加密方式-对称加密(AES)

对称加密中AES是比较常用，DES因为安全性比不上AES已经用的较少
对称加密:是指加密解密都是一个密钥，通过改密钥加密，也通过它解密。

1.加密

/**
 * 加密
 * 
 * @param content 需要加密的内容
 * @param key 密钥
 * @return
 */
	public static byte[] encrypt(String content, String key) {
		try {
			KeyGenerator kgen = KeyGenerator.getInstance("AES");
			kgen.init(128, new SecureRandom(key.getBytes()));
			SecretKey secretKey = kgen.generateKey();
			byte[] enCodeFormat = secretKey.getEncoded();
			SecretKeySpec keys = new SecretKeySpec(enCodeFormat, "AES");
			Cipher cipher = Cipher.getInstance("AES");//创建密码器
			byte[] byteContent = content.getBytes("utf-8");
			cipher.init(Cipher.ENCRYPT_MODE, keys);// 初始化
			byte[] result = cipher.doFinal(byteContent);
			return result; // 加密
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		} catch (NoSuchPaddingException e) {
			e.printStackTrace();
		} catch (InvalidKeyException e) {
			e.printStackTrace();
		} catch (UnsupportedEncodingException e) {
			e.printStackTrace();
		} catch (IllegalBlockSizeException e) {
			e.printStackTrace();
		} catch (BadPaddingException e) {
			e.printStackTrace();
		}
		return null;
	}

2.解密

/**
 * 解密
 * 
 * @param content 待解密内容
 * @param key 解密密钥
 * @return
 */
	public static byte[] decrypt(byte[] content, String key) {
		try {
			KeyGenerator kgen = KeyGenerator.getInstance("AES");
			kgen.init(128, new SecureRandom(key.getBytes()));
			SecretKey secretKey = kgen.generateKey();
			byte[] enCodeFormat = secretKey.getEncoded();
			SecretKeySpec keys = new SecretKeySpec(enCodeFormat, "AES");
			Cipher cipher = Cipher.getInstance("AES");//创建密码器
			cipher.init(Cipher.DECRYPT_MODE, keys);// 初始化
			byte[] result = cipher.doFinal(content);
			return result; // 加密
		} catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		} catch (NoSuchPaddingException e) {
			e.printStackTrace();
		} catch (InvalidKeyException e) {
			e.printStackTrace();
		} catch (IllegalBlockSizeException e) {
			e.printStackTrace();
		} catch (BadPaddingException e) {
			e.printStackTrace();
		}
		return null;
	}

3.测试

//下面提供两种方式(原来避免转字符串乱码)
	

 1. 通过Base64(强烈推荐)来转
		 org.apache.commons.codec.binary.Base64
 
	 	public static void main(String[] args) {
		
			//1.字符串经过加密得到byte数组
			String content = "my name is libra_ts";
			String key = "1234567812345678";
			byte[] result = encrypt(content, key);
			
			//2.将byte数组用base64转码成字符串
			String strs = Base64.encodeBase64String(result);
			
			//3.传输(我这里直接打印了，项目中一般是进行网络传输)
			System.out.println("==经过加密和BASE64转码后=="+ strs);
			
			//4.将字符串用base64解码成byte数组
			byte[]b1 = Base64.decodeBase64(strs);
			
			//5.解密
			byte[]j1 = decrypt(b1, key);
			
			//6.输出加密之前的内容
			System.out.println(new String(j1));
		
		}


 2. 通过进制转换
	/**
	 * 将二进制转换成16进制
	 * 
	 * @param buf
	 * @return
	 */
	public static String parseByte2HexStr(byte buf[]) {
		StringBuffer sb = new StringBuffer();
		for (int i = 0; i < buf.length; i++) {
			String hex = Integer.toHexString(buf[i] & 0xFF);
			if (hex.length() == 1) {
				hex = '0' + hex;
			}
			sb.append(hex.toUpperCase());
		}
		return sb.toString();
	}

	/**
	 * 将16进制转换为二进制
	 * 
	 * @param hexStr
	 * @return
	 */
	public static byte[] parseHexStr2Byte(String hexStr) {
		if (hexStr.length() < 1) {
			return null;
		}
		byte[] result = new byte[hexStr.length() / 2];
		for (int i = 0; i < hexStr.length() / 2; i++) {
			int high = Integer.parseInt(hexStr.substring(i * 2, i * 2 + 1), 16);
			int low = Integer.parseInt(hexStr.substring(i * 2 + 1, i * 2 + 2), 16);
			result[i] = (byte) (high * 16 + low);
		}
		return result;
	}
	

	public static void main(String[] args) {
		String content = "name=\"libra_ts\"";
		String key = "FTGYHUJKML56SYTWsddd=8n2ndsn3SE6Bnh";
		
		byte[] result = encrypt(content, key);
		// 二进制转16进制
		String encryptResultStr = parseByte2HexStr(result); 
		System.out.println("==加密后==" + new String(results));
		
		// 16进制转二进制
		byte[] decryptFrom = parseHexStr2Byte(encryptResultStr);
		byte[] results = decrypt(decryptFrom, key);
		System.out.println("==解密后==" + new String(results));
	}

因为加密后的byte数组是不能强制转换成字符串的，也就是说字符串和byte数组在这种情况下不是互逆的；要避免这种情况，我们需要做一些修改，推荐采用Base64转码，也可以考虑将二进制数据转换成十六进制