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);
        }
    }
}