Java常见加密解密方式

本文主要介绍一种对称加密和一种单向加密
AES => 对称加密
MD5 => 非对称加密

AES

 * 对称加密* AES（AdvancedEncryption Standard，高级数据加密标准）* 算法支持128位、192位和256位的秘钥长度，加密速度比DES和DESede都快，至今还没有被破解的报道。* 经过验证，目前采用的AES算法能够有效抵御已知的针对DES算法的所有攻击方法，如部分差分攻击、相关秘钥攻击等。* AES算法因秘钥建立时间短、灵敏性好、内存需求低等优点，在各个领域得到广泛的研究与应用。* JDK8支持128位、192位和256位长度的AES秘钥，* * 下面举个JDK8实现AES的128位加密的例子* 其中customKey 是密钥，128位即16字节，  word 就是需要加密的字符串

加密

    public static String encrypt(String customKey, String word) throws Exception {String algorithm = "AES";String transformation = "AES";SecretKey secretKey = new SecretKeySpec(customKey.getBytes(StandardCharsets.UTF_8), "AES");SecretKeySpec secretKeySpec = new SecretKeySpec(secretKey.getEncoded(), algorithm);
//        System.out.println("AES秘钥：" + Base64.getEncoder().encodeToString(secretKey.getEncoded()));Cipher cipher = Cipher.getInstance(transformation);cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec);byte[] encrypt = cipher.doFinal(word.getBytes());
//        System.out.println("AES加密结果：" + Base64.getEncoder().encodeToString(encrypt));return Base64.getEncoder().encodeToString(encrypt);}

解密

public static String decrypt(String customKey ,String word) throws Exception {String algorithm = "AES";String transformation = "AES";SecretKey secretKey = new SecretKeySpec(customKey.getBytes(StandardCharsets.UTF_8), "AES");SecretKeySpec secretKeySpec = new SecretKeySpec(secretKey.getEncoded(), algorithm);
//        System.out.println("AES秘钥：" + Base64.getEncoder().encodeToString(secretKey.getEncoded()));Cipher cipher = Cipher.getInstance(transformation);cipher.init(Cipher.DECRYPT_MODE, secretKeySpec);byte[] decrypt = cipher.doFinal(Base64.getDecoder().decode(word));
//        System.out.println("AES解密结果：" + new String(decrypt));return new String(decrypt);}

演示

    public static void main(String[] args) throws Exception {String word = "admin123";String key = "abcdefgh01234567";String encrypt = encrypt(key, word);String decrypt = decrypt(key, encrypt);System.out.println(encrypt);System.out.println(decrypt);}

MD5

加密

    public static String getMD5(String password){String secretKey = "";try {MessageDigest md = MessageDigest.getInstance("MD5");md.update(password.getBytes());byte b[] = md.digest();int i;StringBuffer buf = new StringBuffer("");for (int offset = 0; offset < b.length; offset++) {i = b[offset];if (i < 0)i += 256;if (i < 16)buf.append("0");buf.append(Integer.toHexString(i));}String result = buf.toString();String md5up32 = result;String md5down32 = result.toUpperCase();String md5up16 = buf.toString().substring(8, 24);String md5down16 = buf.toString().substring(8, 24).toUpperCase();secretKey = md5up32;} catch (NoSuchAlgorithmException e) {e.printStackTrace();}return secretKey;}