公鑰加密算法，也就是 非對(duì)稱加密算法，這種算法加密和解密的密碼不一樣，一個(gè)是公鑰，另一個(gè)是私鑰：

公鑰和私鑰成對(duì)出現(xiàn) 公開(kāi)的密鑰叫公鑰，只有自己知道的叫私鑰 用公鑰加密的數(shù)據(jù)只有對(duì)應(yīng)的私鑰可以解密 用私鑰加密的數(shù)據(jù)只有對(duì)應(yīng)的公鑰可以解密 如果可以用公鑰解密，則必然是對(duì)應(yīng)的私鑰加的密 如果可以用私鑰解密，則必然是對(duì)應(yīng)的公鑰加的密

公鑰和私鑰是相對(duì)的，兩者本身并沒(méi)有規(guī)定哪一個(gè)必須是公鑰或私鑰。

代碼如下

package com.cxy.template.controller.keyTools;import java.util.Base64;import javax.crypto.Cipher;import java.security.KeyFactory;import java.security.KeyPair;import java.security.KeyPairGenerator;import java.security.NoSuchAlgorithmException;import java.security.SecureRandom;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;/** * Java RSA 加密工具類(lèi) * */public class RSAUtils { /** * 密鑰長(zhǎng)度 于原文長(zhǎng)度對(duì)應(yīng) 以及越長(zhǎng)速度越慢 */ private final static int KEY_SIZE = 1024; /** * 用于封裝隨機(jī)產(chǎn)生的公鑰與私鑰 */ private static Map<Integer, String> keyMap = new HashMap<Integer, String>(); /** * 隨機(jī)生成密鑰對(duì) */ public static void genKeyPair() throws NoSuchAlgorithmException { // KeyPairGenerator類(lèi)用于生成公鑰和私鑰對(duì)，基于RSA算法生成對(duì)象 KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance('RSA'); // 初始化密鑰對(duì)生成器 keyPairGen.initialize(KEY_SIZE, new SecureRandom()); // 生成一個(gè)密鑰對(duì)，保存在keyPair中 KeyPair keyPair = keyPairGen.generateKeyPair(); // 得到私鑰 RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate(); // 得到公鑰 RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic(); String publicKeyString = Base64.getEncoder().encodeToString(publicKey.getEncoded()); // 得到私鑰字符串 String privateKeyString = Base64.getEncoder().encodeToString(privateKey.getEncoded()); // 將公鑰和私鑰保存到Map //0表示公鑰 keyMap.put(0, publicKeyString); //1表示私鑰 keyMap.put(1, privateKeyString); } /** * RSA公鑰加密 * * @param str 加密字符串 * @param publicKey 公鑰 * @return 密文 * @throws Exception 加密過(guò)程中的異常信息 */ public static String encrypt(String str, String publicKey) throws Exception { //base64編碼的公鑰 byte[] decoded = Base64.getDecoder().decode(publicKey); RSAPublicKey pubKey = (RSAPublicKey) KeyFactory.getInstance('RSA').generatePublic(new X509EncodedKeySpec(decoded)); //RSA加密 Cipher cipher = Cipher.getInstance('RSA'); cipher.init(Cipher.ENCRYPT_MODE, pubKey); String outStr = Base64.getEncoder().encodeToString(cipher.doFinal(str.getBytes('UTF-8'))); return outStr; } /** * RSA私鑰解密 * * @param str 加密字符串 * @param privateKey 私鑰 * @return 明文 * @throws Exception 解密過(guò)程中的異常信息 */ public static String decrypt(String str, String privateKey) throws Exception { //64位解碼加密后的字符串 byte[] inputByte = Base64.getDecoder().decode(str); //base64編碼的私鑰 byte[] decoded = Base64.getDecoder().decode(privateKey); RSAPrivateKey priKey = (RSAPrivateKey) KeyFactory.getInstance('RSA').generatePrivate(new PKCS8EncodedKeySpec(decoded)); //RSA解密 Cipher cipher = Cipher.getInstance('RSA'); cipher.init(Cipher.DECRYPT_MODE, priKey); String outStr = new String(cipher.doFinal(inputByte)); return outStr; } public static void main(String[] args) throws Exception { long temp = System.currentTimeMillis(); //生成公鑰和私鑰 genKeyPair(); //加密字符串 System.out.println('公鑰:' + keyMap.get(0)); System.out.println('私鑰:' + keyMap.get(1)); System.out.println('生成密鑰消耗時(shí)間:' + (System.currentTimeMillis() - temp) / 1000.0 + '秒'); //客戶id + 授權(quán)時(shí)間 + 所用模塊 String message = '4028138151b3cf300151b419df090007' + '2015-12-17 11:30:22' + 'A01,A02'; System.out.println('原文:' + message); temp = System.currentTimeMillis(); //通過(guò)原文，和公鑰加密。 String messageEn = encrypt(message, keyMap.get(0)); System.out.println('密文:' + messageEn); System.out.println('加密消耗時(shí)間:' + (System.currentTimeMillis() - temp) / 1000.0 + '秒'); temp = System.currentTimeMillis(); //通過(guò)密文，和私鑰解密。 String messageDe = decrypt(messageEn, keyMap.get(1)); System.out.println('解密:' + messageDe); System.out.println('解密消耗時(shí)間:' + (System.currentTimeMillis() - temp) / 1000.0 + '秒'); }}

測(cè)試如下

公鑰:MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCtI8/X2ayQNXsz6/HTJew8z86+aevsJJLNS5dT74/zUwfaOpouInMQLwhqLFvMoCIzw2CLdG7/hwx3HGlKTHDpaTCqnKu17NVOriI8o7lAgI6pK/L2M8kpkbAG88XBmH6aNbi94TS1/ljsS9jMNoEQvfLC2A/KUw9sopRg73gAawIDAQAB私鑰: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生成密鑰消耗時(shí)間:0.129秒原文:4028138151b3cf300151b419df0900072015-12-17 11:30:22A01,A02密文:DnNGSArBjHQ46uyP9aBBs/f+zGwbpM2suh39Imdqu1ebUyCdB6b1AYB8Y7snklttm++EQjrKO8B+06er0+bOJb8lXbHQrvDkFCbcp31TiCBeITZT8bWpHQfwVmutVYKCYGwuk2E5VXQfSySuh6ZsUX/M/3UfS9MvKbQB3d1dyJ8=加密消耗時(shí)間:0.217秒解密:4028138151b3cf300151b419df0900072015-12-17 11:30:22A01,A02解密消耗時(shí)間:0.003秒Process finished with exit code 0

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