概述

非對(duì)稱加密算法與對(duì)稱加密算法的主要差別在于非對(duì)稱加密算法用于加密和解密的密鑰不相同，非對(duì)稱加密算法密鑰分為公鑰和私鑰，公鑰加密只能用私鑰解密，反之私鑰加密只能用公鑰解密。相比對(duì)稱加密算法，非對(duì)稱加密算法加/解密效率低，但安全性高，這兩種算法一般結(jié)合使用。常見非對(duì)稱加密算法有RSA、ECC、Elgamal等。

使用RSA實(shí)現(xiàn)加密解密

公鑰加密，私鑰解密。

package com.ss.utils;import javax.crypto.Cipher;import java.security.KeyFactory;import java.security.KeyPair;import java.security.KeyPairGenerator;import java.security.NoSuchAlgorithmException;import java.security.spec.PKCS8EncodedKeySpec;import java.security.spec.X509EncodedKeySpec;import java.util.Base64;import java.util.HashMap;import java.util.Map;public class RsaUtil { public static final String KEY_TYPE_PRIVATE_KEY = 'privateKey'; public static final String KEY_TYPE_PUBLIC_KEY = 'publicKey'; /** * 生成公鑰和私鑰 * * @return * @throws NoSuchAlgorithmException */ public static Map<String, String> generateKey() throws NoSuchAlgorithmException { Map<String, String> resultMap = new HashMap<>(); KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance('RSA'); KeyPair keyPair = keyPairGenerator.generateKeyPair(); Base64.Encoder encoder = Base64.getEncoder(); resultMap.put(KEY_TYPE_PRIVATE_KEY, encoder.encodeToString(keyPair.getPrivate().getEncoded())); resultMap.put(KEY_TYPE_PUBLIC_KEY, encoder.encodeToString(keyPair.getPublic().getEncoded())); return resultMap; } /** * RSA加密 * @param key * @param content * @param keyType * @return * @throws Exception */ public static String rsaEncrypt(String key, String content, String keyType) throws Exception { return rsa(key, content.getBytes(), keyType, Cipher.ENCRYPT_MODE); } /** * RSA解密 * @param key * @param content * @param keyType * @return * @throws Exception */ public static String rsaDecrypt(String key, String content, String keyType) throws Exception { return rsa(key, Base64.getDecoder().decode(content), keyType, Cipher.DECRYPT_MODE); } private static String rsa(String key, byte[] content, String keyType, int mode) throws Exception { Cipher cipher = Cipher.getInstance('RSA'); KeyFactory keyFactory = KeyFactory.getInstance('RSA'); if (KEY_TYPE_PRIVATE_KEY.equals(keyType)) { cipher.init(mode, keyFactory.generatePrivate(new PKCS8EncodedKeySpec(Base64.getDecoder().decode(key)))); } else { cipher.init(mode, keyFactory.generatePublic(new X509EncodedKeySpec(Base64.getDecoder().decode(key)))); } byte[] bytes = cipher.doFinal(content); return mode == Cipher.DECRYPT_MODE ? new String(bytes) : Base64.getEncoder().encodeToString(bytes); } public static void main(String[] args) throws Exception { String content = '大王叫我來巡山吶'; //生成密鑰對(duì) Map<String, String> keyMap = generateKey(); System.out.println('私鑰：' + keyMap.get(KEY_TYPE_PRIVATE_KEY)); System.out.println('公鑰：' + keyMap.get(KEY_TYPE_PUBLIC_KEY)); //私鑰加密，公鑰解密 String privateKeyData = rsaEncrypt(keyMap.get(KEY_TYPE_PRIVATE_KEY), content, KEY_TYPE_PRIVATE_KEY); System.out.println('私鑰加密：' + privateKeyData); System.out.println('公鑰解密：' + rsaDecrypt(keyMap.get(KEY_TYPE_PUBLIC_KEY), privateKeyData, KEY_TYPE_PUBLIC_KEY)); //公鑰加密，私鑰解密 String publicKeyData = rsaEncrypt(keyMap.get(KEY_TYPE_PUBLIC_KEY), content, KEY_TYPE_PUBLIC_KEY); System.out.println('公鑰加密：' + publicKeyData); System.out.println('私鑰解密：' + rsaDecrypt(keyMap.get(KEY_TYPE_PRIVATE_KEY), publicKeyData, KEY_TYPE_PRIVATE_KEY)); }}

輸出

私鑰：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公鑰：MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA0D2Z49Pv7oeYxtP66lbFyi73u8E8Ni1RMHQYZvkj6y6B2G+PuonTXheG1oE6jUbNoX3sKuXMosF7o0/nqqdINXm0i1klFswbJLcp0DIIMW/CMLZxWM5mV+wUgFLna3063u+EbSktJK2GOTwlwhkfxBm21zFb9ZtkufQa5FhCPHP4jkYUQCef6akVv+dXCIpj8fYk2Mf0GQuFbAkYvGawWl3CYRIuGP2MzhYXyEyA+AE4rNGd8sNxVcmysyaNzXsbqXHnOamiwZcLg5GOhODYEKudW4wQlAe/EYFxS3WlbXwbvVa+6UXaq4e7A//5KYonI4iyb5nCxvXoF65B0ZZtkwIDAQAB私鑰加密：V9kG4o3nceI4a19t/V5431v9Ek1PiV3FZokfnRNBor/RBymwDX4rsGNHEYuyN6/sbbD56r3ij5tUpShXFlcHrzVH4IfD4ySbvNNeMs2FrZLF3zvQmwRKDPH6SJ0DEczi5N97Vfh4b2tfyLT8iX3t9LPWgEj5mB7MXiYPc56mza+ZAqDduxWWsm6Emm81uKn97wZnasg8zXlDbhRttVTWhszbDhrFqsgd2sb8ZZUZIuiGTaIg7U6Slc5x9uS3UVACXXVyMCmxiVutQtg3Z4kt80ruh7xO0hl4cWk6P2Tg0ncaIQn/5vKsO2UXr/EsCb2rchWN3ZBHTVyQ83v/EHDtQw==公鑰解密：大王叫我來巡山吶公鑰加密：aartOyClfEIz1JT5nghpTbXxLZEOovm+vwvg+u3Tw8t5LOF+C7Gg/uxUP8Hm5jEkN6JfBHaMWTKg0RQ2xf3CCuXcLIpYVCOUwADwd05E8guEfZBT8FIp8jghCz2j+lAIiTfGZvsK9qUdZEmwTAEjV6uP4avF6njriglGJ4KhcYXEO66tOJWe2nQ1hyYXEHS43h9F0dtlWDjF6Xr6wdmUALnhprHDwKPdT/1T8p7+M5Fz7fUC7TJulBHWCSZvhgl405PvN+iTv7VysBJKRPks1JnmMe6BxFyhxXZfNRHmUyQvTMSfWt/A5gOy8ao/SOwWv0QMSh5NbocSd/tpjn27kw==私鑰解密：大王叫我來巡山吶

使用RSA實(shí)現(xiàn)數(shù)字簽名

私鑰簽名，公鑰驗(yàn)證。

package com.ss.utils;import java.security.*;import java.security.spec.PKCS8EncodedKeySpec;import java.security.spec.X509EncodedKeySpec;import java.util.Base64;import java.util.HashMap;import java.util.Map;public class SignatureUtil { public static final String KEY_TYPE_PRIVATE_KEY = 'privateKey'; public static final String KEY_TYPE_PUBLIC_KEY = 'publicKey'; /** * 生成公鑰和私鑰 * * @return * @throws NoSuchAlgorithmException */ public static Map<String, String> generateKey() throws NoSuchAlgorithmException { Map<String, String> resultMap = new HashMap<>(); KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance('RSA'); KeyPair keyPair = keyPairGenerator.generateKeyPair(); Base64.Encoder encoder = Base64.getEncoder(); resultMap.put(KEY_TYPE_PRIVATE_KEY, encoder.encodeToString(keyPair.getPrivate().getEncoded())); resultMap.put(KEY_TYPE_PUBLIC_KEY, encoder.encodeToString(keyPair.getPublic().getEncoded())); return resultMap; } /** * 私鑰簽名 * @param privateKeyStr * @param content * @return * @throws Exception */ public static String generateSignature(String privateKeyStr, String content) throws Exception { KeyFactory keyFactory = KeyFactory.getInstance('RSA'); Signature signature = Signature.getInstance('SHA1withRSA'); PrivateKey privateKey = keyFactory.generatePrivate(new PKCS8EncodedKeySpec(Base64.getDecoder().decode(privateKeyStr))); signature.initSign(privateKey); signature.update(content.getBytes()); return Base64.getEncoder().encodeToString(signature.sign()); } /** * 公鑰驗(yàn)證 * @param publicKeyStr * @param content * @param sign * @return * @throws Exception */ public static boolean verifySignature(String publicKeyStr, String content, String sign) throws Exception { KeyFactory keyFactory = KeyFactory.getInstance('RSA'); Signature signature = Signature.getInstance('SHA1withRSA'); PublicKey publicKey = keyFactory.generatePublic(new X509EncodedKeySpec(Base64.getDecoder().decode(publicKeyStr))); signature.initVerify(publicKey); signature.update(content.getBytes()); return signature.verify(Base64.getDecoder().decode(sign)); } public static void main(String[] args) throws Exception { String content = '大王叫我來巡山吶'; //生成密鑰對(duì) Map<String, String> keyMap = generateKey(); //私鑰簽名 String sign = generateSignature(keyMap.get(KEY_TYPE_PRIVATE_KEY), content); System.out.println('私鑰簽名：' + sign); //公鑰驗(yàn)證 boolean verifyResult = verifySignature(keyMap.get(KEY_TYPE_PUBLIC_KEY), content, sign); System.out.println('公鑰驗(yàn)證：' + verifyResult); //將內(nèi)容做下修改，再進(jìn)行公鑰驗(yàn)證 boolean verifyResult2 = verifySignature(keyMap.get(KEY_TYPE_PUBLIC_KEY), content + '啦啦啦啦', sign); System.out.println('公鑰驗(yàn)證：' + verifyResult2); }}

輸出

私鑰簽名：XDWeOUVZhXNPl58mcmRK8ht9TAhnREc+NlnSs2b6PCJuj29ABuoXsjZeJqSspGw8hm9ckHVSTrUt8pX4BFBFzrINDRBsx3TdLp2L8nMkhjFUfo0qcyZo8ReEGFCNr0ergkq2W1Me/5W40GrQz4cJcQ4KV/QWzD8YHWcnDvKg9Q0nXJSngyhJTzUB8o/pgo/tmkA9+bWW212UD9nzEXu5aoPEcYyoo3iFWRX5o9Jgg6ZF+exmWizwZHkg4eD1zC5IN3m4yRS6GRbnZInEuDsOMp9W7HouDLUirkFZiSkyW+DVto+L6CE5eNBrWC52zxiNkVBlkyYKOatSpcrQrtnyiQ==公鑰驗(yàn)證：true公鑰驗(yàn)證：false

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