AES, SHA256 암 복호화

package co.kr.s3i.common;

import java.io.UnsupportedEncodingException;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.Key;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

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

public class AES256Util {

	private String REAL_KEY = "KEY";

	private String iv;
	private Key keySpec;

	private String SHA256(String key) {
		String SHA = "";
		try {
			MessageDigest sh = MessageDigest.getInstance("SHA-256");
			sh.update(key.getBytes());
			byte byteData[] = sh.digest();
			StringBuffer sb = new StringBuffer();
			for (int i = 0; i < byteData.length; i++) {
				sb.append(Integer.toString((byteData[i] & 0xff) + 0x100, 16).substring(1));
			}
			SHA = sb.toString();

		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
			SHA = null;
		}
		return SHA;
	}

	public AES256Util() throws UnsupportedEncodingException {
		String key = SHA256(REAL_KEY);
		this.iv = key.substring(0, 16);

		byte[] keyBytes = new byte[16];
		byte[] b = key.getBytes("UTF-8");
		int len = b.length;
		if (len > keyBytes.length)
			len = keyBytes.length;
		System.arraycopy(b, 0, keyBytes, 0, len);
		SecretKeySpec keySpec = new SecretKeySpec(keyBytes, "AES");

		this.keySpec = keySpec;
	}

	// 암호화
	public String aesEncode(String str) throws java.io.UnsupportedEncodingException, NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException,
			InvalidAlgorithmParameterException, IllegalBlockSizeException, BadPaddingException {
		
		if(!BaseCode.isAES256_CHECK){
			return str;
		}
		
		Cipher c = Cipher.getInstance("AES/CBC/PKCS5Padding");
		c.init(Cipher.ENCRYPT_MODE, keySpec, new IvParameterSpec(iv.getBytes()));

		byte[] encrypted = c.doFinal(str.getBytes("UTF-8"));
		String enStr = new String(Base64.encodeBase64(encrypted));
		
		return enStr;
	}

	// 복호화
	public String aesDecode(String str) throws java.io.UnsupportedEncodingException, NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException,
			InvalidAlgorithmParameterException, IllegalBlockSizeException, BadPaddingException {
		
		if(!BaseCode.isAES256_CHECK){
			return str;
		}
		
		Cipher c = Cipher.getInstance("AES/CBC/PKCS5Padding");
		c.init(Cipher.DECRYPT_MODE, keySpec, new IvParameterSpec(iv.getBytes("UTF-8")));
		byte[] byteStr = Base64.decodeBase64(str.getBytes());

		return new String(c.doFinal(byteStr), "UTF-8");
	}

}