RSA加密算法解析+数字签名验证

RSA加密算法

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• 此Demo实现以下这几个功能

布局文件就不往出列了

1 . 生成公钥私钥
这是一个耗时操作,是通过随意选择两个大的质数经过一系列的复杂运算获得的,想了解算法自行百度,这里只说一下它如何使用!
case 的时候封装为一个方法

private void generateRsa() {        new Thread(new Runnable() {            @Override            public void run() {                //1.获取keyPareGenerator                try {                    KeyPairGenerator keyPairGenerator=KeyPairGenerator.getInstance("RSA");                    //2.进行初始化,长度                    keyPairGenerator.initialize(1024);                    //3.获取密码                    KeyPair keyPair = keyPairGenerator.generateKeyPair();                    //4.获取私钥                    privateKey = keyPair.getPrivate();                    publicKey = keyPair.getPublic();                    //展示数据:                    final byte[] privateKeyEncoded = privateKey.getEncoded();                    final byte[] publicKeyEncoded = publicKey.getEncoded();                    //将密钥保存,如果不需要可以省略                    SharedPreferences sp = MainActivity.this.getSharedPreferences("config", MODE_PRIVATE);                    SharedPreferences.Editor editor = sp.edit();                    editor.putString("privateKey",Base64.encodeToString(privateKeyEncoded,Base64.DEFAULT));                    editor.putString("publicKey",Base64.encodeToString(publicKeyEncoded,Base64.DEFAULT));                    editor.commit();//将获取到的内容显示到界面上                    runOnUiThread(new Runnable() {                        @Override                        public void run() {                            StringBuilder builder = new StringBuilder();                            builder.append("私钥是:"+'\n');                            builder.append(Base64.encodeToString(privateKeyEncoded,Base64.DEFAULT)+'\n');                            builder.append("公钥是:"+'\n');                            builder.append(Base64.encodeToString(publicKeyEncoded,Base64.DEFAULT)+'\n');                            mResult.setText(builder.toString());                        }                    });                } catch (NoSuchAlgorithmException e) {                    e.printStackTrace();                }            }        }).start();    }

2 . RSA加密(私钥加密)

直接从缓存中获取,SharedPreferences

//全局的常量声明private String data = "Google Home 或 Amazon Echo 值得买吗?";case R.id.encrypt:                //                String privateKey = sp.getString("privateKey", null);                byte[] decode = Base64.decode(privateKey, Base64.DEFAULT);                try {                    KeyFactory keyFactory = KeyFactory.getInstance("RSA");                    //私钥字节数组转换成私钥                    PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(decode);                    PrivateKey privateKey1 = keyFactory.generatePrivate(keySpec);                    String encrypt = encrypt(data, privateKey1, 0);                    mResult.setText(encrypt);                } catch (NoSuchAlgorithmException e) {                    e.printStackTrace();                } catch (InvalidKeySpecException e) {                    e.printStackTrace();                }                break;

3 . RSA解密(公钥解密)

case R.id.decode:                String publicKey = sp.getString("publicKey", null);                byte[] decode1 = Base64.decode(publicKey, Base64.DEFAULT);                try {                    KeyFactory keyFactory = KeyFactory.getInstance("RSA");                    X509EncodedKeySpec keySpec = new X509EncodedKeySpec(decode1);                    PublicKey publicKey1 = keyFactory.generatePublic(keySpec);                    String data = mResult.getText().toString().trim();                    String s = encrypt(data, publicKey1, 1);                    mResult.setText(s);                } catch (NoSuchAlgorithmException e) {                    e.printStackTrace();                } catch (InvalidKeySpecException e) {                    e.printStackTrace();                }                break;

• encrypt(data, publicKey1, 1);
  该方法判断加密还是解密.

private String encrypt(String data, Key Key, int type) {        try {            Cipher cipher = Cipher.getInstance("RSA");            //设置密码            switch (type) {                case 0:                    cipher.init(Cipher.ENCRYPT_MODE,Key);                    break;                case 1:                    cipher.init(Cipher.DECRYPT_MODE,Key);                    break;            }            //区分加密解密:            switch (type) {                case 0:                    byte[] bytes = cipher.doFinal(data.getBytes());                    byte[] encode = Base64.encode(bytes, Base64.DEFAULT);                    String result = new String(encode);                     return result;                case 1:                    byte[] decode = Base64.decode(data, Base64.DEFAULT);                    byte[] doFinal = cipher.doFinal(decode);                    String dResult = new String(doFinal);                    return dResult;            }        }        //这里注意抛异常         return data;

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4 . 数字签名

• 数字签名使用私钥进行加密 MD5withRSA
• 核心的方法:
  1.Signature.getInstance(“MD5withRSA”);初始化操作
  2.signature.initSign(privateKey); 使用私钥进行签名
  3.signature.update(data.getBytes()); 签名的数据
  4.byte[] sign = signature.sign();生成签名
  5.使用Base64编码否则传输的为乱码

case R.id.md5Rsa://数字签名，使用私钥进行                try {                    Signature signature = Signature.getInstance("MD5withRSA");                    signature.initSign(privateKey);                    signature.update(this.data.getBytes());                    byte[] sign = signature.sign();//签名的数据                    //将源文件和签名的数据一块发送给合作伙伴                    mSignResult = Base64.encodeToString(sign, Base64.DEFAULT);                    Log.d("flag", "----------------->rsa: 要传送给合作伙伴的数据： " +this.data+", 数字签名： "+mSignResult);                } catch (NoSuchAlgorithmException e) {                    e.printStackTrace();                } catch (InvalidKeyException e) {                    e.printStackTrace();                } catch (SignatureException e) {                    e.printStackTrace();                }                break;

5 . 验证数字签名
- 核心方法
boolean verify = signature.verify();判断验证的结果

case R.id.md5vertify:                try {                    Signature signature = Signature.getInstance("MD5withRSA");                    //数字验证，使用公钥                    signature.initVerify(mKeyPairPublic);                    //update,传递过来的源文件                    signature.update(this.data.getBytes());                    //对签名进行验证 mSignResult                    boolean verify = signature.verify(Base64.decode(mSignResult, Base64.DEFAULT));                    Log.d("flag", "---------->rsa: 验证结果： " +verify);                } catch (NoSuchAlgorithmException e) {                    e.printStackTrace();                } catch (InvalidKeyException e) {                    e.printStackTrace();                } catch (SignatureException e) {                    e.printStackTrace();                }                break;

• 最后结束程序将数据置空,减少内存的占用

@Override    protected void onDestroy() {        super.onDestroy();        result = null;        data = null;    }

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判断公钥-私钥是否匹配

//取出私钥        //从sp中获取私钥        String privateKey = sp.getString("privateKey", null);        byte[] decode = Base64.decode(privateKey, Base64.DEFAULT);        //私钥字节数组转换成私钥        try {            KeyFactory keyFactory = KeyFactory.getInstance("RSA");            //PKCS8EncodedKeySpec ---->对应RSA 私钥            KeySpec keySpec = new PKCS8EncodedKeySpec(decode);            mKeyPairPrivate = keyFactory.generatePrivate(keySpec);        } catch (NoSuchAlgorithmException e) {            e.printStackTrace();        } catch (InvalidKeySpecException e) {            e.printStackTrace();        }        String publicKey =this.publicKey;        byte[] decode1 = Base64.decode(publicKey, Base64.DEFAULT);        try {            KeyFactory keyFactory = KeyFactory.getInstance("RSA");            //X509EncodedKeySpec ----->RSA 公钥            KeySpec keySpec = new X509EncodedKeySpec(decode1);            mKeyPairPublic = keyFactory.generatePublic(keySpec);        } catch (NoSuchAlgorithmException e) {            e.printStackTrace();        } catch (InvalidKeySpecException e) {            e.printStackTrace();        }