RSA分段加密 - Java javarsa

前言 RSA的 key 长度为 1024 用公钥加密比较长的字符串时会异常，这里介绍 java 如何对长文本进行分段加密，附上其它链接
RSA加密 - Java
RSA加密 - Vue
RSA分段解密 - Vue

具体实现

实现类

import com.alibaba.fastjson.JSONObject; import org.apache.commons.lang3.ArrayUtils; import javax.crypto.Cipher; import java.io.ByteArrayOutputStream; import java.net.URLDecoder; import java.net.URLEncoder; import java.security.KeyFactory; import java.security.PrivateKey; import java.security.PublicKey; import java.security.spec.EncodedKeySpec; import java.security.spec.PKCS8EncodedKeySpec; import java.security.spec.X509EncodedKeySpec; import java.util.Base64; import java.util.HashMap; import java.util.Map; public class RSAUtils {/** * 公钥 */ private static final String PUBLIC_KEY = "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCaaI4MBywkCjIppZnraqN3pbrcZTq/t0+aMBo8K3pK9BDD6XkM6N2Yfcva7BSFbUWuAcI7piXak0UKn9CElDuhNzUSgQn4IXKxIt3Iva5cV83qYumj+0yRjjLT8Muu1Y1rgBZjY9oBwhVoV+Twg25+UJ+6Q6HM4xTwQQJDoyy4jwIDAQAB"; /** * 私钥 */ private static final String PRIVATE_KEY = "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"; /** * 私钥分段加密 * @param content * @return * @throws Exception */ public static String encryptLongByPrivateKey(String content) throws Exception { // 获取私钥 PrivateKey privateKey = getPrivateKey(PRIVATE_KEY); Cipher cipher = Cipher.getInstance("RSA"); cipher.init(Cipher.ENCRYPT_MODE, privateKey); // URLEncoder编码解决中文乱码问题 byte[] data = https://www.it610.com/article/URLEncoder.encode(content,"UTF-8").getBytes("UTF-8"); // 加密时超过117字节就报错。为此采用分段加密的办法来加密 byte[] enBytes = null; for (int i = 0; i < data.length; i += 117) { // 注意要使用2的倍数，否则会出现加密后的内容再解密时为乱码 byte[] doFinal = cipher.doFinal(ArrayUtils.subarray(data, i, i + 117)); enBytes = ArrayUtils.addAll(enBytes, doFinal); } return Base64.getEncoder().encodeToString(enBytes); }/** * 公钥分段解密 * @param content * @return * @throws Exception */ public static String decryptLongByPublicKey(String content) throws Exception { //获取公钥 PublicKey publicKey = getPublicKey(PUBLIC_KEY); Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding"); cipher.init(Cipher.DECRYPT_MODE, publicKey); byte[] data =https://www.it610.com/article/Base64.getDecoder().decode(content); // 返回UTF-8编码的解密信息 int inputLen = data.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 > 128) { cache = cipher.doFinal(data, offSet, 128); } else { cache = cipher.doFinal(data, offSet, inputLen - offSet); } out.write(cache, 0, cache.length); i++; offSet = i * 128; } byte[] decryptedData = https://www.it610.com/article/out.toByteArray(); out.close(); return URLDecoder.decode(new String(decryptedData,"UTF-8")); }/** * 将base64编码后的公钥字符串转成PublicKey实例 * @param publicKey 公钥 * @return PublicKey实例 * @throws Exception 异常信息 */ public static PublicKey getPublicKey(String publicKey) throws Exception { EncodedKeySpec keySpec = new X509EncodedKeySpec(Base64.getDecoder().decode(publicKey)); KeyFactory keyFactory = KeyFactory.getInstance("RSA"); return keyFactory.generatePublic(keySpec); }/** * 将base64编码后的私钥字符串转成PrivateKey实例 * @param privateKey 私钥 * @return PrivateKey实例 * @throws Exception 异常信息 */ private static PrivateKey getPrivateKey(String privateKey) throws Exception { byte[] keyBytes = Base64.getDecoder().decode(privateKey); PKCS8EncodedKeySpec keySpec = new PKCS8EncodedKeySpec(keyBytes); KeyFactory keyFactory = KeyFactory.getInstance("RSA"); return keyFactory.generatePrivate(keySpec); }public static void main(String[] args) throws Exception {Map map = new HashMap<>(); map.put("name", "Cosini"); map.put("phone", "13888888888"); String content = JSONObject.toJSONString(map); // 密文 String cipherText = RSAUtils.encryptLongByPrivateKey(content); System.out.println("cipherText: " + cipherText); // 明文 String plainText = RSAUtils.decryptLongByPublicKey(cipherText); System.out.println("plainText: " + plainText); }}