자바 랜덤 API 암호화 BASE64 KEY 생성

package egovframework.util;

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

import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.xml.bind.DatatypeConverter;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;

public class RandomAESKeyGen {

​​​​public static String generate(final int keyLen) throws NoSuchAlgorithmException {
​​​​​​​​KeyGenerator keyGen = KeyGenerator.getInstance("AES");
​​​​​​​​keyGen.init(keyLen);
​​​​​​​​SecretKey secretKey = keyGen.generateKey();
​​​​​​​​byte[] encoded = secretKey.getEncoded();
​​​​​​​​return DatatypeConverter.printHexBinary(encoded).toLowerCase();
​​​​}

​​​​public static String generate2(final int keyLen) throws NoSuchAlgorithmException {

​​​​​​​​SecureRandom random = new SecureRandom();
​​​​​​​​byte bytes[] = new byte[keyLen/8];
​​​​​​​​random.nextBytes(bytes);
​​​​​​​​return DatatypeConverter.printHexBinary(bytes).toLowerCase();
​​​​}

​​​​public static String generateBase64(final int keyLen) throws NoSuchAlgorithmException {
​​​​​​​​KeyGenerator keyGen = KeyGenerator.getInstance("AES");
​​​​​​​​keyGen.init(keyLen);
​​​​​​​​SecretKey secretKey = keyGen.generateKey();
​​​​​​​​byte[] encoded = secretKey.getEncoded();
​​​​​​​​String key = DatatypeConverter.printHexBinary(encoded).toLowerCase();
​​​​​​​​byte[] base64Key = Base64.encodeBase64(key.getBytes());
​​​​​​​​return new String(base64Key);
​​​​}

​​​​public static String generate2Base64(final int keyLen) throws NoSuchAlgorithmException {

​​​​​​​​SecureRandom random = new SecureRandom();
​​​​​​​​byte bytes[] = new byte[keyLen/8];
​​​​​​​​random.nextBytes(bytes);
​​​​​​​​String key =  DatatypeConverter.printHexBinary(bytes).toLowerCase();
​​​​​​​​byte[] base64Key = Base64.encodeBase64(key.getBytes());
​​​​​​​​return new String(base64Key);
​​​​}

​​​​public static void main(String[] args) {
​​​​​​​​String key = null;
​​​​​​​​String result="";
​​​​​​​​for(int i=0; i< 5; ++i) {
​​​​​​​​​​​​try {
​​​​​​​​​​​​​​​​key = RandomAESKeyGen.generateBase64(128);

​​​​​​​​​​​​} catch (NoSuchAlgorithmException e) {
​​​​​​​​​​​​​​​​System.out.println("Exception caught");
​​​​​​​​​​​​​​​​e.printStackTrace();
​​​​​​​​​​​​}
​​​​​​​​​​​​System.out.println("KeyGenerator 128 key 순번:[" + i + "]" + key);
​​​​​​​​}
​​​​​​​​System.out.println("==================");

​​​​​​​​for(int i=0; i< 5; ++i) {
​​​​​​​​​​​​try {
​​​​​​​​​​​​​​​​key = RandomAESKeyGen.generateBase64(256);
​​​​​​​​​​​​} catch (NoSuchAlgorithmException e) {
​​​​​​​​​​​​​​​​System.out.println("Exception caught");
​​​​​​​​​​​​​​​​e.printStackTrace();
​​​​​​​​​​​​}
​​​​​​​​​​​​System.out.println("KeyGenerator 256key 순번:[" + i + "]" + key);
​​​​​​​​}
​​​​​​​​System.out.println("==================");

​​​​​​​​for(int i=0; i< 5; ++i) {
​​​​​​​​​​​​try {
​​​​​​​​​​​​​​​​key = RandomAESKeyGen.generate2Base64(128);
​​​​​​​​​​​​} catch (NoSuchAlgorithmException e) {
​​​​​​​​​​​​​​​​System.out.println("Exception caught");
​​​​​​​​​​​​​​​​e.printStackTrace();
​​​​​​​​​​​​}
​​​​​​​​​​​​System.out.println("SecureRandom 128 key 순번:[" + i + "]" + key);
​​​​​​​​}
​​​​​​​​System.out.println("==================");

​​​​​​​​for(int i=0; i< 5; ++i) {
​​​​​​​​​​​​try {
​​​​​​​​​​​​​​​​key = RandomAESKeyGen.generate2Base64(256);
​​​​​​​​​​​​} catch (NoSuchAlgorithmException e) {
​​​​​​​​​​​​​​​​System.out.println("Exception caught");
​​​​​​​​​​​​​​​​e.printStackTrace();
​​​​​​​​​​​​}
​​​​​​​​​​​​System.out.println("SecureRandom 256key 순번:[" + i + "]" + key);
​​​​​​​​}
​​​​}
}