Develop Reference

Java read a encrypted string and decode it

I am trying to encrypt a string with a user defined password and then decode it with the string again.
My code:
SecurityManager.java
package de.example.org;
import javax.crypto.*;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.SecretKeySpec;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.security.spec.InvalidKeySpecException;
import java.util.Base64;
public class SecurityManager {
private static final String ALGORITHM = "AES";
private static final String TRANSFORMATION = "AES/ECB/PKCS5Padding";
private static final SecureRandom secureRandom = new SecureRandom();
private static final Base64.Encoder base64Encoder = Base64.getUrlEncoder();
private static final SecretKeyFactory factory;
static {
try {
factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
} catch (NoSuchAlgorithmException e) {
throw new RuntimeException(e);
}
}
private static PBEKeySpec generatePBEKeySpec(String password) {
return new PBEKeySpec(password.toCharArray(), generateRandomString(16).getBytes(), 65536, 128);
}
public static String generateRandomString(int length) {
byte[] randomBytes = new byte[length];
secureRandom.nextBytes(randomBytes);
return base64Encoder.encodeToString(randomBytes);
}
public static String generateEncryptedKey(String password) throws InvalidKeySpecException, NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
SecretKey secretKey = factory.generateSecret(generatePBEKeySpec(password));
byte[] encodedKey = secretKey.getEncoded();
// Convert the secretKey to a SecretKeySpec
Key secretKeySpec = new SecretKeySpec(encodedKey, ALGORITHM);
// Encrypt the original string
Cipher cipher = Cipher.getInstance(TRANSFORMATION);
cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec);
String random = generateRandomString(128);
System.out.println(random);
byte[] encryptedBytes = cipher.doFinal(random.getBytes());
return new String(encryptedBytes);
}
public static String decryptKey(String encryptedKey, String password) throws InvalidKeySpecException, NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
SecretKey secretKey = factory.generateSecret(generatePBEKeySpec(password));
byte[] encodedKey = secretKey.getEncoded();
// Convert the secretKey to a SecretKeySpec
Key secretKeySpec = new SecretKeySpec(encodedKey, ALGORITHM);
// Decrypt the encrypted string
Cipher cipher = Cipher.getInstance(TRANSFORMATION);
cipher.init(Cipher.DECRYPT_MODE, secretKeySpec);
byte[] decryptedBytes = cipher.doFinal(encryptedKey.getBytes());
return new String(decryptedBytes);
}
}
Executing the function in main:
String encrypted = SecurityManager.generateEncryptedKey("123");
String decrypted = SecurityManager.decryptKey(encrypted, "123");
System.out.println(decrypted);
Error:
Exception in thread "main" javax.crypto.IllegalBlockSizeException: Input length must be multiple of 16 when decrypting with padded cipher
at java.base/com.sun.crypto.provider.CipherCore.prepareInputBuffer(CipherCore.java:887)
at java.base/com.sun.crypto.provider.CipherCore.doFinal(CipherCore.java:729)
at java.base/com.sun.crypto.provider.AESCipher.engineDoFinal(AESCipher.java:434)
at java.base/javax.crypto.Cipher.doFinal(Cipher.java:2206)
at de.example.org.SecurityManager.decryptKey(SecurityManager.java:66)
at de.example.org.main.Main.main(Main.java:11)
I have been sitting on this for hours now, and with bytes I can encrypt it. But since I want to store the encrypted string, so it's still available after a restart, storing the bytes in a file would be less secure AFAIK.

My code wasn't actually able to decrypt. This code does the job:
package de.alexx1.birthdaynotf.helper;
import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.SecretKeySpec;
import java.security.Key;
import java.security.SecureRandom;
import java.security.spec.KeySpec;
import java.util.Arrays;
import java.util.Base64;
public class SecurityManager {
private static final String ALGORITHM = "AES/CBC/PKCS5Padding";
private static final String CHARSET = "UTF-8";
private static final int KEY_SIZE = 128;
private static final int ITERATIONS = 65536;
private static final int SALT_LENGTH = 16;
private static final SecureRandom secureRandom = new SecureRandom();
private static final Base64.Encoder base64Encoder = Base64.getEncoder();
public static String generateRandomString(int length) {
byte[] randomBytes = new byte[length];
secureRandom.nextBytes(randomBytes);
return base64Encoder.encodeToString(randomBytes);
}
public static String encrypt(String plainText, String password) throws Exception {
byte[] salt = generateSalt();
SecretKey secretKey = generateSecretKey(password, salt);
byte[] keyBytes = secretKey.getEncoded();
Key key = new SecretKeySpec(keyBytes, "AES");
Cipher cipher = Cipher.getInstance(ALGORITHM);
cipher.init(Cipher.ENCRYPT_MODE, key);
byte[] encryptedBytes = cipher.doFinal(plainText.getBytes(CHARSET));
byte[] iv = cipher.getIV();
byte[] encryptedText = new byte[salt.length + iv.length + encryptedBytes.length];
System.arraycopy(salt, 0, encryptedText, 0, salt.length);
System.arraycopy(iv, 0, encryptedText, salt.length, iv.length);
System.arraycopy(encryptedBytes, 0, encryptedText, salt.length + iv.length, encryptedBytes.length);
return Base64.getEncoder().encodeToString(encryptedText);
}
public static String decrypt(String encryptedText, String password) throws Exception {
byte[] encryptedTextBytes = Base64.getDecoder().decode(encryptedText.getBytes(CHARSET));
byte[] salt = Arrays.copyOfRange(encryptedTextBytes, 0, SALT_LENGTH);
byte[] iv = Arrays.copyOfRange(encryptedTextBytes, SALT_LENGTH, SALT_LENGTH + 16);
byte[] cipherText = Arrays.copyOfRange(encryptedTextBytes, SALT_LENGTH + 16, encryptedTextBytes.length);
SecretKey secretKey = generateSecretKey(password, salt);
Key key = new SecretKeySpec(secretKey.getEncoded(), "AES");
Cipher cipher = Cipher.getInstance(ALGORITHM);
cipher.init(Cipher.DECRYPT_MODE, key, new IvParameterSpec(iv));
byte[] decryptedBytes = cipher.doFinal(cipherText);
return new String(decryptedBytes, CHARSET);
}
private static SecretKey generateSecretKey(String password, byte[] salt) throws Exception {
SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA256");
KeySpec spec = new PBEKeySpec(password.toCharArray(), salt, ITERATIONS, KEY_SIZE);
return factory.generateSecret(spec);
}
private static byte[] generateSalt() {
byte[] salt = new byte[SALT_LENGTH];
secureRandom.nextBytes(salt);
return salt;
}
}

AES 256 Text Encryption returning different values

I'm trying to replicate an encryption method based on another C# method that I found.
The C# Encryption method EncryptText(word, password) call to another method AES_Encrypt(byte[] bytesToBeEncrypted, byte[] passwordBytes) to encrypt plain text:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;
using System.Security.Cryptography;
using System.IO;
using System.Text;
namespace Rextester
{
public class Program
{
public static void Main(string[] args)
{
var f = EncryptText("763059", "515t3ma5m15B4d35");//(word, password)
Console.WriteLine(f);
}
public static byte[] AES_Encrypt(byte[] bytesToBeEncrypted, byte[] passwordBytes)
{
byte[] encryptedBytes = null;
byte[] saltBytes = new byte[] { 1, 2, 3, 4, 5, 6, 7, 8 };
using (MemoryStream ms = new MemoryStream())
{
using (RijndaelManaged AES = new RijndaelManaged())
{
AES.KeySize = 256;
AES.BlockSize = 128;
var key = new Rfc2898DeriveBytes(passwordBytes, saltBytes, 1000);
AES.Key = key.GetBytes(AES.KeySize / 8);
AES.IV = key.GetBytes(AES.BlockSize / 8);
AES.Mode = CipherMode.CBC;
using (var cs = new CryptoStream(ms, AES.CreateEncryptor(), CryptoStreamMode.Write))
{
cs.Write(bytesToBeEncrypted, 0, bytesToBeEncrypted.Length);
cs.Close();
}
encryptedBytes = ms.ToArray();
}
}
return encryptedBytes;
}
public static string EncryptText(string input, string password)
{
byte[] bytesToBeEncrypted = Encoding.UTF8.GetBytes(input);
byte[] passwordBytes = Encoding.UTF8.GetBytes(password);
passwordBytes = SHA256.Create().ComputeHash(passwordBytes);
byte[] bytesEncrypted = AES_Encrypt(bytesToBeEncrypted, passwordBytes);
string result = Convert.ToBase64String(bytesEncrypted);
return result;
}
}
}
Using word 763059 and password 515t3ma5m15B4d35, the output is the following:
3cHrXxxL1Djv0K2xW4HuCg==
UPDATE:
Now, I created a Java Class main where I'm trying to replicate previous code:
public class main {
final static String PASSWORD = "515t3ma5m15B4d35";
final static byte[] SALT = new byte[]{1, 2, 3, 4, 5, 6, 7, 8};
final static int KEY_SIZE = 256;
final static int BLOCK_SIZE = 128;
final static int ITERATIONS = 1000;
public static void main(String[] args) {
System.out.println(encryptText("763059", PASSWORD));
}
public static String encryptText(String word, String password) {
try {
MessageDigest md = MessageDigest.getInstance("SHA-256");
md.update(password.getBytes("UTF-8"));
password = new String(md.digest(), "UTF-8");
SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
KeySpec spec = new PBEKeySpec(password.toCharArray(), SALT, ITERATIONS, KEY_SIZE);
SecretKey tmp = factory.generateSecret(spec);
SecretKeySpec skey = new SecretKeySpec(tmp.getEncoded(), "AES");
byte[] iv = new byte[BLOCK_SIZE / 8];
IvParameterSpec ivspec = new IvParameterSpec(iv);
Cipher ci = Cipher.getInstance("AES/CBC/PKCS5Padding");
ci.init(Cipher.ENCRYPT_MODE, skey, ivspec);
byte[] result = ci.doFinal(word.getBytes("UTF-8"));
return DatatypeConverter.printBase64Binary(result);
} catch (NoSuchAlgorithmException | UnsupportedEncodingException | IllegalBlockSizeException | BadPaddingException | InvalidKeyException | InvalidAlgorithmParameterException | NoSuchPaddingException | InvalidKeySpecException ex) {
return null;
}
}
}
UPDATE:
I read about using 256 bits keys in Java, and I found that I need to add Java Cryptography Extensions to allow 256 keys (Because I'm working with JDK7).
Then I added the libreries to the project, also I change the line:
KeySpec spec = new PBEKeySpec(password.toCharArray(), SALT, ITERATIONS, KEY_SIZE);
With the Key Value:
final static int KEY_SIZE = 256;
Now the output is the following:
J1xbKOjIeXbQ9njH+67RNw==
I still can't achieve my goal. Any Suggestion?

Finally I decided to use the BouncyCastle API to use the functionality of RijndaelEngine, as well as to generate the 256-bit key with PKCS5S2ParametersGenerator.
I created the RijndaelEncryption class to be able to perform the encryption as in the C# code:
public class RijndaelEncryption {
public String encryptString(String word, String password, byte[] salt, int iterations, int keySize, int blockSize) {
try {
byte[] pswd = sha256String(password, "UTF-8");
PKCS5S2ParametersGenerator key = keyGeneration(pswd, salt, iterations);
ParametersWithIV iv = generateIV(key, keySize, blockSize);
BufferedBlockCipher cipher = getCipher(true, iv);
byte[] inputText = word.getBytes("UTF-8");
byte[] newData = new byte[cipher.getOutputSize(inputText.length)];
int l = cipher.processBytes(inputText, 0, inputText.length, newData, 0);
cipher.doFinal(newData, l);
return new String(Base64.encode(newData), "UTF-8");
} catch (UnsupportedEncodingException | IllegalStateException | DataLengthException | InvalidCipherTextException e) {
return null;
}
}
public BufferedBlockCipher getCipher(boolean encrypt, ParametersWithIV iv) {
RijndaelEngine rijndael = new RijndaelEngine();
BufferedBlockCipher cipher = new PaddedBufferedBlockCipher(new CBCBlockCipher(rijndael));
cipher.init(encrypt, iv);
return cipher;
}
public ParametersWithIV generateIV(PKCS5S2ParametersGenerator key, int keySize, int blockSize) {
try {
ParametersWithIV iv = null;
iv = ((ParametersWithIV) key.generateDerivedParameters(keySize, blockSize));
return iv;
} catch (Exception e) {
return null;
}
}
public PKCS5S2ParametersGenerator keyGeneration(byte[] password, byte[] salt, int iterations) {
try {
PKCS5S2ParametersGenerator key = new PKCS5S2ParametersGenerator();
key.init(password, salt, iterations);
return key;
} catch (Exception e) {
return null;
}
}
public byte[] sha256String(String password, Charset charset) {
try {
MessageDigest md = MessageDigest.getInstance("SHA-256");
md.update(password.getBytes(charset));
return md.digest();
} catch (NoSuchAlgorithmException ex) {
return null;
}
}
public byte[] sha256String(String password, String charset) {
try {
MessageDigest md = MessageDigest.getInstance("SHA-256");
md.update(password.getBytes(charset));
return md.digest();
} catch (NoSuchAlgorithmException | UnsupportedEncodingException ex) {
return null;
}
}
}
And I tested in main method:
public static void main(String[] args) {
RijndaelEncryption s = new RijndaelEncryption();
byte[] salt = new byte[]{1, 2, 3, 4, 5, 6, 7, 8};
String encryptStr = s.encryptString("763059", "515t3ma5m15B4d35", salt, 1000, 256, 128);
System.out.println("Encryptation: " + encryptStr);
}
To get:
Encryptation: 3cHrXxxL1Djv0K2xW4HuCg==

I am not any C# expert, but there are a few things to be checked:
Reading the documentation about Rfc2898DeriveBytes I see the function is using SHA1 hash, so try you may try to use PBKDF2WithHmacSHA1
On both instances (Rfc2898DeriveBytes, PBEKeySpec) you should make sure you the key size is the same (256 bit), it is surely wrong in your Java code
You may try to encode and print the keys to really make sure they are the same.
I need to add Java Cryptography Extensions to allow 256 keys.
Depends on your JVM version. I believe Oracle JDK since v. 1.8u162 by default contains the Unlimited Strength JCE policy. If you take any current JRE version, you should be ok
Additional: you are using (static) zero array IV, which is not secure

I have an answer for the original question. For future reference without bouncycastle.
You had a few problems.
Key size needed to be 256 + 128 (blocksize as well)
C# and Java byte[] don't act the same because java bytes are always signed which messes with the encryption of the password.
Both of these pieces of code give as output:
xD4R/yvV2tHajUS9p4kqJg==
C# code:
using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;
namespace tryencryption
{
class Program
{
static void Main(string[] args)
{
var f = EncryptText("yme", "515t3ma5m15B4d35");//(word, password)
Console.WriteLine(f);
Console.ReadKey();
}
public static byte[] AES_Encrypt(byte[] bytesToBeEncrypted, string passwordString)
{
byte[] encryptedBytes = null;
byte[] salt = new byte[] { (byte)0x49, (byte)0x64, (byte)0x76, (byte)0x65, (byte)0x64, (byte)0x65, (byte)0x76, (byte)0x61, (byte)0x6e, (byte)0x20, (byte)0x4d, (byte)0x65, (byte)0x76 };
using (MemoryStream ms = new MemoryStream())
{
using (RijndaelManaged AES = new RijndaelManaged())
{
AES.KeySize = 256;
AES.BlockSize = 128;
var key = new Rfc2898DeriveBytes(passwordString, salt, 1000);
AES.Key = key.GetBytes(AES.KeySize / 8);
AES.IV = key.GetBytes(AES.BlockSize / 8);
AES.Mode = CipherMode.CBC;
using (var cs = new CryptoStream(ms, AES.CreateEncryptor(), CryptoStreamMode.Write))
{
cs.Write(bytesToBeEncrypted, 0, bytesToBeEncrypted.Length);
cs.Close();
}
encryptedBytes = ms.ToArray();
}
}
return encryptedBytes;
}
public static string EncryptText(string input, string password)
{
byte[] bytesToBeEncrypted = Encoding.Unicode.GetBytes(input);
byte[] bytesEncrypted = AES_Encrypt(bytesToBeEncrypted, password);
string result = Convert.ToBase64String(bytesEncrypted);
return result;
}
}
}
Java code (this was from an android project bcs that's my usecase but should work everywhere):
package com.example.myapplication;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Base64;
import java.nio.charset.StandardCharsets;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.spec.AlgorithmParameterSpec;
import java.security.spec.InvalidKeySpecException;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.SecretKeySpec;
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
String result = encrypt("yme", "515t3ma5m15B4d35");
}
private static String encrypt(String word, String password) {
byte[] salt = new byte[] { (byte)0x49, (byte)0x64, (byte)0x76, (byte)0x65, (byte)0x64, (byte)0x65, (byte)0x76, (byte)0x61, (byte)0x6e, (byte)0x20, (byte)0x4d, (byte)0x65, (byte)0x76};
try {
SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
PBEKeySpec pbeKeySpec = new PBEKeySpec(password.toCharArray(), salt, 1000, 256 + 128);
Key secretKey = factory.generateSecret(pbeKeySpec);
byte[] test = secretKey.getEncoded();
byte[] key = new byte[32];
byte[] iv = new byte[16];
System.arraycopy(secretKey.getEncoded(), 0, key, 0, 32);
System.arraycopy(secretKey.getEncoded(), 32, iv, 0, 16);
SecretKeySpec secret = new SecretKeySpec(key, "AES");
AlgorithmParameterSpec ivSpec = new IvParameterSpec(iv);
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
cipher.init(Cipher.ENCRYPT_MODE, secret, ivSpec);
//Realise Im using UTF16 here! Maybe you need UTF8
byte[] plaintextintobytes =word.getBytes(StandardCharsets.UTF_16LE);
byte[] encrypted = cipher.doFinal(plaintextintobytes);
String encryptedInformation = Base64.encodeToString(encrypted, Base64.NO_WRAP);
return encryptedInformation;
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
} catch (InvalidKeySpecException e) {
e.printStackTrace();
} catch (NoSuchPaddingException e) {
e.printStackTrace();
} catch (InvalidKeyException e) {
e.printStackTrace();
} catch (InvalidAlgorithmParameterException e) {
e.printStackTrace();
} catch (IllegalBlockSizeException e) {
e.printStackTrace();
} catch (BadPaddingException e) {
e.printStackTrace();
}
return "";
}
}

AES Encryption IV's

I am using this below (E.1) for my application, there is obviously a huge glaring security hole in this that I recognize and understand. I have grown interested in encryption and want to understand it better, I need to generate a random key along with an IV but am unsure how to do so properly Can someone explain to me whom is familiar with AES encryption how this works (IV & KEY) So I am better able to understand in the future and can apply my knowledge, essentially I just want to make the code more secure, thank you.
(E.1)
byte[] key = "mykey".getBytes("UTF-8");
private byte[] getKeyBytes(final byte[] key) throws Exception {
byte[] keyBytes = new byte[16];
System.arraycopy(key, 0, keyBytes, 0, Math.min(key.length, keyBytes.length));
return keyBytes;
}
public Cipher getCipherEncrypt(final byte[] key) throws Exception {
byte[] keyBytes = getKeyBytes(key);
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
SecretKeySpec secretKeySpec = new SecretKeySpec(keyBytes, "AES");
IvParameterSpec ivParameterSpec = new IvParameterSpec(keyBytes);
cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec, ivParameterSpec);
return cipher;
}
public void encrypt(File in, File output, byte[] key) throws Exception {
Cipher cipher = getCipherEncrypt(key);
FileOutputStream fos = null;
CipherOutputStream cos = null;
FileInputStream fis = null;
try {
fis = new FileInputStream(in);
fos = new FileOutputStream(output);
cos = new CipherOutputStream(fos, cipher);
byte[] data = new byte[1024];
int read = fis.read(data);
while (read != -1) {
cos.write(data, 0, read);
read = fis.read(data);
System.out.println(new String(data, "UTF-8").trim());
}
cos.flush();
} finally {
System.out.println("performed encrypt method now closing streams:\n" + output.toString());
cos.close();
fos.close();
fis.close();
}
}
public void watchMeEncrypt(){
encrypt(file, new File ("example.txt),key);

An AES key simply consists of random bytes. For CBC mode the IV mode should also be randomized (at least to an attacker). So in general you can simply use a SecureRandom instance to create the key and IV. The IV can then be included with the ciphertext; usually it is simply put in front of it.
With Java it is better to use a KeyGenerator though. If you look at the implementation of it in the SUN provider it will probably amount to the same thing. However using a KeyGenerator is more compatible with various kinds of keys and providers. It may well be that it is a requirement for generating keys in e.g. smart cards and HSM's.
So lets show a class with three simple methods:
package nl.owlstead.stackoverflow;
import static java.nio.charset.StandardCharsets.UTF_8;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.security.NoSuchAlgorithmException;
import java.security.Provider;
import java.security.SecureRandom;
import java.util.Optional;
import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.CipherOutputStream;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.IvParameterSpec;
public class CreateKeyAndIVForAES_CBC {
public static SecretKey createKey(final String algorithm, final int keysize, final Optional<Provider> provider, final Optional<SecureRandom> rng) throws NoSuchAlgorithmException {
final KeyGenerator keyGenerator;
if (provider.isPresent()) {
keyGenerator = KeyGenerator.getInstance(algorithm, provider.get());
} else {
keyGenerator = KeyGenerator.getInstance(algorithm);
}
if (rng.isPresent()) {
keyGenerator.init(keysize, rng.get());
} else {
// not really needed for the Sun provider which handles null OK
keyGenerator.init(keysize);
}
return keyGenerator.generateKey();
}
public static IvParameterSpec createIV(final int ivSizeBytes, final Optional<SecureRandom> rng) {
final byte[] iv = new byte[ivSizeBytes];
final SecureRandom theRNG = rng.orElse(new SecureRandom());
theRNG.nextBytes(iv);
return new IvParameterSpec(iv);
}
public static IvParameterSpec readIV(final int ivSizeBytes, final InputStream is) throws IOException {
final byte[] iv = new byte[ivSizeBytes];
int offset = 0;
while (offset < ivSizeBytes) {
final int read = is.read(iv, offset, ivSizeBytes - offset);
if (read == -1) {
throw new IOException("Too few bytes for IV in input stream");
}
offset += read;
}
return new IvParameterSpec(iv);
}
public static void main(String[] args) throws Exception {
final SecureRandom rng = new SecureRandom();
// you somehow need to distribute this key
final SecretKey aesKey = createKey("AES", 128, Optional.empty(), Optional.of(rng));
final byte[] plaintext = "owlstead".getBytes(UTF_8);
final byte[] ciphertext;
{
final ByteArrayOutputStream baos = new ByteArrayOutputStream();
final Cipher aesCBC = Cipher.getInstance("AES/CBC/PKCS5Padding");
final IvParameterSpec ivForCBC = createIV(aesCBC.getBlockSize(), Optional.of(rng));
aesCBC.init(Cipher.ENCRYPT_MODE, aesKey, ivForCBC);
baos.write(ivForCBC.getIV());
try (final CipherOutputStream cos = new CipherOutputStream(baos, aesCBC)) {
cos.write(plaintext);
}
ciphertext = baos.toByteArray();
}
final byte[] decrypted;
{
final ByteArrayInputStream bais = new ByteArrayInputStream(ciphertext);
final Cipher aesCBC = Cipher.getInstance("AES/CBC/PKCS5Padding");
final IvParameterSpec ivForCBC = readIV(aesCBC.getBlockSize(), bais);
aesCBC.init(Cipher.DECRYPT_MODE, aesKey, ivForCBC);
final byte[] buf = new byte[1_024];
try (final CipherInputStream cis = new CipherInputStream(bais, aesCBC);
final ByteArrayOutputStream baos = new ByteArrayOutputStream()) {
int read;
while ((read = cis.read(buf)) != -1) {
baos.write(buf, 0, read);
}
decrypted = baos.toByteArray();
}
}
System.out.println(new String(decrypted, UTF_8));
}
}
Note that you may not always want to generate and distribute an AES key "out-of-band". Here are a few other methods of generating a key (part #2 onwards). You may also want to take a look at more advanced exception handling for the cryptographic operation.

How to decrypt Whatsapp Database File?

I was trying to decrypt Whatsapp database file (msgstore.db.crypt) with java.
I found some python code and tried to do same thing with java. Probably its not that hard thing to do but I had some problems with handling decryption key.
But finally did it. So I wanted to share the code for people who need it.

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.spec.SecretKeySpec;
import javax.xml.bind.DatatypeConverter;
public class Crypto {
public FileInputStream mIn;
public FileOutputStream mOut;
public Crypto(String fileIn, String fileOut) {
try {
mIn = new FileInputStream(new File(fileIn));
mOut = new FileOutputStream(new File(fileOut));
decryptAES(mIn, mOut);
} catch (Exception e) {
e.printStackTrace();
}
}
public static void decryptAES(InputStream in, FileOutputStream out) throws Exception {
final String string = "346a23652a46392b4d73257c67317e352e3372482177652c";
byte[] hexAsBytes = DatatypeConverter.parseHexBinary(string);
SecretKeySpec keySpec = new SecretKeySpec(hexAsBytes, "AES");
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.DECRYPT_MODE, keySpec);
in = new CipherInputStream(in, cipher);
byte[] buffer = new byte[24];
int bytesRead;
while ((bytesRead = in.read(buffer)) != -1)
{
out.write(buffer, 0, bytesRead);
}
}
public static void main(String[] args){
Crypto c = new Crypto("C:\\msgstore.db.crypt", "D:\\WhatsappDb");
System.out.println("Decrypting Done");
}
}

An updated answer for .crypt12 files:
These are compressed, and then encrypted using AES in GCM mode
Here is some python code showing how:
"""
Example how to decrypt whatsapp msgstore backups with extension .crypt12.
Author: Willem Hengeveld <itsme#xs4all.nl>
"""
from Crypto.Cipher import AES
import zlib
import sys
datafile = keyfile = None
if len(sys.argv)==1:
print("Usage: decrypt12.py <keyfile> <msgstore.db.crypt12>")
print(" the key file is commonly found in /data/data/com.whatsapp/files/key")
print(" the crypt file is commonly found in the directory: /data/media/0/WhatsApp/Databases/")
exit(1)
for arg in sys.argv[1:]:
if arg.find('crypt12')>0:
datafile = arg
elif arg.find('key')>0:
keyfile = arg
else:
print("unknown arg", arg)
with open(keyfile, "rb") as fh:
keydata = fh.read()
key = keydata[126:]
with open(datafile, "rb") as fh:
filedata = fh.read()
iv = filedata[51:67]
aes = AES.new(key, mode=AES.MODE_GCM, nonce=iv)
with open("msg-decrypted.db", "wb") as fh:
fh.write(zlib.decompress(aes.decrypt(filedata[67:-20])))

here is an pure java routine for .db.crypt12 without bouncycastle, but only JDK.
public class Crypt12 {
public static void main(final String[] args) {
final String c12File = "1/msgstore.db.crypt12"; // input file
final String decryptedDbFile = "1/msgstore.db"; // sqlite3 db output file
final String keyFile = "1/key";
try {
final byte[] key; try(FileInputStream s = new FileInputStream(keyFile)) { key = s.readAllBytes(); }
final byte[] buf; try(FileInputStream s = new FileInputStream(c12File)) { buf = s.readAllBytes(); }
if(!Arrays.equals(key, 27, 78, buf, 0, 51)) { System.out.println("Wrong Key-File"); return; }
final int available = buf.length - 67 - 20; // 67 Byte Header + 20 byte footer
final Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
final GCMParameterSpec iv = new GCMParameterSpec(128, buf, 51, 16);
cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(key, 126, 32, "AES"), iv);
final int zipLen = cipher.doFinal(buf, 67, available, buf, 0);
final Inflater unzip = new Inflater(false);
try(FileOutputStream s = new FileOutputStream(decryptedDbFile)) {
unzip.setInput(buf, 0, zipLen);
final byte[] b = new byte[1024];
while(!unzip.needsInput()) {
final int l = unzip.inflate(b, 0, b.length);
if(l > 0) s.write(b, 0, l);
}
}
} catch (final Exception e) {
e.printStackTrace(System.out);
}
}
}

How to use 3DES algorithm on Android?

On the server side, the encyption/decryption of the password field is done in C#.
Now, i need to implement same functionality in my android application. So, i followed this tutorial: http://ttux.net/post/3des-java-encrypter-des-java-encryption/ as below:
import java.security.MessageDigest;
import java.security.spec.KeySpec;
import java.util.Arrays;
import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESedeKeySpec;
import javax.crypto.spec.IvParameterSpec;
import org.apache.commons.codec.binary.Base64;
public class Encrypter {
private KeySpec keySpec;
private SecretKey key;
private IvParameterSpec iv;
public Encrypter(String keyString, String ivString) {
try {
final MessageDigest md = MessageDigest.getInstance("md5");
final byte[] digestOfPassword = md.digest(Base64.decodeBase64(keyString.getBytes("utf-8")));
final byte[] keyBytes = Arrays.copyOf(digestOfPassword, 24);
for (int j = 0, k = 16; j < 8;) {
keyBytes[k++] = keyBytes[j++];
}
keySpec = new DESedeKeySpec(keyBytes);
key = SecretKeyFactory.getInstance("DESede").generateSecret(keySpec);
iv = new IvParameterSpec(ivString.getBytes());
} catch(Exception e) {
e.printStackTrace();
}
}
public String encrypt(String value) {
try {
Cipher ecipher = Cipher.getInstance("DESede/CBC/PKCS5Padding","SunJCE");
ecipher.init(Cipher.ENCRYPT_MODE, key, iv);
if(value==null)
return null;
// Encode the string into bytes using utf-8
byte[] utf8 = value.getBytes("UTF8");
// Encrypt
byte[] enc = ecipher.doFinal(utf8);
// Encode bytes to base64 to get a string
return new String(Base64.encodeBase64(enc),"UTF-8");
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
public String decrypt(String value) {
try {
Cipher dcipher = Cipher.getInstance("DESede/CBC/PKCS5Padding","SunJCE");
dcipher.init(Cipher.DECRYPT_MODE, key, iv);
if(value==null)
return null;
// Decode base64 to get bytes
byte[] dec = Base64.decodeBase64(value.getBytes());
// Decrypt
byte[] utf8 = dcipher.doFinal(dec);
// Decode using utf-8
return new String(utf8, "UTF8");
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
}
but i dont know what values i need to provide for KeyValue and ivValue for the above code. Please help me...

Use this code to encrypt your string
import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import android.util.Base64;
//string encryption
public class EncryptionHelper {
// Encrypts string and encode in Base64
public static String encryptText(String plainText) throws Exception {
// ---- Use specified 3DES key and IV from other source --------------
byte[] plaintext = plainText.getBytes();//input
byte[] tdesKeyData = Constants.getKey().getBytes();// your encryption key
byte[] myIV = Constants.getInitializationVector().getBytes();// initialization vector
Cipher c3des = Cipher.getInstance("DESede/CBC/PKCS5Padding");
SecretKeySpec myKey = new SecretKeySpec(tdesKeyData, "DESede");
IvParameterSpec ivspec = new IvParameterSpec(myIV);
c3des.init(Cipher.ENCRYPT_MODE, myKey, ivspec);
byte[] cipherText = c3des.doFinal(plaintext);
String encryptedString = Base64.encodeToString(cipherText,
Base64.DEFAULT);
// return Base64Coder.encodeString(new String(cipherText));
return encryptedString;
}
}
This is how you can encrypt the string
String encryptedPassword = EncryptionHelper.encryptText(edtText.getText().toString());
EDIT
Code for Constants.java
Class Constants {
private final String initializationVector = "INITALIZATION_VECTOR";
private final String ecnryptionKey = "ENCRYPTION_KEY";
public static String getInitializationVector() {
return initializationVector;
}
public static String getKey() {
return ecnryptionKey;
}
}

Triple DES is called "DESede" (DES using single DES Encrypt, Decrypt, Encrypt for encryption) in both Java and Android runtimes. So it is build in functionality which can be access through the Cipher class. It also lists the available algorithms. For triple DES you could use "DESede/CBC/PKCS5Padding"`. Don't forget to supply it a random IV of 8 bytes.
Triple DES should only be used for backwards compatibility. If you decide to use it at least supply it 24 bytes of key material, otherwise there is a chance that your ciphertext can be cracked. For a more modern approach use AES, preferably in an authenticated mode such as GCM ("AES/GCM/NoPadding"). Note that GCM requires a unique nonce of 12 bytes.