RSA加密,解密 与数字签名

package com.e

                             RSA加密算法的简单使用原理

xample.subang.advancesix;import android.content.SharedPreferences;import android.support.v7.app.AppCompatActivity;import android.os.Bundle;import android.util.Base64;import android.util.Log;import android.view.View;import android.widget.TextView;import java.security.InvalidKeyException;import java.security.Key;import java.security.KeyFactory;import java.security.KeyPair;import java.security.KeyPairGenerator;import java.security.NoSuchAlgorithmException;import java.security.PrivateKey;import java.security.PublicKey;import java.security.Signature;import java.security.SignatureException;import java.security.spec.InvalidKeySpecException;import java.security.spec.KeySpec;import java.security.spec.PKCS8EncodedKeySpec;import java.security.spec.X509EncodedKeySpec;import javax.crypto.BadPaddingException;import javax.crypto.Cipher;import javax.crypto.IllegalBlockSizeException;import javax.crypto.NoSuchPaddingException;public class MainActivity extends AppCompatActivity {    private TextView text;    private String data = "怒发冲冠,凭栏处,潇潇雨歇";    private PrivateKey aPrivate;    private PublicKey aPublic;    private SharedPreferences sp;    private PrivateKey privateKey1;    private PublicKey publicKey1;    private String s;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        text = (TextView) findViewById(R.id.text);        sp = getSharedPreferences("config", MODE_PRIVATE);        //从sp中获取私钥        String privateKey = sp.getString("privateKey", null);        byte[] decode = Base64.decode(privateKey, Base64.DEFAULT);        KeyFactory keyFactory = null;        try {            keyFactory = KeyFactory.getInstance("RSA");        } catch (NoSuchAlgorithmException e) {            e.printStackTrace();        }        KeySpec keySpec = new PKCS8EncodedKeySpec(decode);        try {            privateKey1 = keyFactory.generatePrivate(keySpec);        } catch (InvalidKeySpecException e) {            e.printStackTrace();        }        //从sp中获取公钥        String publicKey = sp.getString("publicKey", null);        byte[] decode1 = Base64.decode(publicKey, Base64.DEFAULT);        KeyFactory keyFactory2 = null;        try {            keyFactory2 = KeyFactory.getInstance("RSA");        } catch (NoSuchAlgorithmException e) {            e.printStackTrace();        }        KeySpec keySpec2 = new X509EncodedKeySpec(decode1);        try {            publicKey1 = keyFactory2.generatePublic(keySpec2);        } catch (InvalidKeySpecException e) {            e.printStackTrace();        }    }    public void start(View view) throws BadPaddingException, InvalidKeyException, IllegalBlockSizeException, NoSuchAlgorithmException, InvalidKeySpecException, SignatureException {        switch (view.getId()) {            case R.id.btn1:                generateRsa();                break;            case R.id.btn2:                String cyrpt = cyrpt(data, privateKey1, 0);                text.setText(cyrpt);                break;            case R.id.btn3:                String trim = text.getText().toString().trim();                String cyrpt1 = cyrpt(trim, publicKey1, 1);                text.setText(cyrpt1);                break;            case  R.id.md5Rsa://数字签名,使用私钥进行                Signature signature=Signature.getInstance("MD5withRSA");                signature.initSign(privateKey1);                signature.update(this.data.getBytes());                byte[] sign = signature.sign();//签名的数据                //将原文件和签名之后的数据一块发送给合作伙伴                s = Base64.encodeToString(sign, Base64.DEFAULT);                text.setText(s);                break;            case  R.id.md5vertify://数字验证,使用公钥                Signature signature1=Signature.getInstance("MD5withRSA");                signature1.initVerify(publicKey1);                //update 将原文件上传给signature                signature1.update(this.data.getBytes());                //对签名进行验证 s                boolean verify = signature1.verify(Base64.decode(s, Base64.DEFAULT));                Log.e("flag", "--------------------->start: 验证的结果"+verify);                break;            default:                break;        }    }    private String cyrpt(String data, Key key, int type) throws InvalidKeyException, BadPaddingException, IllegalBlockSizeException {        try {            //1.加密引擎            Cipher cipher = Cipher.getInstance("RSA");            //2.设置密码            switch (type) {                case 0://加密                    cipher.init(Cipher.ENCRYPT_MODE, key);                    break;                case 1://解密                    cipher.init(Cipher.DECRYPT_MODE, key);                    break;                                default:                    break;            }            //3.区分加密 解密            switch (type) {                case 0://加密                    byte[] bytes = cipher.doFinal(data.getBytes());                    byte[] encode = Base64.encode(bytes, Base64.DEFAULT);                    String result = new String(encode);                    return result;                case 1://解密                    byte[] decode = Base64.decode(data, Base64.DEFAULT);                    byte[] bytes1 = cipher.doFinal(decode);                    String result1 = new String(bytes1);                    return result1;                default:                    break;            }        } catch (NoSuchAlgorithmException e) {            e.printStackTrace();        } catch (NoSuchPaddingException e) {            e.printStackTrace();        }        return data;    }    private void generateRsa() {        new Thread(new Runnable() {            @Override            public void run() {                //1.获取KeyPareGenerator                try {                    KeyPairGenerator keypairGenerator = KeyPairGenerator.getInstance("RSA");                    //2.初始化                    keypairGenerator.initialize(1024);                    //3.获取密码                    KeyPair keyPair = keypairGenerator.generateKeyPair();                    //4.获取公钥 ,私钥                    aPrivate = keyPair.getPrivate();                    aPublic = keyPair.getPublic();                    //5.展示数据                    final byte[] aByte = aPrivate.getEncoded();                    final byte[] pByte = aPublic.getEncoded();                    //将公钥 , 私钥 进行保存 保存到sp中                    SharedPreferences sp = MainActivity.this.getSharedPreferences("config", MODE_PRIVATE);                    SharedPreferences.Editor editor = sp.edit();                    editor.putString("privateKey", Base64.encodeToString(aByte, Base64.DEFAULT));                    editor.putString("publicKey", Base64.encodeToString(pByte, Base64.DEFAULT));                    editor.commit();                    runOnUiThread(new Runnable() {                        @Override                        public void run() {                            StringBuilder builder = new StringBuilder();                            builder.append("私钥是:" + "\n");                            builder.append(Base64.encodeToString(aByte, Base64.DEFAULT) + "\n");                            builder.append("公钥是:" + "\n");                            builder.append(Base64.encodeToString(pByte, Base64.DEFAULT));                            text.setText(builder.toString());                        }                    });                } catch (NoSuchAlgorithmException e) {                    e.printStackTrace();                }            }        }).start();    }    @Override    protected void onDestroy() {        super.onDestroy();        text = null;        data = null;    }}