package com.example.huangjialin.md5test;

import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class Utils {

    public static String md5(String content) {
        byte[] hash = null;
        try {
            hash = MessageDigest.getInstance("MD5").digest(content.getBytes("UTF-8"));
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }

        StringBuilder stringBuilder = new StringBuilder(hash.length * 2);
        for (byte b: hash) {
            if ((b & 0xFF) < 0x10){
                stringBuilder.append("0");

            }
            stringBuilder.append(Integer.toHexString(b & 0xFF));

        }
        return stringBuilder.toString();
    }

}

/**
* MD5加密
*/
button.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        String md5_123456abc = Utils.md5("123456abc");
        String md5_huangjialin = Utils.md5("huangjialin");
        Log.i("huangjialin","    md5_123456abc算出的MD5值是：    " + md5_123456abc);
        Log.i("huangjialin","    md5_huangjialin算出的MD5值是：   " + md5_huangjialin);
    }
});

/*
      初始化KeyPairGenerator類，并獲取到公鑰和私鑰
    */
    byte[] publicKeyByte;
    byte[] prvateKtyByte;

    public void getKey() {
        try {
            KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(“RSA”);//KeyPairGenerator類是java專門提供生成密鑰對(duì)的一個(gè)類。
            keyPairGenerator.initialize(1024); //設(shè)置密鑰對(duì)的大小
            KeyPair keyPair = keyPairGenerator.generateKeyPair();
            PrivateKey privateKey = keyPair.getPrivate();//獲取私鑰
            PublicKey publicKey = keyPair.getPublic();//獲取公鑰
            prvateKtyByte = privateKey.getEncoded();//私鑰對(duì)應(yīng)的字節(jié)數(shù)組
            publicKeyByte = publicKey.getEncoded(); //公鑰對(duì)應(yīng)的字節(jié)數(shù)組

        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
    }

/**
     * 加密
     */


    @RequiresApi(api = Build.VERSION_CODES.O)
    public byte[] encryption(String content) {
        byte[] result = null;
        try {
            Cipher cipher = Cipher.getInstance("RSA");
            X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(publicKeyByte);
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            PublicKey publicKey = keyFactory.generatePublic(x509EncodedKeySpec);
            cipher.init(Cipher.ENCRYPT_MODE, publicKey);
            result = cipher.doFinal(content.getBytes());
            Log.i("huangjialin", "---->  " + Base64.getEncoder().encodeToString(result));
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        } catch (NoSuchPaddingException e) {
            e.printStackTrace();
        } catch (InvalidKeySpecException e) {
            e.printStackTrace();
        } catch (InvalidKeyException e) {
            e.printStackTrace();
        } catch (BadPaddingException e) {
            e.printStackTrace();
        } catch (IllegalBlockSizeException e) {
            e.printStackTrace();
        }
        return result;
    }

/**
     * 解密
     */

    @RequiresApi(api = Build.VERSION_CODES.O)

    public void decryption() {

        Cipher cipher = null;
        try {
            cipher = Cipher.getInstance("RSA");
            //私鑰需要通過(guò)PKCS8EncodedKeySpec來(lái)讀取
            PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(prvateKtyByte);
            KeyFactory keyFactory = KeyFactory.getInstance("RSA");
            //生成私鑰
            PrivateKey privateKey = keyFactory.generatePrivate(keySpec);
            cipher.init(Cipher.DECRYPT_MODE, privateKey);
            //String content = "123456";
            byte[] input = encryption("123456");
            byte[] result = cipher.doFinal(input);
            Log.i("huangjialin", "--解密-->  " + new String(result));
            //Assert.assertTrue(content.equals(new String(result)));


        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        } catch (NoSuchPaddingException e) {
            e.printStackTrace();
        } catch (BadPaddingException e) {
            e.printStackTrace();
        } catch (IllegalBlockSizeException e) {
            e.printStackTrace();
        } catch (InvalidKeyException e) {
            e.printStackTrace();
        } catch (InvalidKeySpecException e) {
            e.printStackTrace();
        }


    }

private SecretKey generateKey(String seed) throws Exception {
        // 獲取秘鑰生成器
        KeyGenerator keyGenerator = KeyGenerator.getInstance("AES");
        // 通過(guò)種子初始化
        SecureRandom secureRandom = SecureRandom.getInstance("SHA1PRNG", "Crypto");

        secureRandom.setSeed(seed.getBytes("UTF-8"));
        keyGenerator.init(128, secureRandom);
        // 生成秘鑰并返回
        return keyGenerator.generateKey();
    }

package com.example.huangjialin.md5test;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Base64;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

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

public class MainActivity extends AppCompatActivity {
    private EditText edittext;
    private Button button, jiami, jiemi;
    private TextView textView;
    private SecretKey secretKey;
    private byte[] bytes;
    private String content = "huangjialin,我是要加密的數(shù)據(jù)";
    String password = "huangji黃家磷";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        edittext = findViewById(R.id.edittext);
        button = findViewById(R.id.button);
        textView = findViewById(R.id.textview);
        jiami = findViewById(R.id.jiami);
        jiemi = findViewById(R.id.jiemi);

        Log.i("huagjialin", "--加密的數(shù)據(jù)-- > " + content);

        /**
         * 獲取密鑰
         */
       /* button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                try {
                    secretKey = generateKey("huangjiain");
                } catch (Exception e) {
                    e.printStackTrace();
                }

            }
        });*/


        /**
         * 加密
         */

        jiami.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                try {
                    bytes = encrypt(content, password);
                    String str = new String(bytes);
                    Log.i("huagjialin", "--加密后的數(shù)據(jù)-- > " + Base64.decode(str,Base64.DEFAULT));
                } catch (Exception e) {
                    e.printStackTrace();
                }

            }
        });

        /**
         * 解密
         */

        jiemi.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                try {
                    byte[] by = decrypt(bytes, password);
                    String string = new String(by);
                    Log.i("huagjialin", "--解密后的數(shù)據(jù)-- > " + string);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });


    }

    /**
     * 另一種加密形式
     */
    private byte[] encrypt(String content, String password) throws Exception {
        // 創(chuàng)建AES秘鑰
        SecretKeySpec key = new SecretKeySpec(password.getBytes(), "AES/CBC/PKCS5PADDING");
        // 創(chuàng)建密碼器
        Cipher cipher = Cipher.getInstance("AES");
        // 初始化加密器
        cipher.init(Cipher.ENCRYPT_MODE, key);
        // 加密
        return cipher.doFinal(content.getBytes("UTF-8"));
    }


    /**
     * 解密
     */
    private byte[] decrypt(byte[] content, String password) throws Exception {
        // 創(chuàng)建AES秘鑰
        SecretKeySpec key = new SecretKeySpec(password.getBytes(), "AES/CBC/PKCS5PADDING");
        // 創(chuàng)建密碼器
        Cipher cipher = Cipher.getInstance("AES");
        // 初始化解密器
        cipher.init(Cipher.DECRYPT_MODE, key);
        // 解密
        return cipher.doFinal(content);
    }

}