[JAVA] 파일 암호화(aes256)_참고용

public class FileAes256Util {
	
    private static String KEY = "9003e5a13d69a78c0d8210cb28b9d0d38e5445568899f637c24bc08241f98ded";
	private static String IV = "024e54561023da13118d16ac21119b8a";
    
	public static byte[] hexStringToByteArray(String s) {
		int len = s.length();
		byte[] data = new byte[len / 2];
		for (int i = 0; i < len; i += 2) {
			data[i / 2] = (byte) ((Character.digit(s.charAt(i), 16) << 4) + Character.digit(s.charAt(i + 1), 16));
		}
		return data;
	}

	public static String aes256Encode(String uploadFile, String FileName) {

    	byte[] _key = hexStringToByteArray(KEY);
		byte[] _iv = hexStringToByteArray(IV);

		InputStream input = null;
		OutputStream output = null;

		SecretKeySpec keyspc = new SecretKeySpec(_key, "AES");
		IvParameterSpec ivSpec = new IvParameterSpec(_iv);

		try {

			Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
			cipher.init(Cipher.ENCRYPT_MODE, keyspc, ivSpec);

			input = new BufferedInputStream(new FileInputStream(uploadFile));
    	    output = new BufferedOutputStream(new FileOutputStream(uploadFile, false));

   	    	byte[] buffer = new byte[1024];
  	    	int read = -1;
        	while ((read = input.read(buffer)) != -1) {
            	output.write(cipher.update(buffer, 0, read));
        	}
        	output.write(cipher.doFinal());
		} catch (Exception e) {
			System.exit(0);
		} finally {
			if (output != null) {
				try {
					output.close();
				} catch (IOException ie) {
                
				}
			}
			if (input != null) {
				try {
					input.close();
				} catch (IOException ie) {
				}
			}
		}
		return uploadFile;
	}
}