RSA算法工具类(纯JDK，无引入jar)wangxuelei036的博客-

 下面是RSA 生成公私钥 加解密 加签验签的功能类

由于计算能力的飞速发展，从安全性角度考虑，尽可能考虑RSA2,该算法在摘要算法上比 SHA1WithRSA 有更强的安全能力。

目前 SHA1WithRSA 的签名算法很多地方也提供支持，但为了您的应用安全，强烈建议使用 SHA256WithRSA 的签名算法。

keySize长度推荐 2048位

工具类 使用的 全部是 jdk自带jar 不需要引入其他包，附带基础测试，工具类使用的是RSA2 keysize 默认 2048，标准算法名称为

SHA256WithRSA 

 package utils;  import javax.crypto.Cipher; import java.security.*; import java.security.interfaces.RSAPrivateKey; import java.security.interfaces.RSAPublicKey; import java.security.spec.PKCS8EncodedKeySpec; import java.security.spec.X509EncodedKeySpec; import java.util.Base64;  /**  * @Author: 四灵  * @Description: RSA 非对称 加密解密 加签验签工具  * @Date: Created in 15:01 2016/4/9  */ @SuppressWarnings("all") public class RSAUtils {     //取值 SHA256WithRSA  或者 SHA1WithRSA     //RSA 对应 SHA1WithRSA     //RSA2 对应 SHA256WithRSA  至少2048 位以上     public static final String SHA_WITH_RSA_ALGORITHM = "SHA256WithRSA";      public static final String MD5_WITH_RSA = "MD5WithRSA";      public static final int KEY_SIZE_2048 = 2048;      public static final int KEY_SIZE_1024 = 1024;      public static final String  ALGORITHM = "RSA";      public static final String  CHARSET = "UTF-8";       /**      * SHAWithRSA签名      */     public static String sign(String in,String pivateKey,String algorithm) throws Exception{         PKCS8EncodedKeySpec priPKCS8 = new PKCS8EncodedKeySpec(Base64.getDecoder().decode(pivateKey));         KeyFactory keyf = KeyFactory.getInstance(ALGORITHM);         PrivateKey priKey = keyf.generatePrivate(priPKCS8);         Signature signa = Signature.getInstance(algorithm!=null?algorithm:SHA_WITH_RSA_ALGORITHM);         signa.initSign(priKey);         signa.update(in.getBytes());         byte[] signdata = signa.sign();         return Base64.getEncoder().encodeToString(signdata);     }      /**      * SHAWithRSA签名      * 默认 SHAWithRSA签名      */     public static String sign(String in,String pivateKey) throws Exception{         return sign(in,pivateKey,null);     }      /**      * SHAWithRSA验签      * 默认SHAWithRSA验签      */     public static boolean isValid(String in,String signData,String publicKey,String algorithm) throws Exception{         KeyFactory keyFactory = KeyFactory.getInstance(ALGORITHM);         byte[] encodedKey = Base64.getDecoder().decode(publicKey);         PublicKey pubKey = keyFactory.generatePublic(new X509EncodedKeySpec(encodedKey));   Signature signa = Signature.getInstance(algorithm!=null?algorithm:SHA_WITH_RSA_ALGORITHM);         signa.initVerify(pubKey);         signa.update(in.getBytes());         byte[] sign_byte = Base64.getDecoder().decode(signData);         boolean flag = signa.verify(sign_byte);         return flag;     }      /**      *  SHAWithRSA验签      */     public static boolean isValid(String in,String signData,String publicKey) throws Exception{         return isValid(in,signData,publicKey,null);     }      /**      * RSA公钥加密      */     public static String encrypt( String str, String publicKey) throws Exception{         //base64编码的公钥         byte[] decoded = Base64.getDecoder().decode(publicKey);         RSAPublicKey pubKey = (RSAPublicKey) KeyFactory.getInstance(ALGORITHM).generatePublic(new X509EncodedKeySpec(decoded));         //RSA加密         Cipher cipher = Cipher.getInstance(ALGORITHM);         cipher.init(Cipher.ENCRYPT_MODE, pubKey);         String outStr = Base64.getEncoder().encodeToString(cipher.doFinal(str.getBytes(CHARSET)));         return outStr;     }      /**      * RSA私钥解密      */     public static String decrypt(String str, String privateKey) throws Exception{         //64位解码加密后的字符串         byte[] inputByte = java.util.Base64.getDecoder().decode(str.getBytes(CHARSET));         //base64编码的私钥         byte[] decoded = Base64.getDecoder().decode(privateKey);         RSAPrivateKey priKey = (RSAPrivateKey) KeyFactory.getInstance(ALGORITHM).generatePrivate(new PKCS8EncodedKeySpec(decoded));         //RSA解密         Cipher cipher = Cipher.getInstance(ALGORITHM);         cipher.init(Cipher.DECRYPT_MODE, priKey);         String outStr = new String(cipher.doFinal(inputByte));         return outStr;     }      /**      * 随机生成密钥对      * 也可以用阿里的生成工具      */     public static void genKeyPair(Integer keySize) throws NoSuchAlgorithmException {         //推荐 2048位以上，保证安全性         if(keySize==null){             keySize = KEY_SIZE_2048;         }         // KeyPairGenerator类用于生成公钥和私钥对，基于RSA算法生成对象         KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance(ALGORITHM);         // 初始化密钥对生成器，密钥大小为96-1024位         keyPairGen.initialize(keySize, new SecureRandom());         // 生成一个密钥对，保存在keyPair中         KeyPair keyPair = keyPairGen.generateKeyPair();         RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();   // 得到私钥         RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();  // 得到公钥         String publicKeyString = new String(Base64.getEncoder().encode(publicKey.getEncoded()));         // 得到私钥字符串         String privateKeyString = new String(Base64.getEncoder().encode(privateKey.getEncoded()));         // 将公钥和私钥保存到Map         System.out.println("公钥:"+publicKeyString);         System.out.println("私钥:"+privateKeyString);     }      //简单测试     public static void main(String[] args) throws Exception {         String content = "我的数据";         //支付宝RSA生成的公私钥 也同样适用，可以自行尝试         genKeyPair(null);         String publicKey = "MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAkGv/70Te42PS5fyuLCNr/UiMtDqhasMZpmA92aDTWjh9RT5r4Kl3sKRO63RitWuEgFAZHljJUB9afEzWnP+EGpkeiq3SMpIfpUWy89nqZxUUyOg6aIvfEZBjKFFc3umM9uasFTLC8l4NCfDnlkpHxwQjc5emUGJ5ZnqqGOmrdP5se7dyO7QEtdI7/jfbzPDmMeWyegWE5iN8CHJh2V0foBur7gS/syTnbLFcRr3wzsbXh9RyLP9OMmHx9MO1fhTOnTZnN+xWXNggTgymoUM27+bZd/nrKaZNeUF50DIyTFEe6yqwkbtVf2jeR+CNjcWO+uP7CvTpDKk+9h3DZyZ5RwIDAQAB";         String privateKey = "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";         /*加解密测试*/         String encryptContent = RSAUtils.encrypt(content, publicKey);         System.out.println("加密后数据:n" + encryptContent);         String decryptContent = RSAUtils.decrypt(encryptContent,privateKey);         System.out.println("解密后数据:n"+decryptContent);         /*加签验签测试*/         String signOriginalContent = "验签功能测试";         String geneSignContent = RSAUtils.sign(signOriginalContent, privateKey);         System.out.println("生成的签名:n"+geneSignContent);         boolean valid = RSAUtils.isValid(signOriginalContent,geneSignContent, publicKey);         System.out.println("结果验签:n"+valid);     } }