加密与解密

//AES 高级加密标准 Advanced Encryption Standard 的缩写
public  class JiamiActivity extends AppCompatActivity {    private Button jiaMi;    private Button jieMi;    private EditText editText;    public static SecretKeySpec AESKeySpec;//大小    private Button jiaMi2;    private byte[] bytes2;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_jiami);        initView();    }    private void initView() {        jiaMi = (Button) findViewById(R.id.jiamiId);        jiaMi2 = (Button) findViewById(R.id.jiamiId2);        jieMi = (Button) findViewById(R.id.jiemiId);        editText = (EditText) findViewById(R.id.etTextId);        jiaMi.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View view) {                try {                    testGenerateAESKey(128);                } catch (Exception e) {                    e.printStackTrace();                }            }        });        jiaMi2.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View view) {                try {                    testGenerateAESKey(256);                } catch (Exception e) {                    e.printStackTrace();                }            }        });    }    //测试生成的Key    public  void testGenerateAESKey(int keySize) throws Exception {        String str=editText.getText().toString();        if ((keySize != 128) && (keySize != 256)) {            keySize = 256;        }        System.out.println("测试AES " + keySize + " 生成Key加密解密");        AESKeySpec = getAESKeySpec(keySize);        if (keySize == 128) {            System.out.println("获得加密的Key的字符串="+getAESKeyString());        }        else {            System.out.println(getAES256KeyString());        }        System.out.println("用户输入的原始明文="+str);        String cipherText = jiaMi(str);        System.out.println("加密后的密文="+cipherText);        String plainText = jieMi(cipherText);        System.out.println("解密后的明文="+plainText);    }    // 加密    public String jiaMi(String text) throws Exception {        Cipher cipher = Cipher.getInstance("AES");        cipher.init(Cipher.ENCRYPT_MODE, AESKeySpec);        //BASE64Encoder enc = new BASE64Encoder();        byte[] byteEnc = cipher.doFinal(text.getBytes("UTF-8"));        //return enc.encode(byteEnc);        return JiamiAndJiemiUtil.byte2hex(byteEnc);    }    //解密    public  String jieMi(String text) throws Exception {        Cipher cipher = Cipher.getInstance("AES");        cipher.init(Cipher.DECRYPT_MODE, AESKeySpec);        //BASE64Decoder dec = new BASE64Decoder();        //return new String(cipher.doFinal(dec.decodeBuffer(text)));        return new String(cipher.doFinal(JiamiAndJiemiUtil.hex2byte(text.getBytes("UTF-8"))));    }    // 取得AES的Key(秘钥)    public  SecretKeySpec getAESKeySpec(int keySize) throws IOException, NoSuchAlgorithmException {        SecretKey key = null;        SecretKeySpec spec = null;        if ((keySize != 128)  && (keySize != 192) && (keySize != 256)) {            keySize = 256;        }        if(keySize==256){            bytes2 = new byte[keySize/8];            String  fileName="256case.txt";            File f = new File(this.getFilesDir(),fileName);            Log.i("TAG","f的路径="+f.getPath());            Log.i("TAG","f="+f.getName());            // 如果存在Key文件，读取            if (f.exists()) {                new FileInputStream(f).read(bytes2);            }            // 如果不存在，重新生成Key，并写入Key文件            else {                KeyGenerator kgen = KeyGenerator.getInstance("AES");                kgen.init(keySize);                key = kgen.generateKey();                System.out.println("++++++++++++++++++++:key="+key);                bytes2 = key.getEncoded();                System.out.println("bytes="+bytes2);                new FileOutputStream(f).write(bytes2);            }            spec = new SecretKeySpec(bytes2, "AES");            return spec;        }else{            // AES 128 位            byte[] bytes = new byte[keySize / 8];            String  fileName="128case.txt";            File f = new File(this.getFilesDir(),fileName);            Log.i("TAG","f的路径="+f.getPath());            Log.i("TAG","f="+f.getName());            // 如果存在Key文件，读取            if (f.exists()) {                new FileInputStream(f).read(bytes);            }            // 如果不存在，重新生成Key，并写入Key文件            else {                KeyGenerator kgen = KeyGenerator.getInstance("AES");                kgen.init(keySize);                key = kgen.generateKey();                System.out.println("++++++++++++++++++++:key="+key);                bytes = key.getEncoded();                System.out.println("bytes="+bytes);                new FileOutputStream(f).write(bytes);            }            spec = new SecretKeySpec(bytes, "AES");            return spec;        }    }    // 取得AES  Key对应的字符串，傳遞此key 到Objective C    public static String getAESKeyString() {        // return new String(AESKeySpec.getEncoded());        return JiamiAndJiemiUtil.byte2hex(AESKeySpec.getEncoded());    }    // 取得AES Key对应的字符串，传递此key 到Objective C    public static String getAES256KeyString() {        // return new BASE64Encoder().encode(AESKeySpec.getEncoded());        return JiamiAndJiemiUtil.byte2hex(AESKeySpec.getEncoded());    }}
点击128加密和点击256加密后的结果如下：

I/System.out: 测试AES 128 生成Key加密解密I/TAG: f的路径=/data/user/0/james.myview/files/128case.txtI/TAG: f=128case.txtI/System.out: 获得128加密的Key的字符串=EE66D58C8FFC188648B8C32720FAB304I/System.out: 用户输入的原始明文=luluI/System.out: 加密后的密文=8D13E32DB1BEC38C8EE7D414F2F380E0I/System.out: 解密后的明文=luluI/System.out: 测试AES 256 生成Key加密解密I/TAG: f的路径=/data/user/0/james.myview/files/256case.txtI/TAG: f=256case.txtI/System.out: 获得256加密的Key的字符串=12109BCA993D53D3E2C3F2874469035604755EEEDB936C4F104AE4FBB049CADAI/System.out: 用户输入的原始明文=luluI/System.out: 加密后的密文=8F7C7B040D53068F6720DF68FB12670AI/System.out: 解密后的明文=lulu   

public class JiamiAndJiemiUtil {    //字节到十六进制的转换    public static String byte2hex(byte[] b){        String hs = "";        String stmp = "";        for (int n = 0; n < b.length; n ++){            stmp = Integer.toHexString(b[n] & 0xFF);            if (stmp.length() == 1)                hs += ("0" + stmp);            else                hs += stmp;        }        return hs.toUpperCase();    }    //十六进制到字节转换    public static byte[] hex2byte(byte[] b){        if ((b.length % 2) != 0)            throw new IllegalArgumentException("长度不是偶数!");        byte[] b2 = new byte[b.length / 2];        for (int n = 0; n < b.length; n += 2){            String item = new String(b, n, 2);            b2[n/2] = (byte)Integer.parseInt(item, 16);        }        return b2;    }}

另外一个网友的加密实现

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

import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

public class AESPlus {

    public static String encrypt(String strKey, String strIn) throws Exception {
        SecretKeySpec skeySpec = getKey(strKey);

            //获得一个私鈅加密类Cipher，ECB是加密方式，PKCS5Padding是填充方法
        Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
        IvParameterSpec iv = new IvParameterSpec("0102030405060708".getBytes());
        cipher.init(Cipher.ENCRYPT_MODE, skeySpec, iv);
        byte[] encrypted = cipher.doFinal(strIn.getBytes());

        return new BASE64Encoder().encode(encrypted);
    }

    public static String decrypt(String strKey, String strIn) throws Exception {
        SecretKeySpec skeySpec = getKey(strKey);
        Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
        IvParameterSpec iv = new IvParameterSpec("0102030405060708".getBytes());
        cipher.init(Cipher.DECRYPT_MODE, skeySpec, iv);
        byte[] encrypted1 = new BASE64Decoder().decodeBuffer(strIn);

        byte[] original = cipher.doFinal(encrypted1);
        String originalString = new String(original);
        return originalString;
    }

    private static SecretKeySpec getKey(String strKey) throws Exception {
        byte[] arrBTmp = strKey.getBytes();
        byte[] arrB = new byte[16]; // 创建一个空的16位字节数组（默认值为0）

        for (int i = 0; i < arrBTmp.length && i < arrB.length; i++) {
            arrB[i] = arrBTmp[i];
        }

        SecretKeySpec skeySpec = new SecretKeySpec(arrB, "AES");

        return skeySpec;
    }

    public static void main(String[] args) throws Exception {
        String Code = "中文ABc123";
        String key = "1q2w3e4r";
        String codE;

        codE = AESPlus.encrypt(key, Code);

        System.out.println("原文：" + Code);
        System.out.println("密钥：" + key);
        System.out.println("密文：" + codE);
        System.out.println("解密：" + AESPlus.decrypt(key, codE));
    }
}