翻译I have been trying to decrypt a string using AES-128 CBC which was originally crypted using JAVA AES encryption. In java PKCS7 padding is used. And I have tried to encrypt and decrypt using similar PHP code. But I am getting different result.
My Java code
import java.security.MessageDigest; import java.security.spec.AlgorithmParameterSpec; import javax.crypto.Cipher; import javax.crypto.spec.IvParameterSpec; import javax.crypto.spec.SecretKeySpec; import android.util.Base64; /** * @author vipin.cb , vipin.cb@experionglobal.com
* Sep 27, 2013, 5:18:34 PM
* Package:- com.veebow.util
* Project:- Veebow * */ public class AESCrypt { private final Cipher cipher; private final SecretKeySpec key; private AlgorithmParameterSpec spec; public static final String SEED_16_CHARACTER = "U1MjU1M0FDOUZ.Qz"; public AESCrypt() throws Exception { // hash password with SHA-256 and crop the output to 128-bit for key MessageDigest digest = MessageDigest.getInstance("SHA-256"); digest.update(SEED_16_CHARACTER.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; } }
And the equivalent PHP code I am using.
key = hash('sha256', $this->key, true); } function encrypt($str) { $iv = $this->iv; $td = mcrypt_module_open(MCRYPT_RIJNDAEL_128, '', MCRYPT_MODE_CBC, ''); mcrypt_generic_init($td, $this->key, $iv); $block = mcrypt_get_block_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_CBC); $pad = $block - (strlen($str) % $block); $str .= str_repeat(chr($pad), $pad); $encrypted = mcrypt_generic($td, $str); mcrypt_generic_deinit($td); mcrypt_module_close($td); return base64_encode($encrypted); } function decrypt($code) { $iv = $this->iv; $td = mcrypt_module_open('rijndael-128', '', 'cbc', ''); mcrypt_generic_init($td, $this->key, $iv); $str = mdecrypt_generic($td, base64_decode($code)); $block = mcrypt_get_block_size('rijndael-128', 'cbc'); mcrypt_generic_deinit($td); mcrypt_module_close($td); return $str; //return $this->strippadding($str); } /* For PKCS7 padding */ private function addpadding($string, $blocksize = 16) { $len = strlen($string); $pad = $blocksize - ($len % $blocksize); $string .= str_repeat(chr($pad), $pad); return $string; } private function strippadding($string) { $slast = ord(substr($string, -1)); $slastc = chr($slast); $pcheck = substr($string, -$slast); if (preg_match("/$slastc{" . $slast . "}/", $string)) { $string = substr($string, 0, strlen($string) - $slast); return $string; } else { return false; } } } $encryption = new MCrypt(); echo $encryption->encrypt('123456') . "
"; echo $encryption->decrypt('tpyxISJ83dqEs3uw8bN/+w==');In Java
Plain text = 123456
Cipher text = tpyxISJ83dqEs3uw8bN/+w==
In PHP
Plain text = 123456
Cipher text = IErqfTCktrnmWndOpq3pnQ==
When I tried to decrpt the Java encrypted text "tpyxISJ83dqEs3uw8bN/+w==" using PHP decryption I am getting an empty array if I removed the padding . Without removing the padding I am getting "::::::::::"
I think there is some mistake with the IV bytes used in PHP and Java Can anyone help me on this. I have tried many combinations . Still no result. I am very new to Java concepts.
------Solution-------
I have modified my php class according to the comments given by owlstead. may be there is a better way. I am posting it here so that someone may find it helpful in future and your comments are welcome for further improvement.
key = hash('sha256', $this->key, true); //echo $this->key.'
'; } function encrypt($str) { $td = mcrypt_module_open(MCRYPT_RIJNDAEL_128, '', MCRYPT_MODE_CBC, ''); mcrypt_generic_init($td, $this->key, $this->hexToStr($this->hex_iv)); $block = mcrypt_get_block_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_CBC); $pad = $block - (strlen($str) % $block); $str .= str_repeat(chr($pad), $pad); $encrypted = mcrypt_generic($td, $str); mcrypt_generic_deinit($td); mcrypt_module_close($td); return base64_encode($encrypted); } function decrypt($code) { $td = mcrypt_module_open(MCRYPT_RIJNDAEL_128, '', MCRYPT_MODE_CBC, ''); mcrypt_generic_init($td, $this->key, $this->hexToStr($this->hex_iv)); $str = mdecrypt_generic($td, base64_decode($code)); $block = mcrypt_get_block_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_CBC); mcrypt_generic_deinit($td); mcrypt_module_close($td); return $this->strippadding($str); } /* For PKCS7 padding */ private function addpadding($string, $blocksize = 16) { $len = strlen($string); $pad = $blocksize - ($len % $blocksize); $string .= str_repeat(chr($pad), $pad); return $string; } private function strippadding($string) { $slast = ord(substr($string, -1)); $slastc = chr($slast); $pcheck = substr($string, -$slast); if (preg_match("/$slastc{" . $slast . "}/", $string)) { $string = substr($string, 0, strlen($string) - $slast); return $string; } else { return false; } } function hexToStr($hex) { $string=''; for ($i=0; $i encrypt('123456') . "
"; echo $encryption->decrypt('tpyxISJ83dqEs3uw8bN/+w==');