java加密算法之AES小记

jce中提供了加解密的api:

1、首先应该明白AES是基于数据块的加密方式，也就是说，每次处理的数据是一块（16字节），当数据不是16字节的倍数时填充，这就是所谓的分组密码（区别于基于比特位的流密码），16字节是分组长度

AES支持五种模式：CBC，CFB，ECB，OFB，PCBC，

jce中实现了三种补码方式：NoPadding，PKCS5Padding，ISO10126Padding;不支持SSL3Padding,不支持“NONE”模式。

ECB：是一种基础的加密方式，密文被分割成分组长度相等的块（不足补齐），然后单独一个个加密，一个个输出组成密文。
CBC：是一种循环模式，前一个分组的密文和当前分组的明文异或操作后再加密，这样做的目的是增强破解难度。
CFB/OFB实际上是一种反馈模式，目的也是增强破解的难度。
ECB和CBC的加密结果是不一样的，两者的模式不同，而且CBC会在第一个密码块运算时加入一个初始化向量。

算法/模式/填充                    16字节加密后数据长度         不满16字节加密后长度

AES/CBC/NoPadding                  16                         不支持
AES/CBC/PKCS5Padding             32                         16
AES/CBC/ISO10126Padding        32                          16
AES/CFB/NoPadding                    16                          原始数据长度
AES/CFB/PKCS5Padding              32                          16
AES/CFB/ISO10126Padding         32                          16
AES/ECB/NoPadding                    16                          不支持
AES/ECB/PKCS5Padding              32                          16
AES/ECB/ISO10126Padding         32                          16
AES/OFB/NoPadding                     16                          原始数据长度
AES/OFB/PKCS5Padding               32                          16
AES/OFB/ISO10126Padding          32                          16
AES/PCBC/NoPadding                   16                          不支持
AES/PCBC/PKCS5Padding             32                          16
AES/PCBC/ISO10126Padding        32                          16
可 以看到，在原始数据长度为16的整数倍时，假如原始数据长度等于16*n，则使用NoPadding时加密后数据长度等于16*n，其它情况下加密数据长 度等于16*(n+1)。在不足16的整数倍的情况下，假如原始数据长度等于16*n+m[其中m小于16]，除了NoPadding填充之外的任何方 式，加密数据长度都等于16*(n+1)；NoPadding填充情况下，CBC、ECB和PCBC三种模式是不支持的，CFB、OFB两种模式下则加密 数据长度等于原始数据长度。 

Demo:

import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class AESCoder {
    
    private static final Logger log=LoggerFactory.getLogger(AESCoder.class);
    
    /**
     * 加密
     * hexStr和hexKey都须为16进制表示的字符串
     * 加密后返回16进制表示的字符串*/
    public static String ecbEnc(String hexStr, String hexKey){
        String rs=null;
        try {
            byte[] inBytes = HexUtil.hexToBytes(hexStr);            
            byte[] keyBytes = HexUtil.hexToBytes(hexKey);
            SecretKeySpec skeySpec = new SecretKeySpec(keyBytes, "AES");
            Cipher cipher = Cipher.getInstance("AES/ECB/NoPadding");// "算法/模式/补码方式"
            cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
            byte[] encrypted = cipher.doFinal(inBytes);            
            rs=HexUtil.bytesToHex(encrypted);
        } catch (Exception e) {
            log.error("加密异常",e);
            log.error("输入参数为hexStr：{},hexKey:{}",hexStr,hexKey);
        }
        return rs;
    }
    
    /**
     * 解密
     * hexStr和hexKey都须为16进制
     * 加密后返回16进制的字符串*/
    public static String ecbDec(String hexStr,String hexKey){
        String rs=null;
        try {
            byte[] outBytes = HexUtil.hexToBytes(hexStr);
            byte[] keyBytes = HexUtil.hexToBytes(hexKey);
            SecretKeySpec skeySpec = new SecretKeySpec(keyBytes, "AES");
            Cipher cipher = Cipher.getInstance("AES/ECB/NoPadding");// "算法/模式/补码方式"
            cipher.init(Cipher.DECRYPT_MODE, skeySpec);
            byte[] decBytes = cipher.doFinal(outBytes);
            rs=HexUtil.bytesToHex(decBytes);
        } catch (Exception e) {
            log.error("解密异常",e);
            log.error("输入参数为hexStr：{},hexKey:{}",hexStr,hexKey);
        }
        return rs;
    }

}

public class HexUtil {
    
    /**
     * 将普通字符串用16进制描述
     * 如"WAZX-B55SY6-S6DT5" 描述为："57415a582d4235355359362d5336445435"
     * */
    public static String strToHex(String str){
         byte[] bytes = str.getBytes(); 
         return bytesToHex(bytes);
    }
    
    /**将16进制描述的字符串还原为普通字符串
     * 如"57415a582d4235355359362d5336445435" 还原为："WAZX-B55SY6-S6DT5"
     * */
    public static String hexToStr(String hex){
        byte[] bytes=hexToBytes(hex);
        return new String(bytes);
    }
    
    
    /**16进制转byte[]*/
    public static byte[] hexToBytes(String hex){
        int length = hex.length() / 2;
        byte[] bytes=new byte[length];
        for(int i=0;i<length;i++){
            String tempStr=hex.substring(2*i, 2*i+2);//byte:8bit=4bit+4bit=十六进制位+十六进制位
            bytes[i]=(byte) Integer.parseInt(tempStr, 16);
        }
        return bytes;
    }
    
    /**byte[]转16进制*/
    public static String bytesToHex(byte[] bytes){
        StringBuilder sb=new StringBuilder();
        for(int i=0;i<bytes.length;i++){
            int tempI=bytes[i] & 0xFF;//byte:8bit,int:32bit;高位相与.
            String str = Integer.toHexString(tempI);
            if(str.length()<2){
                sb.append(0).append(str);//长度不足两位，补齐：如16进制的d,用0d表示。
            }else{
                sb.append(str);
            }
        }
        return sb.toString();
    }

}

public class AESTest {
    
    private static String key="2b7e151628aed2a6abf7158809cf4f3c";
    
    @Test
    public void test_all(){
        String enOri="000000000000000WAZX-B55SY6-S6DT5";
        String enHex=HexUtil.strToHex(enOri);
        String enRS=AESCoder.ecbEnc(enHex,key);
        System.out.println("加密结果为："+enRS);
        
        String deHex="7312560ccb30ad9b445ee94b426c8a2bdf75d11ded50f053568ec08bf3f9be04";
        String deRS=AESCoder.ecbDec(deHex,key);
        String deOri=HexUtil.hexToStr(deRS);
        System.out.println("解密结果为："+deOri);
    }
    
    
    @Test
    public void test_enc(){
        String enStr ="6bc1bee22e409f96e93d7e117393172a";        
        String enRS=AESCoder.ecbEnc(enStr,key);        
        System.out.println(enRS);
    }
    
    @Test
    public void test_dec(){
        String deStr ="3ad77bb40d7a3660a89ecaf32466ef97";        
        String enRS=AESCoder.ecbDec(deStr,key);        
        System.out.println(enRS);

    }
    
    
    
    /**
     * 和后台联调时使用
     * 该函数用于讲16进制数组转成String
     * 如密钥key为
     * uint8_t key[] = 
     *         {0x2b, 0x7e, 0x15, 0x16, 0x28, 0xae, 0xd2, 0xa6, 
     *          0xab, 0xf7, 0x15, 0x88, 0x09, 0xcf, 0x4f, 0x3c}
     * 则格式化之后为"2b7e151628aed2a6abf7158809cf4f3c"
     * */
    public static String convertStr(String hexStr) {
        String[] kStrs = hexStr.split(",");
        String[] keyStrs = new String[kStrs.length];
        for (int i = 0; i < kStrs.length; i++) {
            String str = kStrs[i].trim().substring(2);
            keyStrs[i] = str;
        }
        StringBuffer sb = new StringBuffer();
        for (String str : keyStrs) {
            sb.append(str);
        }
        return sb.toString().toUpperCase();
    }

}

AESTest运行结果：

加密结果为：7312560ccb30ad9b445ee94b426c8a2bdf75d11ded50f053568ec08bf3f9be04
解密结果为：000000000000000WAZX-B55SY6-S6DT5

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--------------------------------------------------------------此外，还有另外一个写法-----------------------------------------------------------------------------------------

---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.spec.SecretKeySpec;

public class AESHelper {

    public static String encrypt(String content, String pwd,String charSet) {
        try {
            byte[] byteContent = content.getBytes(charSet);

            KeyGenerator kgen = KeyGenerator.getInstance("AES");
            kgen.init(128, new SecureRandom(pwd.getBytes()));

            Cipher cipher = Cipher.getInstance("AES");
            cipher.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(kgen.generateKey().getEncoded(), "AES"));

            byte[] buf = cipher.doFinal(byteContent);

            //byte[]转16进制
            StringBuffer sb = new StringBuffer();
            for (int i = 0; i < buf.length; i++) {
                String hex = Integer.toHexString(buf[i] & 0xFF);
                if (hex.length() == 1) {
                    hex = '0' + hex;
                }
                sb.append(hex.toUpperCase());
            }
            return sb.toString();
            
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    /***
     * 
     * @param content 16进制的字符串
     * @param pwd
     * @param charSet
     * @return
     */
    public static String decrypt(String content, String pwd,String charSet) {
        try {
            byte[] byteContent = new byte[content.length() / 2];
            if (content.length() < 1){
                return null;
            }
            //将16进制转换为二进制
            for (int i = 0; i < content.length() / 2; i++) {
                int high = Integer.parseInt(content.substring(i * 2, i * 2 + 1), 16);
                int low = Integer.parseInt(content.substring(i * 2 + 1, i * 2 + 2), 16);
                byteContent[i] = (byte) (high * 16 + low);
            }
            
            KeyGenerator kgen = KeyGenerator.getInstance("AES");
            kgen.init(128, new SecureRandom(pwd.getBytes()));

            Cipher cipher = Cipher.getInstance("AES");
            cipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(kgen.generateKey().getEncoded(), "AES"));

            byte[] buf = cipher.doFinal(byteContent);
            return new String(buf,charSet);
            
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    public static void main(String[] args) {
        String layer = AESHelper.encrypt("编程ABCDefgh~！@#$%^&*()|'?>.<;", "123","utf-8");
        System.out.println(layer);
        String plain = AESHelper.decrypt(layer,"123","utf-8");
        System.out.println(plain);
    }

}

 据说要加上要两句话，不然，跨操作系统加解密可能有问题：

SecureRandom secureRandom=SecureRandom.getInstance("SHA1PRNG");
secureRandom.setSeed(pwd.getBytes());

最终写法：

import java.security.Key;
import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;

public class AESHelper {

    public static String encrypt(String content) {
        return encrypt(content, null, "utf-8");
    }

    /***
     * 加密
     * 
     * @param plain
     * @param keySeed
     * @param charSet
     * @return 输出密文 16进制
     */
    public static String encrypt(String plain, String keySeed, String charSet) {
        try {
            byte[] byteContent = plain.getBytes(charSet);
            Cipher cipher = Cipher.getInstance("AES");
            cipher.init(Cipher.ENCRYPT_MODE, getKey(keySeed));

            byte[] buf = cipher.doFinal(byteContent);

            // byte[]转16进制
            StringBuffer sb = new StringBuffer();
            for (int i = 0; i < buf.length; i++) {
                String hex = Integer.toHexString(buf[i] & 0xFF);
                if (hex.length() == 1) {
                    hex = '0' + hex;
                }
                sb.append(hex.toUpperCase());
            }
            return sb.toString();

        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    public static String decrypt(String content) {
        return decrypt(content, null, "utf-8");
    }

    /***
     * 解密 输入16进制的字符串
     * 
     * @param layer
     * @param keySeed
     * @param charSet
     * @return 原文
     */
    public static String decrypt(String layer, String keySeed, String charSet) {
        try {
            byte[] byteContent = new byte[layer.length() / 2];
            if (layer.length() < 1) {
                return null;
            }
            // 将16进制转换为二进制
            for (int i = 0; i < layer.length() / 2; i++) {
                int high = Integer.parseInt(layer.substring(i * 2, i * 2 + 1), 16);
                int low = Integer.parseInt(layer.substring(i * 2 + 1, i * 2 + 2), 16);
                byteContent[i] = (byte) (high * 16 + low);
            }

            Cipher cipher = Cipher.getInstance("AES");
            cipher.init(Cipher.DECRYPT_MODE, getKey(keySeed));

            byte[] buf = cipher.doFinal(byteContent);
            return new String(buf, charSet);

        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    public static Key getKey(String keySeed) {
        if (keySeed == null) {
            keySeed = System.getenv("AES_SYS_KEY");
        }
        if (keySeed == null) {
            keySeed = System.getProperty("AES_SYS_KEY");
        }
        if (keySeed == null || keySeed.trim().length() == 0) {
            keySeed = "abcd1234!@#$";// 默认种子
        }
        try {
            SecureRandom secureRandom = SecureRandom.getInstance("SHA1PRNG");
            secureRandom.setSeed(keySeed.getBytes());
            KeyGenerator generator = KeyGenerator.getInstance("AES");
            generator.init(secureRandom);
            return generator.generateKey();
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

    public static void main(String[] args) {
        if(null==args||args.length==0){
            args=new String[1];
            args[0]="编程ABCDefgh~！@#$%^&*()|'?>.<;1234567823401";
        }
        String layer = AESHelper.encrypt(args[0]);
        System.out.println("密文："+layer);
        String plain = AESHelper.decrypt(layer);
        System.out.println("原文："+plain);
    }

}

 linux 运行该方法：

　　

[zhangbin@WEB01 test]$ java AESHelper "jwe223489430214aefhasduf3423"
密文：49336565BD95CB2E70297F4F89DEE2D37EA6A7C14A320194848CF17E930B1DB5
原文：jwe223489430214aefhasduf3423