java rsa非对称加密算法3个实例源代码

package com.zl.test3; import java.io.BufferedReader; import java.io.BufferedWriter; import java.io.ByteArrayOutputStream; import java.io.FileReader; import java.io.FileWriter; import java.io.IOException; import java.security.InvalidKeyException; 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.InvalidKeySpecException; import java.security.spec.PKCS8EncodedKeySpec; import java.security.spec.X509EncodedKeySpec; import javax.crypto.BadPaddingException; import javax.crypto.Cipher; import javax.crypto.IllegalBlockSizeException; import javax.crypto.NoSuchPaddingException; public class RSAEncrypt { /** * 字节数据转字符串专用集合 */ private static final char[] HEX_CHAR = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' }; /** * 随机生成密钥对 */ public static void genKeyPair(String filePath) { // KeyPairGenerator类用于生成公钥和私钥对，基于RSA算法生成对象 KeyPairGenerator keyPairGen = null; try { keyPairGen = KeyPairGenerator.getInstance("RSA"); } catch (NoSuchAlgorithmException e) { // TODO Auto-generated catch block e.printStackTrace(); } // 初始化密钥对生成器，密钥大小为96-1024位 keyPairGen.initialize(1024,new SecureRandom()); // 生成一个密钥对，保存在keyPair中 KeyPair keyPair = keyPairGen.generateKeyPair(); // 得到私钥 RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate(); // 得到公钥 RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic(); try { // 得到公钥字符串 String publicKeyString = Base64.encode(publicKey.getEncoded()); // 得到私钥字符串 String privateKeyString = Base64.encode(privateKey.getEncoded()); // 将密钥对写入到文件 FileWriter pubfw = new FileWriter(filePath + "/publicKey.keystore"); FileWriter prifw = new FileWriter(filePath + "/privateKey.keystore"); BufferedWriter pubbw = new BufferedWriter(pubfw); BufferedWriter pribw = new BufferedWriter(prifw); pubbw.write(publicKeyString); pribw.write(privateKeyString); pubbw.flush(); pubbw.close(); pubfw.close(); pribw.flush(); pribw.close(); prifw.close(); } catch (Exception e) { e.printStackTrace(); } } /** * 从文件中输入流中加载公钥 * * @param in * 公钥输入流 * @throws Exception * 加载公钥时产生的异常 */ public static String loadPublicKeyByFile(String path) throws Exception { try { BufferedReader br = new BufferedReader(new FileReader(path + "/publicKey.keystore")); String readLine = null; StringBuilder sb = new StringBuilder(); while ((readLine = br.readLine()) != null) { sb.append(readLine); } br.close(); return sb.toString(); } catch (IOException e) { throw new Exception("公钥数据流读取错误"); } catch (NullPointerException e) { throw new Exception("公钥输入流为空"); } } /** * 从字符串中加载公钥 * * @param publicKeyStr * 公钥数据字符串 * @throws Exception * 加载公钥时产生的异常 */ public static RSAPublicKey loadPublicKeyByStr(String publicKeyStr) throws Exception { try { byte[] buffer = Base64.decode(publicKeyStr); KeyFactory keyFactory = KeyFactory.getInstance("RSA"); X509EncodedKeySpec keySpec = new X509EncodedKeySpec(buffer); return (RSAPublicKey) keyFactory.generatePublic(keySpec); } catch (NoSuchAlgorithmException e) { throw new Exception("无此算法"); } catch (InvalidKeySpecException e) { throw new Exception("公钥非法"); } catch (NullPointerException e) { throw new Exception("公钥数据为空"); } } /** * 从文件中加载私钥 * * @param keyFileName * 私钥文件名 * @return 是否成功 * @throws Exception */ public static String loadPrivateKeyByFile(String path) throws Exception { try { BufferedReader br = new BufferedReader(new FileReader(path + "/privateKey.keystore")); String readLine = null; StringBuilder sb = new StringBuilder(); while ((readLine = br.readLine()) != null) { sb.append(readLine); } br.close(); return sb.toString(); } catch (IOException e) { throw new Exception("私钥数据读取错误"); } catch (NullPointerException e) { throw new Exception("私钥输入流为空"); } } public static RSAPrivateKey loadPrivateKeyByStr(String privateKeyStr) throws Exception { try { byte[] buffer = Base64.decode(privateKeyStr); PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(buffer); KeyFactory keyFactory = KeyFactory.getInstance("RSA"); return (RSAPrivateKey) keyFactory.generatePrivate(keySpec); } catch (NoSuchAlgorithmException e) { throw new Exception("无此算法"); } catch (InvalidKeySpecException e) { throw new Exception("私钥非法"); } catch (NullPointerException e) { throw new Exception("私钥数据为空"); } } /** * 公钥加密过程 * * @param publicKey * 公钥 * @param plainTextData * 明文数据 * @return * @throws Exception * 加密过程中的异常信息 */ public static byte[] encrypt(RSAPublicKey publicKey, byte[] data) throws Exception { if (publicKey == null) { throw new Exception("加密公钥为空, 请设置"); } Cipher cipher = null; try { // 使用默认RSA cipher = Cipher.getInstance("RSA"); cipher.init(Cipher.ENCRYPT_MODE, publicKey); 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 > 117) { cache = cipher.doFinal(data, offSet, 117); } else { cache = cipher.doFinal(data, offSet, inputLen - offSet); } out.write(cache, 0, cache.length); i++; offSet = i * 117; } byte[] encryptedData = out.toByteArray();