
{
cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
cipher.init(Cipher.ENCRYPT_MODE, rsaKeyPair.getPublic());
txt = cipher.doFinal(txt);
}
catch (Throwable e)
{
e.printStackTrace();
return;
}
System.out.println("Encrypted message: " + new String(txt));
// decrypt
try
{
cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
cipher.init(Cipher.DECRYPT_MODE, rsaKeyPair.getPrivate());
txt = cipher.doFinal(txt);
}
catch (Throwable e)
{
e.printStackTrace();
return;
}
System.out.println("Decrypted message: " + new String(txt));

Here is a solution I was able to piece together using a jks keystore with RSA encryption
import javax.crypto.Cipher;
import javax.xml.bind.DatatypeConverter;
import java.security.Key;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.KeyStore;
import java.security.cert.Certificate;
public class Main {
public static void main(String[] args) {
byte[] txt = "This is a secret message for your own eyes only".getBytes();
byte[] encText;
try{
// Load the keystore
KeyStore ks = KeyStore.getInstance(KeyStore.getDefaultType());
char[] password = "keystorePassword".toCharArray();
java.io.FileInputStream fis = new java.io.FileInputStream("/path/to/keystore/myKeyStore.jks");
ks.load(fis, password);
fis.close();
Key rsakey = ks.getKey("mykeyalias", password);
Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
// Encrypt
Certificate cert = ks.getCertificate("mykeyalias");
try
{
cipher.init(Cipher.ENCRYPT_MODE, cert.getPublicKey());
encText = cipher.doFinal(txt);
System.out.println(encText.toString());
}
catch (Throwable e)
{
e.printStackTrace();
return;
}
// Decrypt
cipher.init(Cipher.DECRYPT_MODE, rsakey);
String decrypted = new String(cipher.doFinal(encText));
System.out.println(decrypted);
} catch (Exception e) {
System.out.println("error" + e);
}
}