java实现AES密钥生成

转自： https://www.jb51.net/article/102128.htm

import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
public class Test {
  public static void main(String[] args) {
    getKey();
    getKeyByPass();
  }
  /**
  * 随机生成秘钥
  */
  public static void getKey() {
    try {
      KeyGenerator kg = KeyGenerator.getInstance("AES");
      kg.init(128);
      //要生成多少位，只需要修改这里即可128, 192或256
      SecretKey sk = kg.generateKey();
      byte[] b = sk.getEncoded();
      String s = byteToHexString(b);
      System.out.println(s);
      System.out.println("十六进制密钥长度为"+s.length());
      System.out.println("二进制密钥的长度为"+s.length()*4);
    }
    catch (NoSuchAlgorithmException e) {
      e.printStackTrace();
      System.out.println("没有此算法。");
    }
  }
  /**
  * 使用指定的字符串生成秘钥
  */
  public static void getKeyByPass() {
    //生成秘钥
    String password="testkey";
    try {
      KeyGenerator kg = KeyGenerator.getInstance("AES");
      // kg.init(128);//要生成多少位，只需要修改这里即可128, 192或256
      //SecureRandom是生成安全随机数序列，password.getBytes()是种子，只要种子相同，序列就一样，所以生成的秘钥就一样。
      kg.init(128, new SecureRandom(password.getBytes()));
      SecretKey sk = kg.generateKey();
      byte[] b = sk.getEncoded();
      String s = byteToHexString(b);
      System.out.println(s);
      System.out.println("十六进制密钥长度为"+s.length());
      System.out.println("二进制密钥的长度为"+s.length()*4);
    }
    catch (NoSuchAlgorithmException e) {
      e.printStackTrace();
      System.out.println("没有此算法。");
    }
  }
  /**
  * byte数组转化为16进制字符串
  * @param bytes
  * @return
  */
  public static String byteToHexString(byte[] bytes) {
    StringBuffer sb = new StringBuffer();
    for (int i = 0; i < bytes.length; i++) {
      String strHex=Integer.toHexString(bytes[i]);
      if(strHex.length() > 3) {
        sb.append(strHex.substring(6));
      } else {
        if(strHex.length() < 2) {
          sb.append("0" + strHex);
        } else {
          sb.append(strHex);
        }
      }
    }
    return sb.toString();
  }
}