前言

CBC（Cipher-block chaining），即密码分组链接，是一种较为常用的加密模式。接下来介绍一下Android中实现CBC加解密的具体流程。

导入bcprov.jar

实现CBC加密需要用到bcprov.jar，百度网盘下载地址：

链接：

提取码：ijmz

AESCBCUtil.java

定义一个工具类AESCBCUtil，实现CBC加密、解密等方法：

package com.example.cbc;import java.util.Locale;import javax.crypto.Cipher;import javax.crypto.spec.IvParameterSpec;import javax.crypto.spec.SecretKeySpec;import org.bouncycastle.util.encoders.Base64;public class AESCBCUtil {
       //密码    private static final String key = "aaaabbbbccccdddd";    //iv偏移量    private static final String iv = "0000000000000000";    /**     * 加密：对字符串进行加密，并返回十六进制字符串(hex)     *     * @param encryptStr 需要加密的字符串     * @return 加密后的十六进制字符串(hex)     */    public static String encrypt(String encryptStr,String key,String iv) {
           try {
               IvParameterSpec ivParameterSpec = new IvParameterSpec(iv.getBytes("UTF-8"));            SecretKeySpec skeySpec = new SecretKeySpec(key.getBytes("UTF-8"), "AES");            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");            cipher.init(Cipher.ENCRYPT_MODE, skeySpec, ivParameterSpec);            byte[] encrypted = cipher.doFinal(encryptStr.getBytes());            byte[] encode = Base64.encode(encrypted);            String string = new String(encode);            return string;            //     return byte2HexStr(encrypted);        } catch (Exception ex) {
               ex.printStackTrace();        }        return null;    }    /**     * 解密：对加密后的十六进制字符串(hex)进行解密，并返回字符串     *     * @param encryptedStr 需要解密的，加密后的十六进制字符串     * @return 解密后的字符串     */    public static String decrypt(String encryptedStr,String key,String iv) {
           try {
               IvParameterSpec ivParameterSpec = new IvParameterSpec(iv.getBytes("UTF-8"));            SecretKeySpec skeySpec = new SecretKeySpec(key.getBytes("UTF-8"), "AES");            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS7PADDING");            cipher.init(Cipher.DECRYPT_MODE, skeySpec, ivParameterSpec);            byte[] decode = Base64.decode(encryptedStr);            //  byte[] bytes = hexStr2Bytes(encryptedStr);            byte[] original = cipher.doFinal(decode);            return new String(original);        } catch (Exception ex) {
               ex.printStackTrace();        }        return null;    }    /**     * 十六进制字符串转换为byte[]     *     * @param hexStr 需要转换为byte[]的字符串     * @return 转换后的byte[]     */    public static byte[] hexStr2Bytes(String hexStr) {
           /*对输入值进行规范化整理*/        hexStr = hexStr.trim().replace(" ", "").toUpperCase(Locale.US);        //处理值初始化        int m = 0, n = 0;        int iLen = hexStr.length() / 2; //计算长度        byte[] ret = new byte[iLen]; //分配存储空间        for (int i = 0; i < iLen; i++) {
               m = i * 2 + 1;            n = m + 1;            ret[i] = (byte) (Integer.decode("0x" + hexStr.substring(i * 2, m) + hexStr.substring(m, n)) & 0xFF);        }        return ret;    }    /**     * byte[]转换为十六进制字符串     *     * @param bytes 需要转换为字符串的byte[]     * @return 转换后的十六进制字符串     */    public static String byte2HexStr(byte[] bytes) {
           String hs = "";        String stmp = "";        for (int n = 0; n < bytes.length; n++) {
               stmp = (Integer.toHexString(bytes[n] & 0XFF));            if (stmp.length() == 1)                hs = hs + "0" + stmp;            else                hs = hs + stmp;        }        return hs;    }}

MainActivity.java

MainActivity.java中调用工具类AESCBCUtil的方法，进行测试数据的加解密：

package com.example.cbc;import androidx.appcompat.app.AppCompatActivity;import android.os.Bundle;import android.util.Log;public class MainActivity extends AppCompatActivity {
       private String key = "aaaabbbbccccdddd";//密钥，必须16位    private String content1 = "fgsrgreatrt";//待加密内容    private String content2 = "AyKRIVDV9PSQ9gOJLQG/bw==";//待解密内容    private String iv = "0000000000000000";//偏移量    @Override    protected void onCreate(Bundle savedInstanceState) {
           super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        Log.d("Jason", "encode result:" + AESCBCUtil.encrypt(content1, key, iv));        Log.d("Jason", "decode result:" + AESCBCUtil.decrypt(content2, key, iv));    }}