Unable to replicate an encryption method from Java

Question

I have the following Java code

import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.KeyGenerator;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.SecretKeySpec;

import org.apache.commons.codec.binary.Base64;

public class AESEncryption 
{
    public static final String AES_TRANSFORMATION = "AES/ECB/PKCS5Padding";
    public static final String AES_ALGORITHM = "AES";
    public static final int ENC_BITS = 256;
    public static final String CHARACTER_ENCODING = "UTF-8";

    private static Cipher ENCRYPT_CIPHER;
    private static Cipher DECRYPT_CIPHER;
    private static KeyGenerator KEYGEN; 

    static
    {
        try
        {
            ENCRYPT_CIPHER = Cipher.getInstance(AES_TRANSFORMATION);
            DECRYPT_CIPHER = Cipher.getInstance(AES_TRANSFORMATION);
            KEYGEN = KeyGenerator.getInstance(AES_ALGORITHM);
            KEYGEN.init(ENC_BITS);
        }
        catch(NoSuchAlgorithmException | NoSuchPaddingException e) 
        {
            e.printStackTrace();
        }
    }

    /**
     * This method is used to encode bytes[] to base64 string.
     * 
     * @param bytes
     *            : Bytes to encode
     * @return : Encoded Base64 String
     */

    private static String encodeBase64String(byte[] bytes) 
    {
         return new String(java.util.Base64.getEncoder().encode(bytes));
    }

    /**
    * This method is used to decode the base64 encoded string to byte[]
    * 
    * @param stringData
    *            : String to decode
    * @return : decoded String
    * @throws UnsupportedEncodingException
    */

    private static byte[] decodeBase64StringTOByte(String stringData) throws Exception 
    {
        return java.util.Base64.getDecoder().decode(stringData.getBytes(CHARACTER_ENCODING));
    }

    /**
    * This method is used to encrypt the string which is passed to it as byte[] and return base64 encoded
    * encrypted String
    * @param plainText
    *            : byte[]
    * @param secret
    *            : Key using for encrypt
    * @return : base64 encoded of encrypted string.
    * 
    */

    private static String encryptEK(byte[] plainText, byte[] secret)
    {
        try
        {
            SecretKeySpec sk = new SecretKeySpec(secret, AES_ALGORITHM);
            ENCRYPT_CIPHER.init(Cipher.ENCRYPT_MODE, sk);
            return Base64.encodeBase64String(ENCRYPT_CIPHER.doFinal(plainText));    
        }
        catch(Exception e)
        {
            e.printStackTrace();
            return "";
        }
    }

    /**
    * This method is used to decrypt base64 encoded string using an AES 256 bit key.
    * 
    * @param plainText
    *            : plain text to decrypt
    * @param secret
    *            : key to decrypt
    * @return : Decrypted String
    * @throws IOException
    * @throws InvalidKeyException
    * @throws BadPaddingException
    * @throws IllegalBlockSizeException
    */
    public static byte[] decrypt(String plainText, byte[] secret)
                throws InvalidKeyException, IOException, IllegalBlockSizeException,
                BadPaddingException,Exception 
    {
        SecretKeySpec sk = new SecretKeySpec(secret, AES_ALGORITHM);
        DECRYPT_CIPHER.init(Cipher.DECRYPT_MODE, sk);       
        return DECRYPT_CIPHER.doFinal(Base64.decodeBase64(plainText));
    }

    public static void main(String args[])throws Exception
    {
        String encKey = ""; 

        //client asp_secret
        String asp_secret="";   


        byte[] enc_key = decrypt(encKey, asp_secret.getBytes());

        String enc_asp_secret=encryptEK(asp_secret.getBytes(), decodeBase64StringTOByte(encodeBase64String(enc_key)));

        System.out.println("asp secret encrypted:");
        System.out.println(enc_asp_secret);     
    }
}

I happened to see a very similar post in StackOverflow with no answers

Cannot replicate an AES 256 encryption code from Java to PHP [duplicate]

which is marked duplicate to another question which is different.

I have tried a couple of PHP codes but it didn't work out.

I will add up bounty for this as im trying this for ages.

Disclaimer : Used the same code snippet from the above question as this one is more clear.

Adding the PHP code I tried

class AtomAES {

public function encrypt($data = '', $key = NULL, $salt = "") {
    if($key != NULL && $data != "" && $salt != ""){

        $method = "AES-256-CBC";

        //Converting Array to bytes
        $iv = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15];
        $chars = array_map("chr", $iv);
        $IVbytes = join($chars);


        $salt1 = mb_convert_encoding($salt, "UTF-8"); //Encoding to UTF-8
        $key1 = mb_convert_encoding($key, "UTF-8"); //Encoding to UTF-8

        //SecretKeyFactory Instance of PBKDF2WithHmacSHA1 Java Equivalent
        $hash = openssl_pbkdf2($key1,$salt1,'256','65536', 'sha1'); 

        $encrypted = openssl_encrypt($data, $method, $hash, OPENSSL_RAW_DATA, $IVbytes);

        return bin2hex($encrypted);
    }else{
        return "String to encrypt, Salt and Key is required.";
    }
}

public function decrypt($data="", $key = NULL, $salt = "") {
    if($key != NULL && $data != "" && $salt != ""){
        $dataEncypted = hex2bin($data);
        $method = "AES-256-CBC";

        //Converting Array to bytes
        $iv = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15];
        $chars = array_map("chr", $iv);
        $IVbytes = join($chars);

        $salt1 = mb_convert_encoding($salt, "UTF-8");//Encoding to UTF-8
        $key1 = mb_convert_encoding($key, "UTF-8");//Encoding to UTF-8

        //SecretKeyFactory Instance of PBKDF2WithHmacSHA1 Java Equivalent
        $hash = openssl_pbkdf2($key1,$salt1,'256','65536', 'sha1'); 

        $decrypted = openssl_decrypt($dataEncypted, $method, $hash, OPENSSL_RAW_DATA, $IVbytes);
        return $decrypted;
    }else{

        return "Encrypted String to decrypt, Salt and Key is required.";

    }
}

}

I am not able to decrypt a string generated using java using this PHP

Update

here is the text and key that i tried for encryption using the above java code

Random generated text (asp_secret)  : DTosv9G179D0cY1985Uh2eF6ND80C95L
Random generated Key used (encKey): VEMwcCYfFpsrXQVIFTDrA/2zP/5PYOY6JC1XEkEcLGSk/klt+HqHzGSr781Yznku
Encrypted string using above java code (enc_asp_secret): zAnTcjmAezfdzrWGixyfwmb8cM0otrsmwJ8+cNDs48Axh9hYgBtCJyeSE9tCvEBz

Answer 1

Since you are interested in the decryption of an encrypted string in which the encryption was done with the Java encryptEK-method and the decryption should be done with the PHP decrypt-method (or vice versa) I ignore the code of the main-method (which isn't very clear to me) and I focus on the porting of the both Java-methods, encryptEK and decrypt, to PHP-methods.

The Java encryptEK-method takes a plain text and a key as byte array, encrypts the plain text using AES (256-ECB) and encodes the encrypted text using Base64 encoding. A possible PHP-counterpart is:

public function encrypt($data = '', $key = NULL) {
    if($key != NULL && $data != ""){
        $method = "AES-256-ECB";
        $encrypted = openssl_encrypt($data, $method, $key, OPENSSL_RAW_DATA);
        $result = base64_encode($encrypted);
        return $result;
    }else{
        return "String to encrypt, Key is required.";
    }
}

Note: The ECB-mode doesn't use an IV.

The Java decrypt-method takes a base64 encoded string, decodes it and then decrypts it. A possible PHP-counterpart is

public function decrypt($data="", $key = NULL) {
    if($key != NULL && $data != ""){
        $method = "AES-256-ECB";
        $dataDecoded = base64_decode($data);
        $decrypted = openssl_decrypt($dataDecoded, $method, $key, OPENSSL_RAW_DATA);
        return $decrypted;
    }else{
        return "Encrypted String to decrypt, Key is required.";
    }
}

The both Java-methods, encodeBase64String and decodeBase64StringTOByte, which use the java.util.Base64-class are not consumed by the Java-methods encryptEK and decrypt. Instead of that, the corresponding methods of the org.apache.commons.codec.binary.Base64-class (e.g. https://commons.apache.org/proper/commons-codec/download_codec.cgi) are consumed. For this reason, I do not take any further notice of both methods.

In the Java reference code no 256bit-AES key is examplarily generated, but a random key is typically generated in the following way:

KEYGEN.init(256);
SecretKey secretKey = KEYGEN.generateKey();
byte[] key = secretKey.getEncoded();

In PHP this is done with

$key = random_bytes(32);

For a mixed encryption/decryption-testing (e.g. Java/PHP) on both sides the same key has to be used. E.g., this key is provided in Java:

byte[] key = "This is a 256 bits = 32 byte key".getBytes(Charsets.UTF_8);

and in PHP:

$key = mb_convert_encoding("This is a 256 bits = 32 byte key", "UTF-8");

Test 1: Encrypt/Decrypt with Java (using a random generated key)

Plain text: The quick brown fox jumps over the lazy dog
Randomly generated key (hex): 20e9c191374b688e74e68ab6c969109e84c5c8e059d84f16f2beb07a7545cbc8
Encrypted text (base64 encoded): ZWOnSYErRxRRtqoVFTLVQMT329pOFHzN1gPDMuiZt0zFpt4n2TF/L54RB21zhVUa
Decrypted text: The quick brown fox jumps over the lazy dog

Test 2: Encrypt/Decrypt with PHP (using a random generated key)

Plain text: The quick brown fox jumps over the lazy dog
Randomly generated key (hex): eecd40c21e2a395f3aa3baeac19bfc8dcee04ea6e07f02dca7069397a487824f
Encrypted text (base64 encoded): 8wjusOED9TTXHjyEqvmGExLATVlvhg3hXEBHQ6Ku3Fos2OrYKbF+4XdO6cD9JJA5
Decrypted text: The quick brown fox jumps over the lazy dog

Possible encryption and decryption portion:

$key = random_bytes(32);
echo bin2hex($key);
$atomAES = new AtomAES();
$encrypt = $atomAES->encrypt("The quick brown fox jumps over the lazy dog", $key);
echo $encrypt; 
$decrypt = $atomAES->decrypt($encrypt, $key);
echo $decrypt;

Test 3: Encrypt with Java/Decrypt with PHP (using the concrete key above)

Plain text: The quick brown fox jumps over the lazy dog
Encrypted text (base64 encoded) with Java: /XjXJc5dNk6p/h2HL8MVmmWG8Vd0Ud2x1QQWwmIQr9OG/PXZ0AzsIIMV1YmvMJho
Decrypted text with PHP: The quick brown fox jumps over the lazy dog

Possible decryption portion:

$key = mb_convert_encoding("This is a 256 bits = 32 byte key", "UTF-8");
$atomAES = new AtomAES();
$decrypt = $atomAES->decrypt("/XjXJc5dNk6p/h2HL8MVmmWG8Vd0Ud2x1QQWwmIQr9OG/PXZ0AzsIIMV1YmvMJho", $key);
echo $decrypt;

Test 4: Encrypt with PHP/Decrypt with Java (using the concrete key above)

Plain text: The quick brown fox jumps over the lazy dog
Encrypted text (base64 encoded) with PHP:  /XjXJc5dNk6p/h2HL8MVmmWG8Vd0Ud2x1QQWwmIQr9OG/PXZ0AzsIIMV1YmvMJho
Decrypted text with Java: The quick brown fox jumps over the lazy dog

Possible encryption portion:

$key = mb_convert_encoding("This is a 256 bits = 32 byte key", "UTF-8");
$atomAES = new AtomAES();
$encrypt = $atomAES->encrypt("The quick brown fox jumps over the lazy dog", $key);
echo $encrypt; 

EDIT:

The counterpart to the code in the main-method is (in combination with your sample):

$encKey = mb_convert_encoding("VEMwcCYfFpsrXQVIFTDrA/2zP/5PYOY6JC1XEkEcLGSk/klt+HqHzGSr781Yznku", "UTF-8");
$asp_secret = mb_convert_encoding("DTosv9G179D0cY1985Uh2eF6ND80C95L", "UTF-8");

atomAES = new AtomAES();
$enc_key = $atomAES->decrypt($encKey, $asp_secret);
$enc_asp_secret = $atomAES->encrypt($asp_secret, base64_decode(base64_encode($enc_key)));
//$enc_asp_secret = $atomAES->encrypt($asp_secret, $enc_key);

echo "asp secret encrypted:\n".mb_convert_encoding($enc_asp_secret, "UTF-8")."\n"; 

Note: The PHP expression base64_decode(base64_encode($enc_key)) is equivalent to $enc_key, thus you can also replace it with the line currently commented out. The only reason I coded it is because it is also coded in the Java code. Here decodeBase64StringTOByte(encodeBase64String(enc_key) is equivalent to enc_key. That's because the one method is the inverse of the other method.

If you run the above code the output is

asp secret encrypted:
zAnTcjmAezfdzrWGixyfwmb8cM0otrsmwJ8+cNDs48Axh9hYgBtCJyeSE9tCvEBz

You can alternatively define a third method of the AtomAES-class:

public function main(){
    $encKey = mb_convert_encoding("VEMwcCYfFpsrXQVIFTDrA/2zP/5PYOY6JC1XEkEcLGSk/klt+HqHzGSr781Yznku", "UTF-8");
    $asp_secret = mb_convert_encoding("DTosv9G179D0cY1985Uh2eF6ND80C95L", "UTF-8");

    $enc_key = $this->decrypt($encKey, $asp_secret);
    $enc_asp_secret = $this->encrypt($asp_secret, base64_decode(base64_encode($enc_key)));
    //$enc_asp_secret = $this->encrypt($asp_secret, $enc_key);

    echo "asp secret encrypted:\n".mb_convert_encoding($enc_asp_secret, "UTF-8")."\n"; 
}

which can be called with

$atomAES = new AtomAES();
$atomAES->main();