Java常见的两种加密方式

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;
    }

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