因业务需要，需要给android应用安装证书，通过读取证书文件内容实现某些功能的控制；

流程：后台通过publicKey对指定内容的文件进行加密，生成文件共客户下载，客户下载后选择该证书文件读取到应用中；

后台加密代码：

package com.zl.unit.printunit;import org.springframework.util.Base64Utils;import java.io.ByteArrayOutputStream;
import java.security.Key;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;
import javax.crypto.Cipher;/** */
/*** <p>* RSA公钥/私钥/签名工具包* </p>* <p>* 字符串格式的密钥在未在特殊说明情况下都为BASE64编码格式<br/>* 由于非对称加密速度极其缓慢，一般文件不使用它来加密而是使用对称加密，<br/>* 非对称加密算法可以用来对对称加密的密钥加密，这样保证密钥的安全也就保证了数据的安全* </p>** @author zhagnlei* @date 2019-4-29* @version 1.0*/
public class RSAUtils {/** *//*** 加密算法RSA*/public static final String KEY_ALGORITHM = "RSA";/** *//*** 签名算法*/public static final String SIGNATURE_ALGORITHM = "MD5withRSA";/** *//*** 获取公钥的key*/private static final String PUBLIC_KEY = "RSAPublicKey";/** *//*** 获取私钥的key*/private static final String PRIVATE_KEY = "RSAPrivateKey";/** *//*** RSA最大加密明文大小*/private static final int MAX_ENCRYPT_BLOCK = 117;/** *//*** RSA最大解密密文大小*/private static final int MAX_DECRYPT_BLOCK = 128;private static final String PRIVATE_KEY_CODE = "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";private static final String PUBLIC_KEY_CODE = "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDiMPz4qbXd9we8q4gnaGg3NaeH1Vbj9JA7odkBDDKCX5RoJotSPLX5n/6dWh3imUVmc6HNMo8oBOhki/W7+1KMyOUqI+h/uQDa35EvgrUSPwyc0QZszCyakk0uXtGqLdQz/IgrsywXfIzNL5sQ2679xinch4efgaikApmXYhSDywIDAQAB";/** *//*** <p>* 生成密钥对(公钥和私钥)* </p>** @return* @throws Exception*/public static Map<String, Object> genKeyPair() throws Exception {KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(KEY_ALGORITHM);keyPairGen.initialize(1024);KeyPair keyPair = keyPairGen.generateKeyPair();RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();Map<String, Object> keyMap = new HashMap<String, Object>(2);keyMap.put(PUBLIC_KEY, publicKey);keyMap.put(PRIVATE_KEY, privateKey);return keyMap;}/** *//*** <p>* 用私钥对信息生成数字签名* </p>** @param data       已加密数据* @param privateKey 私钥(BASE64编码)* @return* @throws Exception*/public static String sign(byte[] data, String privateKey) throws Exception {byte[] keyBytes = Base64Utils.decodeFromString(privateKey);PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);PrivateKey privateK = keyFactory.generatePrivate(pkcs8KeySpec);Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);signature.initSign(privateK);signature.update(data);return Base64Utils.encodeToString(signature.sign());}/** *//*** <p>* 校验数字签名* </p>** @param data      已加密数据* @param publicKey 公钥(BASE64编码)* @param sign      数字签名* @return* @throws Exception*/public static boolean verify(byte[] data, String publicKey, String sign) throws Exception {byte[] keyBytes = Base64Utils.decodeFromString(publicKey);X509EncodedKeySpec keySpec = new X509EncodedKeySpec(keyBytes);KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);PublicKey publicK = keyFactory.generatePublic(keySpec);Signature signature = Signature.getInstance(SIGNATURE_ALGORITHM);signature.initVerify(publicK);signature.update(data);return signature.verify(Base64Utils.decodeFromString(sign));}/** *//*** <P>* 私钥解密* </p>** @param encryptedData 已加密数据* @param privateKey    私钥(BASE64编码)* @return* @throws Exception*/public static byte[] decryptByPrivateKey(byte[] encryptedData, String privateKey) throws Exception {byte[] keyBytes = Base64Utils.decodeFromString(privateKey);PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());cipher.init(Cipher.DECRYPT_MODE, privateK);int inputLen = encryptedData.length;ByteArrayOutputStream out = new ByteArrayOutputStream();int offSet = 0;byte[] cache;int i = 0;// 对数据分段解密while (inputLen - offSet > 0) {if (inputLen - offSet > MAX_DECRYPT_BLOCK) {cache = cipher.doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK);} else {cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet);}out.write(cache, 0, cache.length);i++;offSet = i * MAX_DECRYPT_BLOCK;}byte[] decryptedData = out.toByteArray();out.close();return decryptedData;}/** *//*** <p>* 公钥解密* </p>** @param encryptedData 已加密数据* @param publicKey     公钥(BASE64编码)* @return* @throws Exception*/public static byte[] decryptByPublicKey(byte[] encryptedData, String publicKey) throws Exception {byte[] keyBytes = Base64Utils.decodeFromString(publicKey);X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);Key publicK = keyFactory.generatePublic(x509KeySpec);Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());cipher.init(Cipher.DECRYPT_MODE, publicK);int inputLen = encryptedData.length;ByteArrayOutputStream out = new ByteArrayOutputStream();int offSet = 0;byte[] cache;int i = 0;// 对数据分段解密while (inputLen - offSet > 0) {if (inputLen - offSet > MAX_DECRYPT_BLOCK) {cache = cipher.doFinal(encryptedData, offSet, MAX_DECRYPT_BLOCK);} else {cache = cipher.doFinal(encryptedData, offSet, inputLen - offSet);}out.write(cache, 0, cache.length);i++;offSet = i * MAX_DECRYPT_BLOCK;}byte[] decryptedData = out.toByteArray();out.close();return decryptedData;}/** *//*** <p>* 公钥加密* </p>** @param data      源数据* @param publicKey 公钥(BASE64编码)* @return* @throws Exception*/public static byte[] encryptByPublicKey(byte[] data, String publicKey) throws Exception {byte[] keyBytes = Base64Utils.decodeFromString(publicKey);X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(keyBytes);KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);Key publicK = keyFactory.generatePublic(x509KeySpec);// 对数据加密Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());cipher.init(Cipher.ENCRYPT_MODE, publicK);int inputLen = data.length;ByteArrayOutputStream out = new ByteArrayOutputStream();int offSet = 0;byte[] cache;int i = 0;// 对数据分段加密while (inputLen - offSet > 0) {if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);} else {cache = cipher.doFinal(data, offSet, inputLen - offSet);}out.write(cache, 0, cache.length);i++;offSet = i * MAX_ENCRYPT_BLOCK;}byte[] encryptedData = out.toByteArray();out.close();return encryptedData;}/** *//*** <p>* 私钥加密* </p>** @param data       源数据* @param privateKey 私钥(BASE64编码)* @return* @throws Exception*/public static byte[] encryptByPrivateKey(byte[] data, String privateKey) throws Exception {byte[] keyBytes = Base64Utils.decodeFromString(privateKey);PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(keyBytes);KeyFactory keyFactory = KeyFactory.getInstance(KEY_ALGORITHM);Key privateK = keyFactory.generatePrivate(pkcs8KeySpec);Cipher cipher = Cipher.getInstance(keyFactory.getAlgorithm());cipher.init(Cipher.ENCRYPT_MODE, privateK);int inputLen = data.length;ByteArrayOutputStream out = new ByteArrayOutputStream();int offSet = 0;byte[] cache;int i = 0;// 对数据分段加密while (inputLen - offSet > 0) {if (inputLen - offSet > MAX_ENCRYPT_BLOCK) {cache = cipher.doFinal(data, offSet, MAX_ENCRYPT_BLOCK);} else {cache = cipher.doFinal(data, offSet, inputLen - offSet);}out.write(cache, 0, cache.length);i++;offSet = i * MAX_ENCRYPT_BLOCK;}byte[] encryptedData = out.toByteArray();out.close();return encryptedData;}/** *//*** <p>* 获取私钥* </p>** @param keyMap 密钥对* @return* @throws Exception*/public static String getPrivateKey(Map<String, Object> keyMap) throws Exception {Key key = (Key) keyMap.get(PRIVATE_KEY);return Base64Utils.encodeToString(key.getEncoded());}/** *//*** <p>* 获取公钥* </p>** @param keyMap 密钥对* @return* @throws Exception*/public static String getPublicKey(Map<String, Object> keyMap) throws Exception {Key key = (Key) keyMap.get(PUBLIC_KEY);return Base64Utils.encodeToString(key.getEncoded());}/*** java端公钥加密*/public static String encryptedDataOnJava(String data, String PUBLICKEY) {try {data = Base64Utils.encodeToString(encryptByPublicKey(data.getBytes("UTF-8"), PUBLICKEY));} catch (Exception e) {// TODO Auto-generated catch block
            e.printStackTrace();}return data;}/*** java端私钥解密*/public static String decryptDataOnJava(String data, String PRIVATEKEY) {String temp = "";try {byte[] rs = Base64Utils.decodeFromString(data);temp = new String(RSAUtils.decryptByPrivateKey(rs, PRIVATEKEY), "UTF-8");} catch (Exception e) {e.printStackTrace();}return temp;}public static void main(String[] args) {String data = "hello";String s = encryptedDataOnJava(data, PUBLIC_KEY_CODE);System.out.println(s);}/** 解密 */static void doc() {String data = "hAvU3rwHjyl+qf9lx+yo4//hvVWtjxyvQQPmUAa7RbjBJGjdLALiaXwWn3aHqbfajoCJKE7zQDDpAkGtisd9M9hzvboGbZVJ++5vFDxrGMVk5nEd8JR/zZY361gihSLoY3OrBpAOWkWs1f0JD8oe5XADZcH0nM85/K831Iwa6zw=";String s = decryptDataOnJava(data, PRIVATE_KEY_CODE);System.out.println(s);}}

后端代码就不说了，自己理解下

 前台代码：

下面说下前端代码：在如下目录下导入这两个文件，同时在index的html中引入这两个文件：

jsencrypt.main.js链接：https://pan.baidu.com/s/1y0sqTlNrxj2wpKm6_iV7Ow
提取码：00yt

RSAExport.js文件链接：https://pan.baidu.com/s/11vRmNa0Ior35SXCYpDYutg
提取码：9rhq

 

在用到解密的地方使用：  declare var RSAUtil: any;  声明

需要加密或者解密的地方使用如下：

 

通过文件系统读取到文件内容，对文件内容进行解密；