When encrypting messages with relatively high security requirements, there are many algorithms. The one I mainly use here is the AES encryption algorithm. Because it is used domestically, it is inevitable to encrypt and decrypt Chinese. During this process, it was discovered that if no processing is done, Chinese garbled characters will easily appear. (Recommended: java video tutorial)

The following are common situations:

1. Chinese garbled characters

Do not encode the password

byte[] decryptResult = decrypt(encryptResult, password);
     System.out.println("解密后：" + new String(decryptResult));

After running

加密前：我是shoneworn
解密后：鎴戞槸shoneworn

2. Encode the text, but convert byte[] into String hastily during the transmission process, String code = new String(bytes); Since the AES encryption algorithm requires encryption Text is a multiple of 16 bits. Therefore, if you handle it this way, various errors will be reported during decryption. Such as the following.

String code = new String(encryptResult);        
byte[] decryptResult = decrypt(code.getBytes(), password);

When AES encrypts, the encrypted data will be converted into a byte array in encoding format, which is the String.getBytes() method. When the getBytes method does not set parameters, the default encoding format of the machine will be used by default. Change to String.getBytes("utf-8") problem solved.

Example of using rsa encryption and decryption:

package com.ailin.test;import java.io.UnsupportedEncodingException;import java.security.InvalidKeyException;import java.security.NoSuchAlgorithmException;import java.security.SecureRandom;import javax.crypto.BadPaddingException;import javax.crypto.Cipher;import javax.crypto.IllegalBlockSizeException;import javax.crypto.KeyGenerator;import javax.crypto.NoSuchPaddingException;import javax.crypto.SecretKey;import javax.crypto.spec.SecretKeySpec;public class AES {    /**
     * 加密
     * 
     * @param content
     *            需要加密的內(nèi)容
     * @param password
     *            加密密碼
     * @return
     */
    public static byte[] encrypt(String content, String password) {        try {
            KeyGenerator kgen = KeyGenerator.getInstance("AES");
            kgen.init(128, new SecureRandom(password.getBytes()));
            SecretKey secretKey = kgen.generateKey();            byte[] enCodeFormat = secretKey.getEncoded();
            SecretKeySpec key = new SecretKeySpec(enCodeFormat, "AES");
            Cipher cipher = Cipher.getInstance("AES");// 創(chuàng)建密碼器
            byte[] byteContent = content.getBytes("utf-8");
            cipher.init(Cipher.ENCRYPT_MODE, key);// 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;
    }    /**
     * 解密
     * 
     * @param content
     *            待解密內(nèi)容
     * @param password
     *            解密密鑰
     * @return
     */
    public static byte[] decrypt(byte[] content, String password) {        try {
            KeyGenerator kgen = KeyGenerator.getInstance("AES");
            kgen.init(128, new SecureRandom(password.getBytes()));
            SecretKey secretKey = kgen.generateKey();            byte[] enCodeFormat = secretKey.getEncoded();
            SecretKeySpec key = new SecretKeySpec(enCodeFormat, "AES");
            Cipher cipher = Cipher.getInstance("AES");// 創(chuàng)建密碼器
            cipher.init(Cipher.DECRYPT_MODE, key);// 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;
    }    /**
     * 將二進(jìn)制轉(zhuǎn)換成16進(jìn)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 = &#39;0&#39; + hex;
            }
            sb.append(hex.toUpperCase());
        }        return sb.toString();
    }    /**
     * 將16進(jìn)制轉(zhuǎn)換為二進(jìn)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;
    }    /**
     * 加密
     *
     * @param content
     *            需要加密的內(nèi)容
     * @param password
     *            加密密碼
     * @return
     */
    public static byte[] encrypt2(String content, String password) {        try {
            SecretKeySpec key = new SecretKeySpec(password.getBytes(), "AES");
            Cipher cipher = Cipher.getInstance("AES/ECB/NoPadding");            byte[] byteContent = content.getBytes("utf-8");
            cipher.init(Cipher.ENCRYPT_MODE, key);// 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;
    }    public static void main(String[] args) throws UnsupportedEncodingException {
        String content = "我是shoneworn";
        String password = "12345678";        // 加密
        System.out.println("加密前：" + content);        byte[] encode = encrypt(content, password);        
        //傳輸過(guò)程,不轉(zhuǎn)成16進(jìn)制的字符串，就等著程序崩潰掉吧
        String code = parseByte2HexStr(encode);
        System.out.println("密文字符串：" + code);        byte[] decode = parseHexStr2Byte(code);        // 解密
        byte[] decryptResult = decrypt(decode, password);
        System.out.println("解密后：" + new String(decryptResult, "UTF-8")); //不轉(zhuǎn)碼會(huì)亂碼            
         }
}

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