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Java AES GCM AEAD Tag mismatch

Im trying to write a program to encrypt any type of file. I had my encryption classes already done, when I noticed (at first it worked) that I am getting an AEADBadTagException whenever I try to decrypt any of my files.
Here is my encryption/decryption class:
class Encryptor {
private static final String algorithm = "AES/GCM/NoPadding";
private final int tagLengthBit = 128; // must be one of {128, 120, 112, 104, 96}
private final int ivLengthByte = 12;
private final int saltLengthByte = 64;
protected final Charset UTF_8 = StandardCharsets.UTF_8;
private CryptoUtils crypto = new CryptoUtils();
// return a base64 encoded AES encrypted text
/**
*
* #param pText to encrypt
* #param password password for encryption
* #return encoded pText
* #throws Exception
*/
protected byte[] encrypt(byte[] pText, char[] password) throws Exception {
// 64 bytes salt
byte[] salt = crypto.getRandomNonce(saltLengthByte);
// GCM recommended 12 bytes iv?
byte[] iv = crypto.getRandomNonce(ivLengthByte);
// secret key from password
SecretKey aesKeyFromPassword = crypto.getAESKeyFromPassword(password, salt);
Cipher cipher = Cipher.getInstance(algorithm);
// ASE-GCM needs GCMParameterSpec
cipher.init(Cipher.ENCRYPT_MODE, aesKeyFromPassword, new GCMParameterSpec(tagLengthBit, iv));
byte[] cipherText = cipher.doFinal(pText);
// prefix IV and Salt to cipher text
byte[] cipherTextWithIvSalt = ByteBuffer.allocate(iv.length + salt.length + cipherText.length).put(iv).put(salt)
.put(cipherText).array();
Main.clearArray(password, null);
Main.clearArray(null, salt);
Main.clearArray(null, iv);
Main.clearArray(null, cipherText);
aesKeyFromPassword = null;
cipher = null;
try {
return cipherTextWithIvSalt;
} finally {
Main.clearArray(null, cipherTextWithIvSalt);
}
}
// für Files
protected byte[] decrypt(byte[] encryptedText, char[] password)
throws InvalidKeyException, InvalidAlgorithmParameterException, NoSuchAlgorithmException,
NoSuchPaddingException, InvalidKeySpecException, IllegalBlockSizeException, BadPaddingException {
// get back the iv and salt from the cipher text
ByteBuffer bb = ByteBuffer.wrap(encryptedText);
byte[] iv = new byte[ivLengthByte];
bb.get(iv);
byte[] salt = new byte[saltLengthByte];
bb.get(salt);
byte[] cipherText = new byte[bb.remaining()];
bb.get(cipherText);
// get back the aes key from the same password and salt
SecretKey aesKeyFromPassword;
aesKeyFromPassword = crypto.getAESKeyFromPassword(password, salt);
Cipher cipher;
cipher = Cipher.getInstance(algorithm);
cipher.init(Cipher.DECRYPT_MODE, aesKeyFromPassword, new GCMParameterSpec(tagLengthBit, iv));
byte[] plainText = cipher.doFinal(cipherText);
Main.clearArray(password, null);
Main.clearArray(null, iv);
Main.clearArray(null, salt);
Main.clearArray(null, cipherText);
aesKeyFromPassword = null;
cipher = null;
bb = null;
try {
return plainText;
} finally {
Main.clearArray(null, plainText);
}
}
protected void encryptFile(String file, char[] pw) throws Exception {
Path pathToFile = Paths.get(file);
byte[] fileCont = Files.readAllBytes(pathToFile);
byte[] encrypted = encrypt(fileCont, pw);
Files.write(pathToFile, encrypted);
Main.clearArray(pw, null);
Main.clearArray(null, fileCont);
Main.clearArray(null, encrypted);
}
protected void decryptFile(String file, char[] pw)
throws IOException, InvalidKeyException, InvalidAlgorithmParameterException, NoSuchAlgorithmException,
NoSuchPaddingException, InvalidKeySpecException, IllegalBlockSizeException, BadPaddingException {
Path pathToFile = Paths.get(file);
byte[] fileCont = Files.readAllBytes(pathToFile);
byte[] decrypted = decrypt(fileCont, pw);
Files.write(pathToFile, decrypted);
Main.clearArray(pw, null);
Main.clearArray(null, fileCont);
Main.clearArray(null, decrypted);
}
}
The corresponding CryptoUtils class:
class CryptoUtils {
protected byte[] getRandomNonce(int numBytes) {
byte[] nonce = new byte[numBytes];
new SecureRandom().nextBytes(nonce);
try {
return nonce;
} finally {
Main.clearArray(null, nonce);
}
}
// Password derived AES 256 bits secret key
protected SecretKey getAESKeyFromPassword(char[] password, byte[] salt)
throws NoSuchAlgorithmException, InvalidKeySpecException {
SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA512");
// iterationCount = 65536
// keyLength = 256
KeySpec spec = new PBEKeySpec(password, salt, 65536, 256);
SecretKey secret = new SecretKeySpec(factory.generateSecret(spec).getEncoded(), "AES");
try {
return secret;
} finally {
secret = null;
}
}
// hex representation
protected String hex(byte[] bytes) {
StringBuilder result = new StringBuilder();
for (byte b : bytes) {
result.append(String.format("%02x", b));
}
try {
return result.toString();
} finally {
result.delete(0, result.length() - 1);
}
}
// print hex with block size split
protected String hexWithBlockSize(byte[] bytes, int blockSize) {
String hex = hex(bytes);
// one hex = 2 chars
blockSize = blockSize * 2;
// better idea how to print this?
List<String> result = new ArrayList<>();
int index = 0;
while (index < hex.length()) {
result.add(hex.substring(index, Math.min(index + blockSize, hex.length())));
index += blockSize;
}
try {
return result.toString();
} finally {
result.clear();
}
}
}
The Exception occurs at byte[] plainText = cipher.doFinal(cipherText); in the decrypt method.
Im unsure if the tagLenthBit must be the ivLengthByte * 8, I did try it though and it didnt make any difference.

I'm providing my own example code for AES 256 GCM file encryption with PBKDF2 key derivation because I'm too lazy to check all parts of your code :-)
The encryption is done with CipherInput-/Outputstreams because that avoids "out of memory errors" when encrypting larger files (your code is reading the complete plaintext / ciphertext in a byte array).
Please note that the code has no exception handling, no clearing of sensitive data/variables and the encryption/decryption result is a simple "file exist" routine but I'm sure you can use it as a good basis for your program.
That's a sample output:
AES 256 GCM-mode PBKDF2 with SHA512 key derivation file encryption
result encryption: true
result decryption: true
code:
import javax.crypto.*;
import javax.crypto.spec.GCMParameterSpec;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.SecretKeySpec;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.security.*;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.KeySpec;
public class AesGcmEncryptionInlineIvPbkdf2BufferedCipherInputStreamSoExample {
public static void main(String[] args) throws NoSuchPaddingException, NoSuchAlgorithmException, IOException,
InvalidKeyException, InvalidKeySpecException, InvalidAlgorithmParameterException {
System.out.println("AES 256 GCM-mode PBKDF2 with SHA512 key derivation file encryption");
char[] password = "123456".toCharArray();
int iterations = 65536;
String uncryptedFilename = "uncrypted.txt";
String encryptedFilename = "encrypted.enc";
String decryptedFilename = "decrypted.txt";
boolean result;
result = encryptGcmFileBufferedCipherOutputStream(uncryptedFilename, encryptedFilename, password, iterations);
System.out.println("result encryption: " + result);
result = decryptGcmFileBufferedCipherInputStream(encryptedFilename, decryptedFilename, password, iterations);
System.out.println("result decryption: " + result);
}
public static boolean encryptGcmFileBufferedCipherOutputStream(String inputFilename, String outputFilename, char[] password, int iterations) throws
IOException, NoSuchPaddingException, NoSuchAlgorithmException, InvalidKeySpecException, InvalidKeyException, InvalidAlgorithmParameterException {
SecureRandom secureRandom = new SecureRandom();
byte[] salt = new byte[32];
secureRandom.nextBytes(salt);
byte[] nonce = new byte[12];
secureRandom.nextBytes(nonce);
Cipher cipher = Cipher.getInstance("AES/GCM/NOPadding");
try (FileInputStream in = new FileInputStream(inputFilename);
FileOutputStream out = new FileOutputStream(outputFilename);
CipherOutputStream encryptedOutputStream = new CipherOutputStream(out, cipher);) {
out.write(nonce);
out.write(salt);
SecretKeyFactory secretKeyFactory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA512");
KeySpec keySpec = new PBEKeySpec(password, salt, iterations, 32 * 8); // 128 - 192 - 256
byte[] key = secretKeyFactory.generateSecret(keySpec).getEncoded();
SecretKeySpec secretKeySpec = new SecretKeySpec(key, "AES");
GCMParameterSpec gcmParameterSpec = new GCMParameterSpec(16 * 8, nonce);
cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec, gcmParameterSpec);
byte[] buffer = new byte[8096];
int nread;
while ((nread = in.read(buffer)) > 0) {
encryptedOutputStream.write(buffer, 0, nread);
}
encryptedOutputStream.flush();
}
if (new File(outputFilename).exists()) {
return true;
} else {
return false;
}
}
public static boolean decryptGcmFileBufferedCipherInputStream(String inputFilename, String outputFilename, char[] password, int iterations) throws
IOException, NoSuchPaddingException, NoSuchAlgorithmException, InvalidKeySpecException, InvalidKeyException, InvalidAlgorithmParameterException {
byte[] salt = new byte[32];
byte[] nonce = new byte[12];
Cipher cipher = Cipher.getInstance("AES/GCM/NOPadding");
try (FileInputStream in = new FileInputStream(inputFilename); // i don't care about the path as all is lokal
CipherInputStream cipherInputStream = new CipherInputStream(in, cipher);
FileOutputStream out = new FileOutputStream(outputFilename)) // i don't care about the path as all is lokal
{
byte[] buffer = new byte[8192];
in.read(nonce);
in.read(salt);
SecretKeyFactory secretKeyFactory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA512");
KeySpec keySpec = new PBEKeySpec(password, salt, iterations, 32 * 8); // 128 - 192 - 256
byte[] key = secretKeyFactory.generateSecret(keySpec).getEncoded();
SecretKeySpec secretKeySpec = new SecretKeySpec(key, "AES");
GCMParameterSpec gcmParameterSpec = new GCMParameterSpec(16 * 8, nonce);
cipher.init(Cipher.DECRYPT_MODE, secretKeySpec, gcmParameterSpec);
int nread;
while ((nread = cipherInputStream.read(buffer)) > 0) {
out.write(buffer, 0, nread);
}
out.flush();
}
if (new File(outputFilename).exists()) {
return true;
} else {
return false;
}
}
}

C# encrypt to Java Decrypt

I am using a C# "encrypt" and need a Java "decrypt" method. I need help in java that i can't replicate C# decryption on java and it is not explicit Padding on C# , i don't know what use in java and my key size I think is different but I am not sure. I'm very confused.
know that i need change Java Policy , and did it ! and Change Key size JAVA to 32 bytes.
C#
using System;
using System.IO;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using Voa.Cross.Util.Extensions;
namespace Voa.Core.Safeties
{
public class Security
{
private readonly string _defaultKey = "sjkdhfjksdhf3444KDFK4nFLFGKdsnjcnj2cmkeKDIK484dmd999sksksksUUddUZ83k030394m49jdjPuWzRk8Zq2PfnpR3YrYWSq2AaUT6meeC3tr36nTVkuudKWbDyPjhUwbwXBzkUhSPKPpSRheR49em4qJWa6YHSCjKX3K93FEMnqXhYauXwjJwbHXfPWTSdxy6ebCBPyAfqk7Uz5nrRddVjZrxWNCMZYG3PbcvPWA34ekdkd454ldnvJKl";
private readonly int _divisionKey = 4;
private readonly byte[] _iv = new byte[16] {0x26, 0xdc, 0xff, 0x00, 0xad, 0xed, 0x7a, 0xee, 0xc5, 0xfe, 0x07, 0xaf, 0x4d, 0x08, 0x22, 0x3c};
private byte[] _key;
public Security() => _key = SHA256.Create().ComputeHash(Encoding.ASCII.GetBytes(_defaultKey));
public string Encrypt(string data, string key)
{
if (!string.IsNullOrEmpty(key))
{
CustomKey(key);
}
var encryptor = Aes.Create();
encryptor.Mode = CipherMode.CBC;
// Set key and IV
var aesKey = new byte[32];
Array.Copy(_key, 0, aesKey, 0, 32);
encryptor.Key = aesKey;
encryptor.IV = _iv;
var memoryStream = new MemoryStream();
var aesEncryptor = encryptor.CreateEncryptor();
var cryptoStream = new CryptoStream(memoryStream, aesEncryptor, CryptoStreamMode.Write);
var plainBytes = Encoding.ASCII.GetBytes(data);
cryptoStream.Write(plainBytes, 0, plainBytes.Length);
cryptoStream.FlushFinalBlock();
var cipherBytes = memoryStream.ToArray();
memoryStream.Close();
cryptoStream.Close();
var cipherText = Convert.ToBase64String(cipherBytes, 0, cipherBytes.Length);
return cipherText;
}
public string Decrypt(string data, string key)
{
if (!string.IsNullOrEmpty(key))
{
CustomKey(key);
}
var encryptor = Aes.Create();
encryptor.Mode = CipherMode.CBC;
var aesKey = new byte[32];
Array.Copy(_key, 0, aesKey, 0, 32);
encryptor.Key = aesKey;
encryptor.IV = _iv;
var memoryStream = new MemoryStream();
var aesDecryptor = encryptor.CreateDecryptor();
var cryptoStream = new CryptoStream(memoryStream, aesDecryptor, CryptoStreamMode.Write);
var plainText = string.Empty;
try
{
var cipherBytes = Convert.FromBase64String(data);
cryptoStream.Write(cipherBytes, 0, cipherBytes.Length);
cryptoStream.FlushFinalBlock();
var plainBytes = memoryStream.ToArray();
plainText = Encoding.ASCII.GetString(plainBytes, 0, plainBytes.Length);
}
finally
{
memoryStream.Close();
cryptoStream.Close();
}
return plainText;
}
private void CustomKey(string key)
{
var blockSize = key.Length / _divisionKey;
var splitKey = key.CutString(blockSize).ToList();
var splitDefaultKey = _defaultKey.CutString(blockSize).ToList();
var newKey = string.Concat(splitDefaultKey.Intertwine(splitKey).ToList());
_key = SHA256.Create().ComputeHash(Encoding.ASCII.GetBytes(newKey));
}
}
}
JAVA test...
import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
public class SecurityAESEncryption {
private static final String _key = "sjkdhfjksdhf3444KDFK4nFLFGKdsnjcnj2cmkeKDIK484dmd999sksksksUUddUZ83k030394m49jdjPuWzRk8Zq2PfnpR3YrYWSq2AaUT6meeC3tr36nTVkuudKWbDyPjhUwbwXBzkUhSPKPpSRheR49em4qJWa6YHSCjKX3K93FEMnqXhYauXwjJwbHXfPWTSdxy6ebCBPyAfqk7Uz5nrRddVjZrxWNCMZYG3PbcvPWA34ekdkd454ldnvJKl";
private static final char[] initCharArray = new char[] {0x26, 0xdc, 0xff, 0x00, 0xad, 0xed, 0x7a, 0xee, 0xc5, 0xfe, 0x07, 0xaf, 0x4d, 0x08, 0x22, 0x3c};
private static final byte[] initVector = SecurityAESEncryption.charToByteArray(initCharArray);
//private static final String initArray = "26dcff00aded7aeec5fe07af4d08223c";
//private static final byte[] ivValue = SecurityAESEncryption.hexStringToByteArray(initArray);
//private static final byte[] key = DigestUtils.sha256(_key.getBytes(StandardCharsets.US_ASCII)).;
private static final byte[] key = SecurityAESEncryption.computeHash(_key);
public static String encrypt(String value) {
try {
System.out.println(key.length);
System.out.println(Base64.decodeBase64(key).length);
byte[] aesKey = new byte[32];
System.arraycopy(key, 0, aesKey, 0, 32);
SecretKeySpec skeySpec = new SecretKeySpec(aesKey, "AES");
IvParameterSpec iv = new IvParameterSpec(initVector);
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
cipher.init(Cipher.ENCRYPT_MODE, skeySpec, iv);
byte[] encrypted = cipher.doFinal(value.getBytes());
return Base64.encodeBase64String(encrypted);
} catch (Exception ex) {
ex.printStackTrace();
}
return null;
}
public static String decrypt(String encrypted) {
try {
byte[] encryptedBytes = Base64.decodeBase64(encrypted);
System.out.println(key.length);
System.out.println(Base64.decodeBase64(key).length);
byte[] aesKey = new byte[32];
System.arraycopy(key, 0, aesKey, 0, 32);
IvParameterSpec iv = new IvParameterSpec(initVector);
SecretKeySpec skeySpec = new SecretKeySpec(aesKey, "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
cipher.init(Cipher.DECRYPT_MODE, skeySpec, iv);
//byte[] original = cipher.doFinal(Base64.decodeBase64(encrypted));
byte[] original = cipher.doFinal(encryptedBytes);
return new String(original,StandardCharsets.US_ASCII);
} catch (Exception ex) {
ex.printStackTrace();
}
return null;
}
public static byte[] charToByteArray(char[] x)
{
final byte[] res = new byte[x.length];
for (int i = 0; i < x.length; i++)
{
res[i] = (byte) x[i];
}
return res;
}
public static byte[] computeHash(String input) {
try {
// Static getInstance method is called with hashing SHA
MessageDigest md = MessageDigest.getInstance("SHA-256");
return md.digest(input.getBytes(StandardCharsets.US_ASCII));
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
}
return null;
}
public static byte[] hexStringToByteArray(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;
}
public static void main(String[] args) {
String originalString = "123456!##";
System.out.println("Original String to encrypt - " + originalString);
String encryptedString = encrypt(originalString);
System.out.println("Encrypted String - " + encryptedString);
String decryptedString = decrypt("Ci10C7ZjUPoEnitdh7QkEw==");
System.out.println("After decryption - " + decryptedString);
}

Your edited Java prog now successfully encrypts the string "123456!##" to this (Base64 encoded) string "LnZV0Vph+eUeJLT2Gst0kw==" using a String as input to a SHA-256 digest, so the real key used for en-/decryption is
(hex) "07c3491eaa6a6289ca91b7b0f290d60688538860b44753f1cf9617977985d2db".
Using this encoded string as input for your decrypt method returns the original string but when using the encoded/encrypted
string "Ci10C7ZjUPoEnitdh7QkEw==" I'm running into this exception:
javax.crypto.BadPaddingException: Given final block not properly padded.
Such issues can arise if a bad key is used during decryption.
Imho this indicates that the key your're using on Java-side is not the same as on C#-side (we don't see the real input
to Encrypt and I don't know what "CustomKey" is doing :-).
Could you please print out
the aeskey and -iv from your C#-Encrypt method directly after you setup them in encryptor-inits and share them here,
that might be usefull for us to help.
public string Encrypt(string data, string key)
...
// Set key and IV
var aesKey = new byte[32];
Array.Copy(_key, 0, aesKey, 0, 32);
encryptor.Key = aesKey;
encryptor.IV = _iv;
==> print aesKey & _iv
...

NodeJs Decrypt AES256 Encryption From JAVA

I'm doing an integration with another system and the data given is encrypted in AES-256-CBC(Java) and need to decrypt it in NodeJs in order to proceed.
I have tried many ways from internet and stuck in error. Below is the sample code of Java(decryption) which is working and NodeJs(my code of decryption)
private static final int ITERATION_COUNT = 65536;
private static final int KEY_LENGTH = 256;
private static final byte[] DEFAULT_IV = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
public static byte[] decryptToBytes(String src, String secret, String salt, byte[] iv) {
try{
IvParameterSpec ivspec = new IvParameterSpec(iv);
SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA256");
KeySpec spec = new PBEKeySpec(secret.toCharArray(), salt.getBytes(), ITERATION_COUNT, KEY_LENGTH);
SecretKey tmp = factory.generateSecret(spec);
SecretKeySpec secretKey = new SecretKeySpec(tmp.getEncoded(), "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
cipher.init(Cipher.DECRYPT_MODE, secretKey, ivspec);
return cipher.doFinal(Base64.getDecoder().decode(src));
}catch (Exception ex) {
ex.printStackTrace();
}
return null;
}
public static String decrypt(String src, String secret, String salt, byte[] iv) {
try{
return new String(decryptToBytes(src, secret, salt, iv));
}catch (Exception ex) {
return null;
}
}
public static void main(String[] args) {
String secret = "abcd123456";
String salt = "123abc";
String plainText ="This is AES256 encryption test";
String cipherText = "gbYgtu5EWxOYRSUmMsEtdn8oQLxBjejfwUBSRhhls08=";
byte[] IV = new byte[16];
String originalText = decrypt(cipherText,secret, salt, IV);
}
import crypto from "crypto";
public aesCdcDecrypt(input: string) {
let iterationCount = 65536;
let keyLength = 256;
let iv = new Buffer(16);
let keyHex = "abcd123456";
let salt = "123abc";
let decryptText: string;
try {
crypto.pbkdf2(new Buffer(keyHex), new Buffer(salt), iterationCount, keyLength, "sha256", function (err, key) {
let secretKey = key.toString("hex");
let decipher = crypto.createDecipheriv("aes-256-cbc", secretKey, iv);
decryptText = decipher.update(input, "binary", "utf8");
decryptText += decipher.final("utf8");
console.log('Result: ' + decryptText);
});
} catch (e) {
console.log(e);
}
return decryptText;
}
Result getting this error -->
Error: Invalid key length
at new Decipheriv (crypto.js:267:16)
at Object.createDecipheriv (crypto.js:627:10)

There are a few minor issues in your TS code:
key length is in bytes, not bits
new Buffer() does not decode base64 by default
Here's a working version (JS):
const crypto = require('crypto')
function aesCdcDecrypt(ciphertext) {
let iterationCount = 65536;
let keyLength = 32;
let iv = Buffer.alloc(16);
let keyHex = "abcd123456";
let salt = "123abc";
let key = crypto.pbkdf2Sync(keyHex, Buffer.from(salt), iterationCount, keyLength, "sha256");
var cipher = crypto.createDecipheriv("aes-256-cbc", key, iv);
cipher.setAutoPadding(true);
let ciph = cipher.update(Buffer.from(ciphertext, "base64"));
let ciphf = cipher.final();
return Buffer.concat([ciph, ciphf]).toString();
}
console.log(aesCdcDecrypt("gbYgtu5EWxOYRSUmMsEtdn8oQLxBjejfwUBSRhhls08="));
Prints:
This is AES256 encryption test

Encryption using AES-128 in Android and IPhone (Different result)

I am trying to encrypt some text using the AES algorithm on both the Android and IPhone platforms. My problem is, even using the same encryption/decryption algorithm (AES-128) and same fixed variables (key, IV, mode), I get different result on both platforms. I am including code samples from both platforms, that I am using to test the encryption/decryption. I would appreciate some help in determining what I am doing wrong.
Key: “123456789abcdefg”
IV: “1111111111111111”
Plain Text: “HelloThere”
Mode: “AES/CBC/NoPadding”
Android Code:
public class Crypto {
private final static String HEX = "0123456789ABCDEF";
public static String encrypt(String seed, String cleartext)
throws Exception {
byte[] rawKey = getRawKey(seed.getBytes());
byte[] result = encrypt(rawKey, cleartext.getBytes());
return toHex(result);
}
public static String decrypt(String seed, String encrypted)
throws Exception {
byte[] rawKey = getRawKey(seed.getBytes());
byte[] enc = toByte(encrypted);
byte[] result = decrypt(rawKey, enc);
return new String(result);
}
private static byte[] getRawKey(byte[] seed) throws Exception {
KeyGenerator kgen = KeyGenerator.getInstance("CBC");
SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");
sr.setSeed(seed);
kgen.init(128, sr); // 192 and 256 bits may not be available
SecretKey skey = kgen.generateKey();
byte[] raw = skey.getEncoded();
return raw;
}
private static byte[] encrypt(byte[] raw, byte[] clear) throws Exception {
SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
byte[] encrypted = cipher.doFinal(clear);
return encrypted;
}
private static byte[] decrypt(byte[] raw, byte[] encrypted)
throws Exception {
SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.DECRYPT_MODE, skeySpec);
byte[] decrypted = cipher.doFinal(encrypted);
return decrypted;
}
public static String toHex(String txt) {
return toHex(txt.getBytes());
}
public static String fromHex(String hex) {
return new String(toByte(hex));
}
public static byte[] toByte(String hexString) {
int len = hexString.length() / 2;
byte[] result = new byte[len];
for (int i = 0; i < len; i++)
result[i] = Integer.valueOf(hexString.substring(2 * i, 2 * i + 2),
16).byteValue();
return result;
}
public static String toHex(byte[] buf) {
if (buf == null)
return "";
StringBuffer result = new StringBuffer(2 * buf.length);
for (int i = 0; i < buf.length; i++) {
appendHex(result, buf[i]);
}
return result.toString();
}
private static void appendHex(StringBuffer sb, byte b) {
sb.append(HEX.charAt((b >> 4) & 0x0f)).append(HEX.charAt(b & 0x0f));
}
}
IPhone (Objective-C) Code:
- (NSData *) transform:(CCOperation) encryptOrDecrypt data:(NSData *) inputData {
NSData* secretKey = [Cipher md5:cipherKey];
CCCryptorRef cryptor = NULL;
CCCryptorStatus status = kCCSuccess;
uint8_t iv[kCCBlockSizeAES128];
memset((void *) iv, 0x0, (size_t) sizeof(iv));
status = CCCryptorCreate(encryptOrDecrypt, kCCAlgorithmAES128, kCCOptionPKCS7Padding,
[secretKey bytes], kCCKeySizeAES128, iv, &cryptor);
if (status != kCCSuccess) {
return nil;
}
size_t bufsize = CCCryptorGetOutputLength(cryptor, (size_t)[inputData length], true);
void * buf = malloc(bufsize * sizeof(uint8_t));
memset(buf, 0x0, bufsize);
size_t bufused = 0;
size_t bytesTotal = 0;
status = CCCryptorUpdate(cryptor, [inputData bytes], (size_t)[inputData length],
buf, bufsize, &bufused);
if (status != kCCSuccess) {
free(buf);
CCCryptorRelease(cryptor);
return nil;
}
bytesTotal += bufused;
status = CCCryptorFinal(cryptor, buf + bufused, bufsize - bufused, &bufused);
if (status != kCCSuccess) {
free(buf);
CCCryptorRelease(cryptor);
return nil;
}
bytesTotal += bufused;
CCCryptorRelease(cryptor);
return [NSData dataWithBytesNoCopy:buf length:bytesTotal];
}
+ (NSData *) md5:(NSString *) stringToHash {
const char *src = [stringToHash UTF8String];
unsigned char result[CC_MD5_DIGEST_LENGTH];
CC_MD5(src, strlen(src), result);
return [NSData dataWithBytes:result length:CC_MD5_DIGEST_LENGTH];
}
Some of my references :
http://code.google.com/p/aes-encryption-samples/wiki/HowToEncryptWithJava
http://automagical.rationalmind.net/2009/02/12/aes-interoperability-between-net-and-iphone/
AES interoperability between .Net and iPhone?

For iPhone I used AESCrypt-ObjC, and for Android use this code:
public class AESCrypt {
private final Cipher cipher;
private final SecretKeySpec key;
private AlgorithmParameterSpec spec;
public AESCrypt(String password) throws Exception
{
// hash password with SHA-256 and crop the output to 128-bit for key
MessageDigest digest = MessageDigest.getInstance("SHA-256");
digest.update(password.getBytes("UTF-8"));
byte[] keyBytes = new byte[32];
System.arraycopy(digest.digest(), 0, keyBytes, 0, keyBytes.length);
cipher = Cipher.getInstance("AES/CBC/PKCS7Padding");
key = new SecretKeySpec(keyBytes, "AES");
spec = getIV();
}
public AlgorithmParameterSpec getIV()
{
byte[] iv = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, };
IvParameterSpec ivParameterSpec;
ivParameterSpec = new IvParameterSpec(iv);
return ivParameterSpec;
}
public String encrypt(String plainText) throws Exception
{
cipher.init(Cipher.ENCRYPT_MODE, key, spec);
byte[] encrypted = cipher.doFinal(plainText.getBytes("UTF-8"));
String encryptedText = new String(Base64.encode(encrypted, Base64.DEFAULT), "UTF-8");
return encryptedText;
}
public String decrypt(String cryptedText) throws Exception
{
cipher.init(Cipher.DECRYPT_MODE, key, spec);
byte[] bytes = Base64.decode(cryptedText, Base64.DEFAULT);
byte[] decrypted = cipher.doFinal(bytes);
String decryptedText = new String(decrypted, "UTF-8");
return decryptedText;
}
}

It makes me no wonder that you get different results.
Your problem is that you use misuse a SHA1PRNG for key derivation. AFAIK there is no common standard how a SHA1PRNG work internally. AFAIR even the J2SE and Bouncycaste implementation output different results using the same seed.
Hence your implementation of your getRawKey(byte[] seed) will generate you a random key. If you use the key for encryption you are getting an result that depends on that key. As the key is random you will not get the same key on iOS and therefore you are getting a different result.
If you want a key derivation function use a function like PBKDF2 with is nearly fully standardized regarding the key derivation.

On Android, you are using getBytes(). This is an error as it means you are using the default charset rather than a known charset. Use getBytes("UTF-8") instead so you know exactly what bytes you are going to get.
I don't know the equivalent for Objective-C, but don't rely on the default. Explicitly specify UTF-8 when converting strings to bytes. That way you will get the same bytes on both sides.
I also note that you are using MD5 in the Objective-C code but not in the Android code. Is this deliberate?

See my answer for password-based AES encryption, since, you are effectively using your "seed" as a password. (Just change the key length of 256 to 128, if that's what you want.)
Trying to generate the same key by seeding a DRBG with the same value is not reliable.
Next, you are not using CBC or the IV in your Android encryption. My example shows how to do that properly too. By the way, you need to generate a new IV for every message you encrypt, as my example shows, and send it along with the cipher text. Otherwise, there's no point in using CBC.

Note: For android in java
I have written this manager file and its functions are working perfectly fine for me. This is for AES 128 and without any salt.
public class CryptoManager {
private static CryptoManager shared;
private String privateKey = "your_private_key_here";
private String ivString = "your_iv_here";
private CryptoManager(){
}
public static CryptoManager getShared() {
if (shared != null ){
return shared;
}else{
shared = new CryptoManager();
return shared;
}
}
public String encrypt(String value) {
try {
IvParameterSpec iv = new IvParameterSpec(ivString.getBytes("UTF-8"));
SecretKeySpec skeySpec = new SecretKeySpec(privateKey.getBytes("UTF-8"), "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
cipher.init(Cipher.ENCRYPT_MODE, skeySpec, iv);
byte[] encrypted = cipher.doFinal(value.getBytes());
return android.util.Base64.encodeToString(encrypted, android.util.Base64.DEFAULT);
} catch (Exception ex) {
ex.printStackTrace();
}
return null;
}
public String decrypt(String encrypted) {
try {
IvParameterSpec iv = new IvParameterSpec(ivString.getBytes("UTF-8"));
SecretKeySpec skeySpec = new SecretKeySpec(privateKey.getBytes("UTF-8"), "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
cipher.init(Cipher.DECRYPT_MODE, skeySpec, iv);
byte[] original = new byte[0];
original = cipher.doFinal(android.util.Base64.decode(encrypted, android.util.Base64.DEFAULT));
return new String(original);
} catch (Exception ex) {
ex.printStackTrace();
}
return null;
}
}
You need to call the functions like this.
String dataToEncrypt = "I need to encrypt myself";
String encryptedData = CryptoManager.getShared().encrypt(data);
And you will get your encrypted string with the following line
String decryptedString = CryptoManager.getShared().decrypt(encryptedData);

If you want an example of compatible code for Android and iPhone, look at the RNCryptor library for iOS and the JNCryptor library for Java/Android.
Both projects are open source and share a common data format. In these libraries, AES 256-bit is used, however it would be trivial to adapt the code if necessary to support 128-bit AES.
As per the accepted answer, both libraries use PBKDF2.

Unable to decrypt the encrypted sms (encrypted in 2.2 os )in Android...(trying to decrypt in 2.3 os)

I am able to encrypt an SMS and send it from one simulator (Android 2.2) to another.
On the receiving end I am able to do the decryption successfully. But the problem is if do the encryption in one OS version (i.e Android 2.2) and trying to decrypt in another OS version ( Android 2.3 ) i am getting 'Bad padding exception'. I checked that i used the same key on both ends.
The code is shown below
public class ED {
private String Key;
public ED() {
Key = "abc12"; // Assigning default key.
}
public ED(String key) {
// TODO Auto-generated constructor stub
Key = key;
}
public String encrypt(String toEncrypt) throws Exception {
byte[] rawKey = getRawKey(Key.getBytes("UTF-8"));
byte[] result = encrypt(rawKey, toEncrypt.getBytes("UTF-8"));
return toHex(result);
}
public byte[] encrypt(byte[] key, byte[] toEncodeString) throws Exception {
SecretKeySpec sKeySpec = new SecretKeySpec(key, "AES");
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.ENCRYPT_MODE, sKeySpec);
byte[] encrypted = cipher.doFinal(toEncodeString);
return encrypted;
}
private byte[] getRawKey(byte[] key) throws Exception {
KeyGenerator kGen = KeyGenerator.getInstance("AES");
SecureRandom sr = SecureRandom.getInstance("SHA1PRNG");
sr.setSeed(key);
kGen.init(128, sr);
SecretKey sKey = kGen.generateKey();
byte[] raw = sKey.getEncoded();
return raw;
}
/************************************* Decription *********************************************/
public String decrypt(String encryptedString) throws Exception {
byte[] rawKey = getRawKey(Key.getBytes("UTF-8"));
System.out.println("Decrypted Key in bytes : "+rawKey);
System.out.println("Key in decryption :"+rawKey);
SecretKeySpec sKeySpec = new SecretKeySpec(rawKey, "AES");
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.DECRYPT_MODE, sKeySpec);
byte[] decrypted = cipher.doFinal(toByte(encryptedString));
System.out.println("Decrypted mess in bytes---------->" +decrypted);
return new String(decrypted);
}
public String toHex(byte[] buf) {
if (buf == null)
return "";
StringBuffer result = new StringBuffer(2*buf.length);
for (int i = 0; i < buf.length; i++) {
appendHex(result, buf[i]);
}
return result.toString();
}
private final String HEX = "0123456789ABCDEF";
private void appendHex(StringBuffer sb, byte b) {
sb.append(HEX.charAt((b>>4)&0x0f)).append(HEX.charAt(b&0x0f));
}
public byte[] toByte(String hexString) {
int len = hexString.length()/2;
byte[] result = new byte[len];
for (int i = 0; i < len; i++)
result[i] = Integer.valueOf(hexString.substring(2*i, 2*i+2), 16).byteValue();
return result;
}
}
And I am using sendTextMessage() function to send an sms. I read that encryption/decryption doesn't depend on OS but in this case that is not true. Am I missing any important things while configuring the Cipher (in AES) ? Please let me know.

It's setSeed(). It does not do what you think it does: it just adds the entropy of the given seed to the underlying algorithm. You'll probably find out that it returns somehthing different on both platforms. SHA1PRNG is a pseudo random function, but if it is already seeded, it's likely to return different results.

If the problem is in the key length, you could derivate a key from your password, instead of using it directly. You could use a Hash (like SHA-1, MD5, etc) and crop it to the correct size (128, 192 or 256 bits), or use PBEKeySpec instead of SecretKeySpec.
That to remove problems with the key length. If the padding problems were in the plaintext, I suggest you to use CipherInputStream and CipherOutputStream, which are more programmer-friendly to use than Cipher.doFinal.

Don't rely on KeyGenerator to generate the same key just because you seeded the RNG the same way. If you are pre-sharing a key, share the key, not the seed.
You should also specify the encryption transform completely: "AES/ECB/PKCS5Padding"
Finally, ECB mode is not secure for general use.
See another answer of mine for an example to perform encryption correctly with the JCE.

The problem is with SecureRandom generation. It is giving different results on different platforms. It's because of a bug fix on line 320 (in Gingerbread source) of SHA1PRNG_SecureRandomImpl.java in the engineNextBytes() method where
bits = seedLength << 3 + 64;
was changed to
bits = (seedLength << 3) + 64;
Use SecretKeyFactory() to generate a Secure key instead of secure random.
public class Crypto {
Cipher ecipher;
Cipher dcipher;
byte[] salt = { 1, 2, 4, 5, 7, 8, 3, 6 };
int iterationCount = 1979;
Crypto(String passPhase) {
try {
// Create the key
KeySpec keySpec = new PBEKeySpec(passPhase.toCharArray(), salt, iterationCount);
SecretKey key = SecretKeyFactory.getInstance("PBEWITHSHA256AND128BITAES-CBC-BC").generateSecret(keySpec);
ecipher = Cipher.getInstance(key.getAlgorithm());
dcipher = Cipher.getInstance(key.getAlgorithm());
AlgorithmParameterSpec paramSpec = new PBEParameterSpec(salt, iterationCount);
ecipher.init(Cipher.ENCRYPT_MODE, key, paramSpec);
dcipher.init(Cipher.DECRYPT_MODE, key, paramSpec);
} catch (Exception e) {
// TODO: handle exception
//Toast.makeText(this, "I cought ", Toast.LENGTH_LONG).show();
}
}
public String encrypt(String str) {
String rVal;
try {
byte[] utf8 = str.getBytes("UTF8");
byte[] enc = ecipher.doFinal(utf8);
rVal = toHex(enc);
} catch (Exception e) {
// TODO: handle exception
rVal = "Exception Caught "+e.getMessage();
}
return rVal;
}
public String decrypt(String str) {
String rVal;
try {
byte[] dec = toByte(str);
byte[] utf8 = dcipher.doFinal(dec);
rVal = new String(utf8, "UTF8");
} catch(Exception e) {
rVal = "Error in decrypting :"+e.getMessage();
}
return rVal;
}
private static byte[] toByte(String hexString ) {
int len = hexString.length()/2;
byte[] result = new byte[len];
for ( int i=0; i<len; i++ ) {
result[i] = Integer.valueOf(hexString.substring(2*i, 2*i+2), 16 ).byteValue();
}
return result;
}
private static String toHex(byte[] buf) {
if (buf == null)
return "";
StringBuffer result = new StringBuffer( 2*buf.length);
for ( int i=0; i<buf.length; i++) {
appendHex(result, buf[i]);
}
return result.toString();
}
private final static String HEX = "0123456789ABCDEF";
private static void appendHex(StringBuffer sb, byte b) {
sb.append(HEX.charAt((b >> 4) & 0x0f)).append(HEX.charAt(b & 0x0f));
}
}