java结合keytool如何实现非对称加密与解密详解

$ keytool -genkey - alias signLegal -keystore examplestanstore2 -validity 1800 -keyalg RSA

$ keytool -list -keystore examplestanstore2 - v

$ keytool - export -keystore examplestanstore2 - alias signLegal - file StanSmith.crt -rfc

import java.io.*;

import java.security.KeyStore;

import java.security.PrivateKey;

import java.security.PublicKey;

import javax.crypto.Cipher;

import sun.security.provider.*;

public class RSAEntry {

  public static void main(String[] args) {

  try {

  //1.从密钥库中取私钥

  KeyStore ks = KeyStore.getInstance( "JKS" );

  FileInputStream ksfis = new FileInputStream( "examplestanstore2" );

  BufferedInputStream ksbufin = new BufferedInputStream(ksfis);

  // open keystore and get private key

  // alias is 'signLeal', kpasswd/spasswd is 'vagrant'

  ks.load(ksbufin, "vagrant" .toCharArray());

  PrivateKey prikey = (PrivateKey) ks.getKey( "signLegal" , "vagrant" .toCharArray());

  //2.根据命令行参数取公钥

  FileInputStream certfis = new FileInputStream(args[ 0 ]);

  java.security.cert.CertificateFactory cf =

   java.security.cert.CertificateFactory.getInstance( "X.509" );

  java.security.cert.Certificate cert = cf.generateCertificate(certfis);

  PublicKey pubKey = cert.getPublicKey();

  //3.使用公钥进行加密

  String data = "测试数据" ;

  //构建加密解密类

  Cipher cipher = Cipher.getInstance( "RSA" );

  cipher.init(Cipher.ENCRYPT_MODE, pubKey); //设置为加密模式

  byte [] jmdata = cipher.doFinal(data.getBytes());

  //打印加密后数据

  System.out.println(bytesToHexString(jmdata));

  //改为解密模式进行解密

  cipher.init(Cipher.DECRYPT_MODE, prikey); //会用私钥解密

  jmdata = cipher.doFinal(jmdata);

  System.out.println( new String(jmdata));

  } catch (Exception e) {

   e.printStackTrace();

  }

  }

  //这个方法用于把二进制转换成ASCII字符串。

  public static String bytesToHexString( byte [] bytes) {

  if (bytes == null )

   return "null!" ;

  int len = bytes.length;

  StringBuilder ret = new StringBuilder( 2 * len);

  for ( int i = 0 ; i < len; ++i) {

   int b = 0xF & bytes[(i)] >> 4 ;

   ret.append( "0123456789abcdef" .charAt(b));

   b = 0xF & bytes[(i)];

   ret.append( "0123456789abcdef" .charAt(b));

  }

  return ret.toString();

  }

}

$ javac RSAEntry.java

$ java RSAEntry StanSmith.crt

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

测试数据