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  Signature sign/verification demo in Java

Digital signature is commonly used in areas where data authentication and integrity are required. It is extremely important to have signature while transferring sensitive data from one peer to other peers through network since there might be malicious applications or man-in-the-middle attacks which may alter the data along the way. Java provides some APIs to generate and verify digital signature. One important class is Signature.  When generating the signature, a private key needs to be pa...

   SECURITY,JAVA,SIGNATURE     2015-11-21 09:48:12

  A HTTPS client and HTTPS server demo in Java

In this post, I will create a HTTPS server and HTTPS client demo which can establish HTTPS communication between a server and a client using Java. This should be very useful when we want to test our understanding about SSL communication. We will use both a detailed SSL client and a simple HttpsURLConnection as the HTTPS client. Before creating the actual HTTPS server and HTTPS client, we first need to generate the keystore and truststore to be used by the server and client. To generate the keyst...

   SSL,HTTPS,JAVA,DEMO     2015-10-23 09:04:36

  Access control in Java -- doPrivileged

Previously we have introduced how Java performs permission check to protect resource access. What if sometimes we need to give some class the temporary access to some resource which it initially doesn't have? AccessController provides six doPrivileged methods to fulfill this requirement. These six methods have below signatures : static T doPrivileged(PrivilegedAction action)static T doPrivileged(PrivilegedAction action, AccessControlContext context)static T doPrivileged(PrivilegedExceptionA...

   JAVA,SECURITY,DOPRIVILEGED     2016-03-08 05:46:42

  What does super.clone() do?

Object class has a protected clone() method declared to make it possible for all classes make a clone of itself when needed. The clone() is often used when a new instance of the class is needed while at the same time to maintain the same state as the original object. Any class which wants to have clone enabled has to implement the marker interface Cloneable. If a class which implements Cloneable doesn't override the Object.clone() method, the Object.clone() method will be called to just make a b...

   Cloneable,super.clone(),clone,Java     2015-01-07 05:25:52

  Using MemoryMappedBuffer to handle large file in Java

When handling large files, it will largely affect the process speed while using traditional FileInputStream, FileOutputStream or RandomAccessFile since they trigger lots of read and write operations. In Java NIO, a new way of handling large file is introduced which is to use MmeoryMappedBuffer to create memory mapped file. Memory-mapped I/O uses the filesystem to establish a virtual memory mapping from user space directly to the applicable filesystem pages. With a memory-mapped file, you can pre...

   JAVA,IO,NIO     2015-11-13 01:58:08

  Guide for installing Ubuntu in VirtualBox on Windows

Have you ever tried to have two OSs installed on your PC? Do you want to try out the new Ubuntu system? If you do want to use Ubuntu when at the same time you are using Windows, you may want to install your Ubuntu in an VirtualBox. In this post, we will show you how to install Ubuntu in VirtualBox on Windows. Pre-requisites VirtualBox -- You can download it from Oracle. Ubuntu -- You can download it from here. Please note it should be an ISO file The Ubuntu used in this post is Ubuntu 12.04 LT...

   Ubuntu,Windows,VirtualBox     2014-01-15 03:21:05

  How do Silicon Valley companies recruit

There are a lot of friends asking me about the basic flow of how Silicon Valley companies recruit engineers. As a candidate, I tried Facebook, Google, Yahoo, Oracle, and I received offer from all these companies. As an interviewer, I have interviewed no less than 300 people and I know about the process of recruitment. I write this article with the hope of inspiring people who want to go to Silicon Valley or who are preparing for interviews or who are in the design of the recruiting process...

   Facebook,Interview,Experience,Silicon Valley     2012-05-15 06:36:52

  Products born for Cloud

Cloud computing has become increasingly popularity among companies. It greatly saves the investment of infrastructure and training with everything is running on cloud, it also improves the accessibility and flexibility of service provided by companies. With its popularity, many products are born or becoming popular to help build and move the apps to the cloud. Some well known names of these products are Vagrant, Docker/LXC, Chef and OpenStack. These tools can help create, test and deploy applica...

   Cloud,Openstack,Docker,Vargrant,LXC,Chef     2015-01-25 02:27:11

  Using keytool to create certificate chain

JDK provides a command line tool -- keytool to handle key and certificate generation. This tool has a set of options which can be used to generate keys, create certificates, import keys, install certificate and export certificates etc. In this tutorial, we will show how to create certificate chain using keytool. If you want to understand how to create certificate chain programmably, please refer to Generate certificate in Java -- Certificate chain. To begin, we first generate a key pair whi...

   JAVA,KEYTOOL,CERTIFICATE CHAIN,CERTIFICATE     2015-12-17 07:09:33

  Generating CSR using Java

A CSR(Certificate Signing Request) is a kind of request generated by an application and is to be sent to a Certificate Authority to create a signed certificate which can be distributed. It usually contains certificate information such as subject name, public key info and signature info. In Java, keytool can be used to generate a certificate request with option -certreq.  But sometimes if an application wants to create a CSR programmatically, keytool will not do a favor, instead you should u...

   JAVA,SECURITY,CSR,CERTIFICATE REQUEST     2016-05-25 04:49:17

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