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RSA初步完成
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‎README.md‎

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@@ -333,4 +333,194 @@ public class AESDemo {
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}
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}
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```
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## 非对称加密
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### 1. 对称加密的弊端
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- 秘钥分发困难
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- 可以通过非对称加密完成秘钥的分发
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> https
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>
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> Alice 和 Bob通信, Alice给bob发送数据, 使用对称加密的方式
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>
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> 1. 生成一个非对称的秘钥对, bob生成
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> 2. bob将公钥发送给alice
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> 3. alice生成一个用于对称加密的秘钥
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> 4. alice使用bob的公钥就对称加密的秘钥进行加密, 并且发送给bob
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> 5. bob使用私钥就数据解密, 得到对称加密的秘钥
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> 6. 通信的双方使用写好的秘钥进行对称加密数据加密
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### 2. 非对称加密的秘钥
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- 不存在秘钥分发困难的问题
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#### 2.1 场景分析
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数据对谁更重要, 谁就拿私钥
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- 直观上看: 私钥比公钥长
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- 使用第三方工具生成密钥对: 公钥文件xxx.pub xxx
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> 1. 通信流程, 信息加密 （A写数据, 发送给B, 信息只允许B读）
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>
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> A: 公钥
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>
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> B: 私钥
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>
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> 2. 登录认证 （客户端要登录, 连接服务器, 向服务器请求个人数据）
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>
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> 客户端: 私钥
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>
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> 服务器: 公钥
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>
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> 3. 数字签名（表明信息没有受到伪造，确实是信息拥有者发出来的，附在信息原文的后面）
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>
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> - 发送信息的人: 私钥
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> - 收到信息的人: 公钥
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>
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> 4. 网银U盾
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>
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> - 个人: 私钥
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> - 银行拿公钥
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### 3. 使用RSA非对称加密通信流程
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> 要求: Alice 给 bob发送数据, 保证数据信息只有bob能看到
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### 4. 生成RSA的秘钥对
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#### 4.1 一些概念
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1. x509证书规范、pem、base64
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- pem编码规范 - 数据加密
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- base64 - 对数据编码, 可逆
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- 不管原始数据是什么, 将原始数据使用64个字符来替代
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- a-z A-Z 0-9 + /
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2. ASN.1抽象语法标记
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3. PKCS1标准
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### 5. 常见算法
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> RSA
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> ECC(java需要借助第三方库实现加密解密,我将在另外一个项目中用go实现)
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###6 RSA示例代码如下
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- 注意:经测试在后端使用Cipher.getInstance(“RSA”)加密,在移动端获取解密的Cipher类时要使用Cipher.getInstance(“RSA/ECB/PKCS1Padding”)
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- 移动端核心代码
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```$java
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//后端用私钥加密过的数据
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String eText = "ETLPedgx7vR9E9JGNIj4pLhvurcOM26oo4RgJhmeF5RvDXVdl3qQ+5H6hmUx3dV2K8jPxi5aKSVs1xnjuMgSfK32fjrqzYBULFaBCmnN1HbpcwYFNMA3enWiVwT3TAWFKA9ReJ2DWh0lkCzaHruOmcWCY3f2tjuEE9X9L0DN7m5R9iy2qgEEDPgfzImYYl8wltYdudryz2fQ7UNGdIUPc75EMqdvHEUrxIi5A7cM0BDGQI2aXD+39ijQCOVBtai/9ohF7YXtGmbsocPBKarhe8qpVIcvXza6fBbOWxBC6Z68uRGcljTVkhvNjWrEmRuu5pc3C41bx4OK9FD8kPgITg==";
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//后端给的公钥
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String pkey = "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAmpz9g5IX3ElRtXFo2+9nwD4+amqhEH4Rz1FI2cXeSiQeLPfdCoSsflLovdJ21NxvcKGw9IvmjWkLESCVU/pxDeP2UkVXFAjC2KhZvoQO4v0x4Yn3/55bAAQ9O3qoGatjPlDbzr1CEAi+ZA7NY1Oz2TtOSq8Odc7wc3Sq6U1gZBf87w5jq0GwQwgLrQjaVf5oTgKmavyf6g8Uq8U0QnktXCJpJUsSSZdeWTwAhtKk+MDkd5VRHIynLklOgeAhjG7xzEAad/Q32qLGcCwY+ySiZWLZ5q5uZAys4rj98LiwV6zLyk8CYYclUDUtBPLLXDRN8DUEe4uKAucFC4IlkrXQ0wIDAQAB";
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//获取公钥对象
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KeyFactory keyFactory = KeyFactory.getInstance(algorithm);
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X509EncodedKeySpec spec = new X509EncodedKeySpec(Base64.decode(pkey, Base64.DEFAULT));
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PublicKey publicKey = keyFactory.generatePublic(spec);
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//指定解密algorithm = "RSA/ECB/PKCS1Padding"; Cipher cipher = Cipher.getInstance(algorithm);
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algorithm = "RSA/ECB/PKCS1Padding";
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String decrypt = RSADemo.RSADecrypt(algorithm, publicKey, eText, 256);
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System.out.println("decript###" + decrypt + "###");
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```
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- 后端代码
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```java
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public class RSADemo {
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private static int MAX_ENCRIPT_SIZE = 200;
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public static void main(String[] args) throws Exception {
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String algorithm = "RSA";
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String input = "frank";
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// generateKeys(algorithm, "test.pri", "test.pub");
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PrivateKey privateKey = getPrivateKey("test.pri", algorithm);
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PublicKey publicKey = getPublicKey("test.pub", algorithm);
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String encryptData = RSAEncrypt(algorithm, privateKey, input, MAX_ENCRIPT_SIZE);
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System.out.println("encryptData=" + encryptData);
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String decryptData = RSADecrypt(algorithm, publicKey, encryptData, 256);
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System.out.println("decryptData=" + decryptData);
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}
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public static PrivateKey getPrivateKey(String priPath, String algorithm) throws Exception {
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String privateKeyString = FileUtils.readFileToString(new File(priPath), Charset.defaultCharset());
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KeyFactory keyFactory = KeyFactory.getInstance(algorithm);
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PKCS8EncodedKeySpec spec = new PKCS8EncodedKeySpec(Base64.decode(privateKeyString));
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return keyFactory.generatePrivate(spec);
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}
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public static PublicKey getPublicKey(String pubPath, String algorithm) throws Exception {
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String publicKeyString = FileUtils.readFileToString(new File(pubPath), Charset.defaultCharset());
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KeyFactory keyFactory = KeyFactory.getInstance(algorithm);
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X509EncodedKeySpec spec = new X509EncodedKeySpec(Base64.decode(publicKeyString));
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return keyFactory.generatePublic(spec);
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}
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public static void generateKeys(String algorithm, String priPath, String pubPath) throws Exception {
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// 获取密钥对生成器
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KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(algorithm);
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// 获取密钥对
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KeyPair keyPair = keyPairGenerator.generateKeyPair();
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// 获取公私钥
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PrivateKey privateKey = keyPair.getPrivate();
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PublicKey publicKey = keyPair.getPublic();
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// 获取公私钥的字节数组
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byte[] privateKeyEncoded = privateKey.getEncoded();
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byte[] publicKeyEncoded = publicKey.getEncoded();
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// 对公私钥进行Base64的编码
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String privateKeyString = Base64.encode(privateKeyEncoded);
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String publicKeyString = Base64.encode(publicKeyEncoded);
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FileUtils.writeStringToFile(new File(priPath), privateKeyString, Charset.defaultCharset());
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FileUtils.writeStringToFile(new File(pubPath), publicKeyString, Charset.defaultCharset());
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}
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public static String RSAEncrypt(String algorithm, Key key, String input, int maxEncryptSize) throws Exception {
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Cipher cipher = Cipher.getInstance(algorithm);
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cipher.init(Cipher.ENCRYPT_MODE, key);
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byte[] data = input.getBytes();
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int total = data.length;
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int offset = 0;
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ByteArrayOutputStream baos = new ByteArrayOutputStream();
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byte[] bytes;
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while (total - offset > 0) {
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if (total - offset >= maxEncryptSize) {
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bytes = cipher.doFinal(data, offset, maxEncryptSize);
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offset += maxEncryptSize;
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} else {
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bytes = cipher.doFinal(data, offset, total - offset);
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offset = total;
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}
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baos.write(bytes);
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}
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return Base64.encode(baos.toByteArray());
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}
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public static String RSADecrypt(String algorithm, Key key, String input, int maxEncryptSize) throws Exception {
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Cipher cipher = Cipher.getInstance(algorithm);
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cipher.init(Cipher.DECRYPT_MODE, key);
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byte[] data = Base64.decode(input);
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int total = data.length;
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int offset = 0;
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ByteArrayOutputStream baos = new ByteArrayOutputStream();
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byte[] bytes;
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while (total - offset > 0) {
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if (total - offset >= maxEncryptSize) {
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bytes = cipher.doFinal(data, offset, maxEncryptSize);
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offset += maxEncryptSize;
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} else {
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bytes = cipher.doFinal(data, offset, total - offset);
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offset = total;
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}
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baos.write(bytes);
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}
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return baos.toString();
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}
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}
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```

‎androidcode/MainActivity.java‎

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package bupin.com.tmpdemo;
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import android.support.v7.app.AppCompatActivity;
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import android.os.Bundle;
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import android.util.Base64;
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import android.util.Log;
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import android.view.View;
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import android.widget.Button;
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import android.widget.TextView;
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import android.widget.Toast;
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import org.apache.commons.io.FileUtils;
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import java.io.File;
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import java.nio.charset.Charset;
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import java.security.KeyFactory;
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import java.security.NoSuchAlgorithmException;
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import java.security.PrivateKey;
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import java.security.PublicKey;
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import java.security.spec.InvalidKeySpecException;
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import java.security.spec.X509EncodedKeySpec;
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public class MainActivity extends AppCompatActivity implements View.OnClickListener {
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private static final String TAG = "MainActivity";
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private TextView mTv;
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private Button mBt1;
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private Button mBt2;
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private Button mBt3;
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@Override
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protected void onCreate(Bundle savedInstanceState) {
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super.onCreate(savedInstanceState);
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setContentView(R.layout.activity_main);
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mTv = findViewById(R.id.tv);
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mBt1 = findViewById(R.id.bt1);
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mBt2 = findViewById(R.id.bt2);
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mBt3 = findViewById(R.id.bt3);
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mBt1.setOnClickListener(this);
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mBt2.setOnClickListener(this);
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mBt3.setOnClickListener(this);
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}
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@Override
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public void onClick(View v) {
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String algorithm = "RSA";
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String input = "frank";
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String priPath = this.getFilesDir().getAbsolutePath() + File.separator + "a.pri";
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String pubPath = this.getFilesDir().getAbsolutePath() + File.separator + "a.pub";
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switch (v.getId()) {
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case R.id.bt1:
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Log.d(TAG, priPath);
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Log.d(TAG, pubPath);
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try {
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RSADemo.generateKeys(algorithm, priPath, pubPath);
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} catch (Exception e) {
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e.printStackTrace();
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Toast.makeText(this, "生成key出异常了", Toast.LENGTH_SHORT).show();
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}
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break;
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case R.id.bt2:
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try {
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PrivateKey privateKey = RSADemo.getPrivateKey(priPath, algorithm);
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PublicKey publicKey = RSADemo.getPublicKey(pubPath, algorithm);
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String encryptData = RSADemo.RSAEncrypt(algorithm, privateKey, input, 245);
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Log.d(TAG, "encryptData=" + encryptData);
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String decryptData = RSADemo.RSADecrypt(algorithm, publicKey, encryptData, 256);
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Log.d(TAG, "decryptData=" + decryptData);
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} catch (Exception e) {
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e.printStackTrace();
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Toast.makeText(this, "加解密出异常了", Toast.LENGTH_SHORT).show();
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}
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break;
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case R.id.bt3:
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try {
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// String eText = "XURae8f0eiLfhkrFVJ+2Kn1aZ4tIDs4Mo9vVd9tLo2WkpD6e/m2UhUB7KHnMhz0Q3enwpr+hTMEntDFY0ydu0Tk0cHtQeA1PjinhF4N/Z3D73167LDrULVmxvcZYrTA6rY7yj9noK8nqDGa2qNl/IF27+KTjBXxB6Wf1OUYR8Uvk04Yu9X4MU93T/KGRu3+N/ewX8mT6M7b8CFviGG5ADpwglTK6Tl2bt+lylbMDc1wtfnKxGcLCeIxKH9gazytoFP7scrc63lrD5gK3+lhb0nRPSk4v7fCd0+5ILwquQc5IkGuphjneyRSyNPKfpKaZcLKJw9B6YXtJGOQC1V3fFw==";
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//后端用私钥加密过的数据
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String eText = "ETLPedgx7vR9E9JGNIj4pLhvurcOM26oo4RgJhmeF5RvDXVdl3qQ+5H6hmUx3dV2K8jPxi5aKSVs1xnjuMgSfK32fjrqzYBULFaBCmnN1HbpcwYFNMA3enWiVwT3TAWFKA9ReJ2DWh0lkCzaHruOmcWCY3f2tjuEE9X9L0DN7m5R9iy2qgEEDPgfzImYYl8wltYdudryz2fQ7UNGdIUPc75EMqdvHEUrxIi5A7cM0BDGQI2aXD+39ijQCOVBtai/9ohF7YXtGmbsocPBKarhe8qpVIcvXza6fBbOWxBC6Z68uRGcljTVkhvNjWrEmRuu5pc3C41bx4OK9FD8kPgITg==";
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//后端给的公钥
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String pkey = "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAmpz9g5IX3ElRtXFo2+9nwD4+amqhEH4Rz1FI2cXeSiQeLPfdCoSsflLovdJ21NxvcKGw9IvmjWkLESCVU/pxDeP2UkVXFAjC2KhZvoQO4v0x4Yn3/55bAAQ9O3qoGatjPlDbzr1CEAi+ZA7NY1Oz2TtOSq8Odc7wc3Sq6U1gZBf87w5jq0GwQwgLrQjaVf5oTgKmavyf6g8Uq8U0QnktXCJpJUsSSZdeWTwAhtKk+MDkd5VRHIynLklOgeAhjG7xzEAad/Q32qLGcCwY+ySiZWLZ5q5uZAys4rj98LiwV6zLyk8CYYclUDUtBPLLXDRN8DUEe4uKAucFC4IlkrXQ0wIDAQAB";
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//获取公钥对象
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KeyFactory keyFactory = KeyFactory.getInstance(algorithm);
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X509EncodedKeySpec spec = new X509EncodedKeySpec(Base64.decode(pkey, Base64.DEFAULT));
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PublicKey publicKey = keyFactory.generatePublic(spec);
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//指定解密algorithm = "RSA/ECB/PKCS1Padding"; Cipher cipher = Cipher.getInstance(algorithm);
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algorithm = "RSA/ECB/PKCS1Padding";
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String decrypt = RSADemo.RSADecrypt(algorithm, publicKey, eText, 256);
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System.out.println("decript###" + decrypt + "###");
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} catch (Exception e) {
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e.printStackTrace();
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Toast.makeText(this, "夸平台解密错误", Toast.LENGTH_SHORT).show();
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}
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break;
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}
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}
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}

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