java 实现 AES/CBC/PKCS7Padding 加密解密

home 编辑时间 2019/04/26

## 需求
java 实现 AES/CBC/PKCS7Padding 加密 解密
由于java原生只支持到PKCS5Padding
需要引入第三方依赖支持
参考：[https://www.cnblogs.com/chen-lhx/p/6233954.html](https://www.cnblogs.com/chen-lhx/p/6233954.html)

## 实现
引入maven
```xml
<dependency>
    <groupId>org.bouncycastle</groupId>
    <artifactId>bcprov-jdk15on</artifactId>
    <version>1.57</version>
</dependency>
```

java工具类
```java
package test

import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.util.Arrays;
import org.bouncycastle.util.encoders.Base64;

import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.security.Key;
import java.security.Security;

public class AESUtils {

private static final String KEY_ALGORITHM = "AES";
    private static final String ALGORITHM_STR = "AES/CBC/PKCS7Padding";
    private static Key key;
    private static Cipher cipher;

private static void init(byte[] keyBytes) {
        // 如果密钥不足16位，那么就补足.  这个if 中的内容很重要
        int base = 16;
        if (keyBytes.length % base != 0) {
            int groups = keyBytes.length / base + (keyBytes.length % base != 0 ? 1 : 0);
            byte[] temp = new byte[groups * base];
            Arrays.fill(temp, (byte) 0);
            System.arraycopy(keyBytes, 0, temp, 0, keyBytes.length);
            keyBytes = temp;
        }
        // 初始化
        Security.addProvider(new BouncyCastleProvider());
        // 转化成JAVA的密钥格式
        key = new SecretKeySpec(keyBytes, KEY_ALGORITHM);
        try {
            // 初始化cipher
            cipher = Cipher.getInstance(ALGORITHM_STR, "BC");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

/**
     * 加密方法
     *
     * @param decryptedData 要加密的字符串
     * @param keyBytes      加密密钥
     * @param ivs           自定义对称解密算法初始向量
     * @return
     */
    public static byte[] encryptOfDiyIV(byte[] decryptedData, byte[] keyBytes, byte[] ivs) {
        byte[] encryptedText = null;
        init(keyBytes);
        try {
            cipher.init(Cipher.ENCRYPT_MODE, key, new IvParameterSpec(ivs));
            encryptedText = cipher.doFinal(decryptedData);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return encryptedText;
    }

/**
     * 解密方法
     *
     * @param encryptedData 要解密的字符串
     * @param keyBytes      解密密钥
     * @param ivs           自定义对称解密算法初始向量 iv
     * @return 解密后的字节数组
     */
    private static byte[] decryptOfDiyIV(byte[] encryptedData, byte[] keyBytes, byte[] ivs) {
        byte[] encryptedText = null;
        init(keyBytes);
        try {
            cipher.init(Cipher.DECRYPT_MODE, key, new IvParameterSpec(ivs));
            encryptedText = cipher.doFinal(encryptedData);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return encryptedText;
    }

public static String decryptData(String encryptDataB64, String sessionKeyB64, String ivB64) {
        return new String(
                decryptOfDiyIV(
                        Base64.decode(encryptDataB64),
                        Base64.decode(sessionKeyB64),
                        Base64.decode(ivB64)
                )
        );
    }

public static String encryptData(String encryptDataB64, String sessionKeyB64, String ivB64) {
        return new String(Base64.encode(
                encryptOfDiyIV(
                        Base64.decode(encryptDataB64),
                        Base64.decode(sessionKeyB64),
                        Base64.decode(ivB64)
                )
        ));
    }

public static void main(String[] args) {
        String iv = "1234432112344444";
        String key = "sadhowadaskd123sxdaj122sa12";
        String string = "!@#$测试1234asdvcz";

System.out.println("原文:" + string);
        String code = encryptData(
                new String(Base64.encode(string.getBytes()))
                , new String(Base64.encode(key.getBytes()))
                , new String(Base64.encode(iv.getBytes()))
        );
        System.out.println("密文:" + code);
        String result = decryptData(
                code
                , new String(Base64.encode(key.getBytes()))
                , new String(Base64.encode(iv.getBytes()))
        );
        System.out.println("解密:" + result);
    }

}
```

## 运行结果
```shell
原文:!@#$测试1234asdvcz
密文:xQzhVGWn2DSb+D1gU+X8+2+gX0d09exSebGOrGJxT2c=
解密:!@#$测试1234asdvcz
```

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