Non-Static (Instance) 변수를 활용한 AES 128 BITS ALGORITHM AES/ECB/PKCS7PADDING AND HEX ENCODING

import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;

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public class AES128 {

​
 public static String key = "AAAAAAAAAAAAAAAA";
 
     public static void main(String[] args) {
         String message = "ABCDEFGHIJKLMNOPQRSTUABCDEFGHIJKLMNOPQRSTUABCDEFGHIJKLMNOPQRSTU";
  
         AES128 aes128 = new AES128();
  
         try 
         { 
            String encrypt = aes128.encrypt(message);
            System.out.println("[ORIGIN  STR ]= " + message);
            System.out.println("[ENCRYPT STR ]= " + encrypt);
           
            String decrypt = aes128.decrypt(encrypt);
            System.out.println("[DECRYPT STR ]= " + decrypt);
         } 
         catch (Exception e) 
         {
            e.printStackTrace();
         }
     }
     public byte[] hexToByteArray(String hex) {
        if (hex == null || hex.length() == 0) {
            return null;
        }

        byte[] ba = new byte[hex.length() / 2];
        
        for (int i = 0; i < ba.length; i++) {
            ba[i] = (byte) Integer.parseInt(hex.substring(2 * i, 2 * i + 2), 16);
        }
        
        return ba;
     }
     public String byteArrayToHex(byte[] ba) {
        if (ba == null || ba.length == 0) {
            return null;
        }

        StringBuffer sb = new StringBuffer(ba.length * 2);
        String hexNumber;
        
        for (int x = 0; x < ba.length; x++) {
            hexNumber = "0" + Integer.toHexString(0xff & ba[x]);
            sb.append(hexNumber.substring(hexNumber.length() - 2));
        }
        
        return sb.toString();
     }
     public String encrypt(String message) throws Exception {
  
        AES128 aes128 = new AES128();
  
        SecretKeySpec skeySpec = new SecretKeySpec(key.getBytes(), "AES");

        Cipher cipher = Cipher.getInstance("AES");
        cipher.init(Cipher.ENCRYPT_MODE, skeySpec);

        byte[] encrypted = cipher.doFinal(message.getBytes());
        
        return aes128.byteArrayToHex(encrypted);
     }
     public String decrypt(String encrypted) throws Exception {
  
        AES128 aes128 = new AES128();
  
        SecretKeySpec skeySpec = new SecretKeySpec(key.getBytes(), "AES");

        Cipher cipher = Cipher.getInstance("AES");
        cipher.init(Cipher.DECRYPT_MODE, skeySpec);
        
        byte[] original = cipher.doFinal(aes128.hexToByteArray(encrypted));
      
        String originalString = new String(original);
        
        return originalString;
    }
}

 

/*결과

[ORIGIN  STR ]= ABCDEFGHIJKLMNOPQRSTUABCDEFGHIJKLMNOPQRSTUABCDEFGHIJKLMNOPQRSTU
[ENCRYPT STR ]= 1eb6a5b8559de7cf7936ad108fb1bd2cd323454cfb4097b6bc53e670a51e9067
deaeebd8095ae5a76ebf9797c551bc0ab0ebca77dc7be9dd95452b34e90f845c
[DECRYPT STR ]= ABCDEFGHIJKLMNOPQRSTUABCDEFGHIJKLMNOPQRSTUABCDEFGHIJKLMNOPQRSTU

*/​