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Reverse-engineering Java AES-based encryption

I'm trying to reverse-engineer this Java code in C#, but I keep getting wrong result:
public static String GetEncodedToken(String tokenBase64) {
String str2 = "";
try {
byte[] ivBytes = Base64Coder.decode("OSMqNE11fGUoLDg5Mmk1WQ==");
byte[] keyBytes = Base64Coder.decode("Nm4wMy5nOiM3JSpWfnwzOXFpNzRcfjB5MVNEKl8mWkw=");
byte[] tokenBytes = Base64Coder.decode(tokenBase64);
byte[] tokenEncBytes = Encrypt(ivBytes, keyBytes, tokenBytes);
str2 = URLEncoder.encode(Base64Coder.encode(tokenEncBytes), "UTF-8");
} catch (Exception e) {
}
return str2;
}
private static byte[] Encrypt(byte[] ivBytes, byte[] keyBytes, byte[] tokenBytes) throws UnsupportedEncodingException, NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, InvalidAlgorithmParameterException, IllegalStateException, IllegalBlockSizeException, BadPaddingException {
AlgorithmParameterSpec ivParameterSpec = new IvParameterSpec(ivBytes);
Key secretKeySpec = new SecretKeySpec(keyBytes, "AES");
Cipher instance = Cipher.getInstance("AES/CBC/PKCS5Padding");
instance.init(1, secretKeySpec, ivParameterSpec); // 1 = CipherMode.CBC in C#???
return instance.doFinal(tokenBytes);
}
In my understanding the code above in C# translates to the following snippet:
public static string GetEncodedToken(string tokenBase64)
{
var ivBytes = Convert.FromBase64String("OSMqNE11fGUoLDg5Mmk1WQ==");
var keyBytes = Convert.FromBase64String("Nm4wMy5nOiM3JSpWfnwzOXFpNzRcfjB5MVNEKl8mWkw=");
var tokenBytes = Convert.FromBase64String(tokenBase64);
var tokenEncBytes = Crypt.Encrypt(tokenBytes, keyBytes, ivBytes);
var tokenEnc = HttpUtility.UrlEncode(Convert.ToBase64String(tokenEncBytes));
return tokenEnc;
}
private static byte[] Encrypt(byte[] tokenBytes, byte[] keyBytes, byte[] ivBytes)
{
using (var rijndaelManaged = new RijndaelManaged
{
Mode = CipherMode.CBC,
Padding = PaddingMode.PKCS7,
KeySize = 128,
BlockSize = 128,
Key = keyBytes,
IV = ivBytes
})
{
return rijndaelManaged.CreateEncryptor()
.TransformFinalBlock(tokenBytes, 0, tokenBytes.Length);
}
}
However the API I'm trying to log in via C# client tells me the token is wrong :(

javax.crypto.BadPaddingException: error:1e06b065:Cipher functions:EVP_DecryptFinal_ex:BAD_DECRYPT exception

I have this code :
public static void EncryptFile_Aes(string inputFile, string outputFile, byte[] key)
{
using (Aes aesAlg = Aes.Create())
{
aesAlg.Key = key;
aesAlg.Mode = CipherMode.CBC;
var encryptor = aesAlg.CreateEncryptor(aesAlg.Key, aesAlg.IV);
using (FileStream outputStream = new FileStream(outputFile, FileMode.Create))
{
using (var cryptoStream = new CryptoStream(outputStream, encryptor, CryptoStreamMode.Write))
{
FileStream inputStream = new FileStream(inputFile, FileMode.Open);
int data;
while ((data = inputStream.ReadByte()) != -1)
{
cryptoStream.WriteByte((byte)data);
}
}
}
}
with secret key "MySecret". I need to decrypt this code into java or android. But I got this exception,
javax.crypto.BadPaddingException: error:1e06b065:Cipher functions:EVP_DecryptFinal_ex:BAD_DECRYPT
code in java,
private byte[] getRawKey(byte[] seed) throws Exception {
KeyGenerator kgen = KeyGenerator.getInstance("AES");
SecureRandom sr = SecureRandom.getInstance("SHA1PRNG","Crypto");
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 byte[] decrypt(byte[] raw, byte[] encrypted) throws Exception {
SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
// Cipher cipher = Cipher.getInstance("AES");
IvParameterSpec ivSpec = new IvParameterSpec(raw);
Cipher cipher = Cipher.getInstance("CBC");
cipher.init(Cipher.DECRYPT_MODE, skeySpec,ivSpec);
byte[] decrypted = cipher.doFinal(encrypted);
return decrypted;
}
Please help me to vanish that exception.

How to print an AES-encrypted string so it is reusable in another application? [duplicate]

I have a hardcoded key with which I want to encrypt a string before storing it in SharedPreferences. This is the code I have so far:
public class TokenEncryptor {
private final static String TOKEN_KEY = "91a29fa7w46d8x41";
public static String encrypt(String plain) {
try {
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
AlgorithmParameterSpec ivSpec = new IvParameterSpec(new byte[16]);
SecretKeySpec newKey = new SecretKeySpec(TOKEN_KEY.getBytes(), "AES");
cipher.init(Cipher.ENCRYPT_MODE, newKey, ivSpec);
return new String(cipher.doFinal(plain.getBytes()));
} catch (Exception e) {
Ln.e(e);
return null;
}
}
public static String decrypt(String encoded) {
try {
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
AlgorithmParameterSpec ivSpec = new IvParameterSpec(new byte[16]);
SecretKeySpec newKey = new SecretKeySpec(TOKEN_KEY.getBytes(), "AES");
cipher.init(Cipher.DECRYPT_MODE, newKey, ivSpec);
return new String(cipher.doFinal(encoded.getBytes()));
} catch (Exception e) {
Ln.e(e);
return null;
}
}
}
It seems to be catching an exception at the end of decrypt method:
javax.crypto.IllegalBlockSizeException: error:0606506D:digital envelope routines:EVP_DecryptFinal_ex:wrong final block length
Can someone point me in the right direction? I have a feeling I'm doing something wrong instantiating IvParameterSpec.

When you encrypt a string with AES, you get an array of bytes back. Trying to convert those bytes directly to a string (new String(cipher.doFinal(plaintextBytes))) will cause all sorts of problems. If you require the output from your encryption method to be a string, then use Base64 rather than attempting a direct conversion. In your decryption method, convert the Base64 string back into a byte array before decrypting the byte array.
Also, do not use getBytes() since the output depends on the system defaults. Use getBytes("utf-8") or whatever. That eliminates ambiguity.

Just in case anyone is interested (or feels too lazy to do their research), here is the the result code for AES-256 encryption and decryption that I put together, with help from the accepted answer and comments:
public class TokenEncryptor {
private final static String TOKEN_KEY = "fqJfdzGDvfwbedsKSUGty3VZ9taXxMVw";
public static String encrypt(String plain) {
try {
byte[] iv = new byte[16];
new SecureRandom().nextBytes(iv);
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
cipher.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(TOKEN_KEY.getBytes("utf-8"), "AES"), new IvParameterSpec(iv));
byte[] cipherText = cipher.doFinal(plain.getBytes("utf-8"));
byte[] ivAndCipherText = getCombinedArray(iv, cipherText);
return Base64.encodeToString(ivAndCipherText, Base64.NO_WRAP);
} catch (Exception e) {
Ln.e(e);
return null;
}
}
public static String decrypt(String encoded) {
try {
byte[] ivAndCipherText = Base64.decode(encoded, Base64.NO_WRAP);
byte[] iv = Arrays.copyOfRange(ivAndCipherText, 0, 16);
byte[] cipherText = Arrays.copyOfRange(ivAndCipherText, 16, ivAndCipherText.length);
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(TOKEN_KEY.getBytes("utf-8"), "AES"), new IvParameterSpec(iv));
return new String(cipher.doFinal(cipherText), "utf-8");
} catch (Exception e) {
Ln.e(e);
return null;
}
}
private static byte[] getCombinedArray(byte[] one, byte[] two) {
byte[] combined = new byte[one.length + two.length];
for (int i = 0; i < combined.length; ++i) {
combined[i] = i < one.length ? one[i] : two[i - one.length];
}
return combined;
}
}

It's an extension of Artjom B answer and working for me.
public String encryptMsg(String message, SecretKey secret)
throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, InvalidParameterSpecException, IllegalBlockSizeException, BadPaddingException, UnsupportedEncodingException {
Cipher cipher = null;
cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
cipher.init(Cipher.ENCRYPT_MODE, secret);
byte[] cipherText = cipher.doFinal(message.getBytes("UTF-8"));
return Base64.encodeToString(cipherText, Base64.NO_WRAP);
}
public String decryptMsg(String cipherText, SecretKey secret)
throws NoSuchPaddingException, NoSuchAlgorithmException, InvalidParameterSpecException, InvalidAlgorithmParameterException, InvalidKeyException, BadPaddingException, IllegalBlockSizeException, UnsupportedEncodingException {
Cipher cipher = null;
cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
cipher.init(Cipher.DECRYPT_MODE, secret);
byte[] decode = Base64.decode(cipherText, Base64.NO_WRAP);
String decryptString = new String(cipher.doFinal(decode), "UTF-8");
return decryptString;
}

Kotlin version of #Oleksiy 's answer.
<script src="https://gist.github.com/kasim1011/a5a9644a60c33a4df3c29f4b34cf93a4.js"></script>
import android.util.Base64
import java.util.*
import javax.crypto.Cipher
import javax.crypto.spec.IvParameterSpec
import javax.crypto.spec.SecretKeySpec
private const val algorithm = "AES"
private const val tokenKey = "fqJfdzGDvfwbedsKSUGty3VZ9taXxMVw"
private const val padding = "AES/CBC/PKCS5Padding"
private const val ivSize = 16
fun String.encryptAES(): String {
val tokenBytes = tokenKey.toByteArray(Charsets.UTF_8)
val secretKey = SecretKeySpec(tokenBytes, algorithm)
val ivByteArray = ByteArray(ivSize)
val iv = IvParameterSpec(ivByteArray)
val cipher = Cipher.getInstance(padding)
cipher.init(Cipher.ENCRYPT_MODE, secretKey, iv)
val cipherText = cipher.doFinal(toByteArray(Charsets.UTF_8))
val ivAndCipherText = getCombinedArray(ivByteArray, cipherText)
return Base64.encodeToString(ivAndCipherText, Base64.NO_WRAP)
}
fun String.decryptAES(): String {
val tokenBytes = tokenKey.toByteArray(Charsets.UTF_8)
val secretKey = SecretKeySpec(tokenBytes, algorithm)
val ivAndCipherText = Base64.decode(this, Base64.NO_WRAP)
val cipherText = Arrays.copyOfRange(ivAndCipherText, ivSize, ivAndCipherText.size)
val ivByteArray = Arrays.copyOfRange(ivAndCipherText, 0, ivSize)
val iv = IvParameterSpec(ivByteArray)
val cipher = Cipher.getInstance(padding)
cipher.init(Cipher.DECRYPT_MODE, secretKey, iv)
return cipher.doFinal(cipherText).toString(Charsets.UTF_8)
}
private fun getCombinedArray(one: ByteArray, two: ByteArray): ByteArray {
val combined = ByteArray(one.size + two.size)
for (i in combined.indices) {
combined[i] = if (i < one.size) one[i] else two[i - one.size]
}
return combined
}

How can I fix the IllegalBlockSizeException? [duplicate]

I have a hardcoded key with which I want to encrypt a string before storing it in SharedPreferences. This is the code I have so far:
public class TokenEncryptor {
private final static String TOKEN_KEY = "91a29fa7w46d8x41";
public static String encrypt(String plain) {
try {
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
AlgorithmParameterSpec ivSpec = new IvParameterSpec(new byte[16]);
SecretKeySpec newKey = new SecretKeySpec(TOKEN_KEY.getBytes(), "AES");
cipher.init(Cipher.ENCRYPT_MODE, newKey, ivSpec);
return new String(cipher.doFinal(plain.getBytes()));
} catch (Exception e) {
Ln.e(e);
return null;
}
}
public static String decrypt(String encoded) {
try {
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
AlgorithmParameterSpec ivSpec = new IvParameterSpec(new byte[16]);
SecretKeySpec newKey = new SecretKeySpec(TOKEN_KEY.getBytes(), "AES");
cipher.init(Cipher.DECRYPT_MODE, newKey, ivSpec);
return new String(cipher.doFinal(encoded.getBytes()));
} catch (Exception e) {
Ln.e(e);
return null;
}
}
}
It seems to be catching an exception at the end of decrypt method:
javax.crypto.IllegalBlockSizeException: error:0606506D:digital envelope routines:EVP_DecryptFinal_ex:wrong final block length
Can someone point me in the right direction? I have a feeling I'm doing something wrong instantiating IvParameterSpec.

When you encrypt a string with AES, you get an array of bytes back. Trying to convert those bytes directly to a string (new String(cipher.doFinal(plaintextBytes))) will cause all sorts of problems. If you require the output from your encryption method to be a string, then use Base64 rather than attempting a direct conversion. In your decryption method, convert the Base64 string back into a byte array before decrypting the byte array.
Also, do not use getBytes() since the output depends on the system defaults. Use getBytes("utf-8") or whatever. That eliminates ambiguity.

Just in case anyone is interested (or feels too lazy to do their research), here is the the result code for AES-256 encryption and decryption that I put together, with help from the accepted answer and comments:
public class TokenEncryptor {
private final static String TOKEN_KEY = "fqJfdzGDvfwbedsKSUGty3VZ9taXxMVw";
public static String encrypt(String plain) {
try {
byte[] iv = new byte[16];
new SecureRandom().nextBytes(iv);
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
cipher.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(TOKEN_KEY.getBytes("utf-8"), "AES"), new IvParameterSpec(iv));
byte[] cipherText = cipher.doFinal(plain.getBytes("utf-8"));
byte[] ivAndCipherText = getCombinedArray(iv, cipherText);
return Base64.encodeToString(ivAndCipherText, Base64.NO_WRAP);
} catch (Exception e) {
Ln.e(e);
return null;
}
}
public static String decrypt(String encoded) {
try {
byte[] ivAndCipherText = Base64.decode(encoded, Base64.NO_WRAP);
byte[] iv = Arrays.copyOfRange(ivAndCipherText, 0, 16);
byte[] cipherText = Arrays.copyOfRange(ivAndCipherText, 16, ivAndCipherText.length);
Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(TOKEN_KEY.getBytes("utf-8"), "AES"), new IvParameterSpec(iv));
return new String(cipher.doFinal(cipherText), "utf-8");
} catch (Exception e) {
Ln.e(e);
return null;
}
}
private static byte[] getCombinedArray(byte[] one, byte[] two) {
byte[] combined = new byte[one.length + two.length];
for (int i = 0; i < combined.length; ++i) {
combined[i] = i < one.length ? one[i] : two[i - one.length];
}
return combined;
}
}

It's an extension of Artjom B answer and working for me.
public String encryptMsg(String message, SecretKey secret)
throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, InvalidParameterSpecException, IllegalBlockSizeException, BadPaddingException, UnsupportedEncodingException {
Cipher cipher = null;
cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
cipher.init(Cipher.ENCRYPT_MODE, secret);
byte[] cipherText = cipher.doFinal(message.getBytes("UTF-8"));
return Base64.encodeToString(cipherText, Base64.NO_WRAP);
}
public String decryptMsg(String cipherText, SecretKey secret)
throws NoSuchPaddingException, NoSuchAlgorithmException, InvalidParameterSpecException, InvalidAlgorithmParameterException, InvalidKeyException, BadPaddingException, IllegalBlockSizeException, UnsupportedEncodingException {
Cipher cipher = null;
cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
cipher.init(Cipher.DECRYPT_MODE, secret);
byte[] decode = Base64.decode(cipherText, Base64.NO_WRAP);
String decryptString = new String(cipher.doFinal(decode), "UTF-8");
return decryptString;
}

Kotlin version of #Oleksiy 's answer.
<script src="https://gist.github.com/kasim1011/a5a9644a60c33a4df3c29f4b34cf93a4.js"></script>
import android.util.Base64
import java.util.*
import javax.crypto.Cipher
import javax.crypto.spec.IvParameterSpec
import javax.crypto.spec.SecretKeySpec
private const val algorithm = "AES"
private const val tokenKey = "fqJfdzGDvfwbedsKSUGty3VZ9taXxMVw"
private const val padding = "AES/CBC/PKCS5Padding"
private const val ivSize = 16
fun String.encryptAES(): String {
val tokenBytes = tokenKey.toByteArray(Charsets.UTF_8)
val secretKey = SecretKeySpec(tokenBytes, algorithm)
val ivByteArray = ByteArray(ivSize)
val iv = IvParameterSpec(ivByteArray)
val cipher = Cipher.getInstance(padding)
cipher.init(Cipher.ENCRYPT_MODE, secretKey, iv)
val cipherText = cipher.doFinal(toByteArray(Charsets.UTF_8))
val ivAndCipherText = getCombinedArray(ivByteArray, cipherText)
return Base64.encodeToString(ivAndCipherText, Base64.NO_WRAP)
}
fun String.decryptAES(): String {
val tokenBytes = tokenKey.toByteArray(Charsets.UTF_8)
val secretKey = SecretKeySpec(tokenBytes, algorithm)
val ivAndCipherText = Base64.decode(this, Base64.NO_WRAP)
val cipherText = Arrays.copyOfRange(ivAndCipherText, ivSize, ivAndCipherText.size)
val ivByteArray = Arrays.copyOfRange(ivAndCipherText, 0, ivSize)
val iv = IvParameterSpec(ivByteArray)
val cipher = Cipher.getInstance(padding)
cipher.init(Cipher.DECRYPT_MODE, secretKey, iv)
return cipher.doFinal(cipherText).toString(Charsets.UTF_8)
}
private fun getCombinedArray(one: ByteArray, two: ByteArray): ByteArray {
val combined = ByteArray(one.size + two.size)
for (i in combined.indices) {
combined[i] = if (i < one.size) one[i] else two[i - one.size]
}
return combined
}

AES encryption j2me

I am trying to do AES encryption in j2me.I used almost same code for android and it's working fine there.Following is the block of code. I'm getting null as output
package cartoon;
import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
public class MCrypt {
private String iv = "0123456789abcdef";// iv
private IvParameterSpec ivspec;
private SecretKeySpec keyspec;
private Cipher cipher;
private String SecretKey = "fedcba9876543210";// secretKey
public MCrypt() {
ivspec = new IvParameterSpec(iv.getBytes(), 0, iv.getBytes().length);
keyspec = new SecretKeySpec(SecretKey.getBytes(), 0, iv.getBytes().length, "AES");
}
String Decrypt(String text) throws Exception {
cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
cipher.init(Cipher.DECRYPT_MODE, keyspec, ivspec);
byte[] results = null;
int results1 = cipher.doFinal(Base64.decode(text), 0, Base64.decode(text).length, results, 0);
System.out.println("String resultssssssssssssss " + results1);
return new String(results, "UTF-8");
}
String Encrypt(String text)
throws Exception {
cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
System.out.println("String input : " + text);
cipher.init(Cipher.ENCRYPT_MODE, keyspec, ivspec);
byte[] results = null;
int results1 = cipher.doFinal(text.getBytes(), 0, text.getBytes().length, results, 0);
return Base64.encode(results);
}
}
Printing result
MCrypt mcrypt = new MCrypt();
try {
encrypted = mcrypt.Encrypt("id=450");
decrypted = new String(mcrypt.Decrypt(encrypted));
System.out.println("Encrypted Text : " + encrypted);
System.out.println("Decrypted Text : " + decrypted);
} catch (Exception e) {
e.printStackTrace();
}
Where am I going wrong?

Try the following
You should initialize the byte array first appropriately
String Decrypt(String text) throws Exception {
cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
cipher.init(Cipher.DECRYPT_MODE, keyspec, ivspec);
// here
byte[] results = cipher.doFinal(Base64.decode(text));
int results1 = cipher.doFinal(Base64.decode(text), 0, Base64.decode(text).length, results, 0);
System.out.println("String resultssssssssssssss " + results1);
return new String(results, "UTF-8");
}
String Encrypt(String text)
throws Exception {
cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
System.out.println("String input : " + text);
cipher.init(Cipher.ENCRYPT_MODE, keyspec, ivspec);
// and here
byte[] results = cipher.doFinal(text.getBytes());
int results1 = cipher.doFinal(text.getBytes(), 0, text.getBytes().length, results, 0);
return Base64.encode(results);
}