AES 256 encrypt / decrypt - JAVA, PHP, Kotlin

ChCrypto.java

package chela.spring.core;

import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.util.Base64;

final public class ChCrypto {
    final static Base64.Encoder encorder = Base64.getEncoder();
    final static Base64.Decoder decorder = Base64.getDecoder();
    static private Cipher cipher(int opmode, String secretKey) throws Exception{
        if(secretKey.length() != 32) throw new RuntimeException("SecretKey length is not 32 chars");
        Cipher c = Cipher.getInstance("AES/CBC/PKCS5Padding");
        SecretKeySpec sk = new SecretKeySpec(secretKey.getBytes(), "AES");
        IvParameterSpec iv = new IvParameterSpec(secretKey.substring(0, 16).getBytes()); //0~16은 서버와 합의!
        c.init(opmode, sk, iv);
        return c;
    }
    static public String encrypt(String str, String secretKey){
        try{
            byte[] encrypted = cipher(Cipher.ENCRYPT_MODE, secretKey).doFinal(str.getBytes("UTF-8"));
            return new String(encorder.encode(encrypted));
        }catch(Exception e){
            return null;
        }
    }
    static public String decrypt(String str, String secretKey){
        try{
            byte[] byteStr = decorder.decode(str.getBytes());
            return new String(cipher(Cipher.DECRYPT_MODE, secretKey).doFinal(byteStr),"UTF-8");
        }catch(Exception e){
            return null;
        }
    }
}

ChCrypto.kt

package chela.spring.core

import java.util.Base64
import javax.crypto.Cipher
import javax.crypto.spec.IvParameterSpec
import javax.crypto.spec.SecretKeySpec

object ChCrypto{
    @JvmStatic fun aesEncrypt(v:String, secretKey:String) = AES256.encrypt(v, secretKey)
    @JvmStatic fun aesDecrypt(v:String, secretKey:String) = AES256.decrypt(v, secretKey)
}

private object AES256{
    private val encorder = Base64.getEncoder()
    private val decorder = Base64.getDecoder()
    private fun cipher(opmode:Int, secretKey:String):Cipher{
        if(secretKey.length != 32) throw RuntimeException("SecretKey length is not 32 chars")
        val c = Cipher.getInstance("AES/CBC/PKCS5Padding")
        val sk = SecretKeySpec(secretKey.toByteArray(Charsets.UTF_8), "AES")
        val iv = IvParameterSpec(secretKey.substring(0, 16).toByteArray(Charsets.UTF_8))
        c.init(opmode, sk, iv)
        return c
    }
    fun encrypt(str:String, secretKey:String):String{
        val encrypted = cipher(Cipher.ENCRYPT_MODE, secretKey).doFinal(str.toByteArray(Charsets.UTF_8))
        return String(encorder.encode(encrypted))
    }
    fun decrypt(str:String, secretKey:String):String{
        val byteStr = decorder.decode(str.toByteArray(Charsets.UTF_8))
        return String(cipher(Cipher.DECRYPT_MODE, secretKey).doFinal(byteStr))
    }
}

ChCryto.php

<?php
final class ChCrytpo{
	static private function checkCryptKey($secretKey){
		if(strlen($secretKey) != 32) throw new Exception('"SecretKey length is not 32 chars"'); //무조건 32byte되도록 로직을 바꿀 수 있음 (2기종간 합의 해야함)
		$iv = substr($secretKey, 0, 16); //IV는 2 기종간 합의하려면 이 규칙을 세울 필요 있음 
		return [$secretKey, $iv];
	}
	static function encrypt($v, $secretKey){
		$k = self::checkCryptKey($secretKey);
		return openssl_encrypt($v, 'aes-256-cbc', $k[0], 0, $k[1]);
	}
	static function decrypt($v, $secretKey){
		$k = self::checkCryptKey($secretKey);
		return openssl_decrypt($v, 'aes-256-cbc', $k[0], 0, $k[1]);
	}
	
}

Thanks for sharing. There's a typo in encorder/decorder

thank you a lot.

Hello !

I improve your encription function, adding random iv.

Here is the result:

import java.util.Base64
import javax.crypto.Cipher
import javax.crypto.spec.IvParameterSpec
import javax.crypto.spec.SecretKeySpec
import java.security.MessageDigest;

object ChCrypto{
@JvmStatic fun aesEncrypt(v:String, secretKey:String) = AES256.encrypt(v, secretKey)
@JvmStatic fun aesDecrypt(v:String, secretKey:String) = AES256.decrypt(v, secretKey)
}

private object AES256{

fun hash(): String {
    val bytes = this.toString().toByteArray()
    val md = MessageDigest.getInstance("SHA-256")
    val digest = md.digest(bytes)
    return digest.fold("", { str, it -> str + "%02x".format(it) })
  }

fun getRandomString(length: Int) : String {
    val charset = "ABCDEFGHIJKLMNOPQRSTUVWXTZabcdefghiklmnopqrstuvwxyz0123456789"
    return (1..length)
        .map { charset.random() }
        .joinToString("")
}

private val encorder = Base64.getEncoder()
private val decorder = Base64.getDecoder()
private fun cipher(opmode:Int, secretKey:String, algo:String):Cipher{
    if(secretKey.length != 32) throw RuntimeException("SecretKey length is not 32 chars")
    val c = Cipher.getInstance("AES/CBC/PKCS5Padding")
    val sk = SecretKeySpec(secretKey.toByteArray(Charsets.UTF_8), "AES")
    val iv = IvParameterSpec(algo.toByteArray(Charsets.UTF_8))
    c.init(opmode, sk, iv)
    return c
}
fun encrypt(str:String, secretKey:String):String{
    val iv = getRandomString(16)
    val encrypted = cipher(Cipher.ENCRYPT_MODE, secretKey, iv).doFinal(str.toByteArray(Charsets.UTF_8))
    return iv.plus(":").plus(String(encorder.encode(encrypted)))
}
fun decrypt(str:String, secretKey:String):String{
    val byteStr = decorder.decode(str.toByteArray(Charsets.UTF_8))
    return String(cipher(Cipher.DECRYPT_MODE, secretKey, "algo").doFinal(byteStr))
}

}
fun main() {

val ket = 'your_key'

print(ChCrypto.aesEncrypt("encriptada - cambiada", key))

}

And here are analog encription and decription in PHP:

function encrypt($data, $password){
$iv = substr(sha1(mt_rand()), 0, 16);
$password = sha1($password);

$salt = sha1(mt_rand());
$saltWithPassword = hash('md5', $password.$salt);

$encrypted = openssl_encrypt(
  "$data", 'aes-256-cbc', "$saltWithPassword", null, $iv
);
$msg_encrypted_bundle = "$iv:$salt:$encrypted";
return $msg_encrypted_bundle;

}

function decrypt($msg_encrypted_bundle, $password){
$password = sha1($password);

$components = explode( ':', $msg_encrypted_bundle );
$iv            = $components[0];
$salt          = hash('md5', $password.$components[1]);
$encrypted_msg = $components[2];

$decrypted_msg = openssl_decrypt(
  $encrypted_msg, 'aes-256-cbc', $salt, null, $iv
);

if ( $decrypted_msg === false )
    return false;
return $decrypted_msg;

}

System.out.println("Thank you!")