Welcome!

Java IoT Authors: Yeshim Deniz, Roger Strukhoff, Carmen Gonzalez, Elizabeth White, Stefan Bernbo

Related Topics: Java IoT

Java IoT: Article

Using Self-Signed Certificates for Web Service Security

How to compete with trusted certificate authorities

One of the great things about the Java programming language is the Open Source community that provides great applications at little or no cost. An example of this is Apache Tomcat, which provides a solid Web server for development using servlet or JSP technology. Now that Web Service technology is maturing there's a potential for a whole scenario of applications to take advantage of a Swing feature-rich thin client on the front-end coupled to the data verification and business logic already developed in the Web or ejb tier. Such applications are only viable if they can be secure, however, security doesn't have to come at a great cost. The purpose of this article is to demonstrate how Web Service clients can use self-signed security certificates over the secure HTTPS protocol.

The Problem with Using Self-Signed Certificates
HTTPS typically works seamlessly with the non-secure HTTP protocol and doesn't interrupt the user's experience. This is because SSL certificates are designed to be verified and signed by a trusted third party. Verisign is a popular certificate authority. If a Web application requires secure communication, you can pay Verisign to sign your SSL certificate. Once Verisign does that, users on your Web site can switch between HTTP and HTTPS without interruption because all major Web browsers trust certificates signed by Verisign. Verisign is not the only option for getting certificates signed. To save operating costs, or for personal use, you can self-sign your own certificate. However, self-signing your certificate will interrupt your Web site user's experience. Typically the Web browser will display a dialog box asking if you want to trust a certificate you signed.

Web browsers are nice because when they get a certificate signed by an unknown certificate authority there's an option to proceed. When developing Web Service clients for communication over HTTPS it's not so easy. When running Java code there's no dialog box asking about trusting a distrusted certificate authority. The JRE will throw an exception trying to connect over HTTPS to a Web site with a distrusted certificate:

Caused by: sun.security.validator.ValidatorException: No trusted certificate found

There's no way to catch this exception and continue. To get the Web Service to work with a self-signed certificate the JRE has to somehow trust you as a certificate authority.

Solution Outline
To demonstrate a solution to this problem I'll do the following:

  1. Generate and self-sign my own certificate
  2. Configure Tomcat for SSL and make it use that certificate
  3. Create an example Web Service to be called over HTTPS
  4. Generate Web Service client code from WSDL
  5. Demonstrate a client using a custom keystore solution
Generating a Self-Signed Certificate
The JDK comes with a tool, keytool.exe, that is used to mange SSL public/private keys. Keys are added and removed from a binary file on the file system. The default keystore file is JAVA_HOME\jre\lib\security\cacerts. This file contains the list of certificate authorities that the JRE will trust. A list of well-known trusted companies like Verisign is already in the keystore. To see this list, execute with password "changeit":

D:\>keytool -list -rfc -keystore JAVA_HOME\jre\lib\security\cacerts

The keytool application can be used to edit this file. However, just in case something goes wrong it's better to create a new file. If keytool isn't told which file to use it creates HOME/.keystore by default.

To generate your own self-signed certificate execute:

D:\>keytool.exe -genkey -alias Tomcat -keyalg RSA -storepass bigsecret -keypass bigsecret -dname "cn=localhost"

After executing this command there will be a .keystore file in your HOME directory. Here's what the switches mean.

  • genkey: Tells the keytool applica-tion to generate new public/private key pair.
  • alias: The name used to refer to the keys. Remember, the .keystore file can contain many keys.
  • keyalg: Generates public/private keys using the RSA algorithm.
  • storepass: What password is needed to access the .keystore file.
  • keypass: What password is needed to manage the keys.
  • dname: This value is very important. I used "localhost" because this example is designed to run locally. If a Web application is registered as http://www.myserver.com then this value must be www.myserver.com. If the names don't match the certificate will automatically be rejected.
Once the keytool application creates a new public/private key pair it automatically self-signs the key. You have just generated your own self-signed certificate, which can be used for HTTPS communications. You only need to extract the self-signed public key. I'll show how to do this later.

Configuring Tomcat for SSL
Now you have to configure Tomcat to use your self-signed certificate. I used Tomcat 5.0.30. Edit the TOMCAT/conf/server.xml file. Search the file for "8443" and uncomment the <Connector.../> bound to that port. Then you'll have to add the following property to the <Connector.../>:

keystorePass="bigsecret"

When the JRE starts, it will automatically find the HOME/.keystore file and Tomcat will try to access it using the password "bigsecret." When Tomcat starts there should be output to the console that looks similar to:

Feb 4, 2006 3:11:23 PM org.apache.coyote.http11.Http11Protocol start
INFO: Starting Coyote HTTP/1.1 on http-8443

This means the <Connector.../> successfully read the .keystore file and you can now do secure HTTPS connections over the 8443 port. Open a Web browser and try https://localhost:8443/. Because the certificate is self-signed the Web browser will display a dialog box asking about trusting the connection. If accepted, all communications will be secure over HTTPS.

Creating the Web Service
I'm going to use the Apache Axis project to create a very simple Web Service. The Web Service will simulate checking for new e-mail messages. A Web Service client passes a token uniquely identifying a user. The Web Service returns a list of new e-mail messages (see Listing 1).

To get the Web Service deployed, follow these steps:

  1. Cut and paste the code from Listing 1 into a file named Email.jws in Webapp's root directory.
  2. Edit the Web.xml file, adding the Axis servlet and a *.jws mapping (Listing 2).
  3. Put the Axis jar files in WEB-INF/lib. See References at the end of this article for the Axis project URL.
After deploying this article's accompanying WAR file (and configuring Tomcat for SSL), the Web Service is accessible securely over HTTPS at the following URL:

https://localhost:8443/JDJArticleWebService/Email.jws

Using WSDL2Java
The Axis project provides a tool named WSDL2Java that takes a Web Service WSDL and automatically create the Java source code needed to use the Web Service. See Listing 3 for the command line used to generate code for the Email.jws Web Service.

Notice the URL in Listing 3 used to access the WSDL. It's the non-secure HTTP protocol over port 8080. Why not use HTTPS over port 8443? Because of the self-signed certificate, the WSDL2Java tool will encounter the same exact certificate problem this article is trying to provide a solution for. So for now the non-secure protocol must be used. This means the generated code must be altered slightly replacing "http" and "8080" references with "https" and "8443." This article's accompanying client zip file contains the altered code.

Client with a Custom Keystore
The JRE's default keystore is JAVA_HOME\jre\lib\security\cacerts. Java applications will throw an exception whenever they are presented with your self-signed certificate because your certificate isn't in this keystore. Therefore, when developing a client there are two options. The first option is to put your self-signed certificate into the JRE's default keystore. Although this would work it's not a very good solution because customization is required on every client machine. The second option is to generate a custom keystore, put your self-signed certificate into it, and distribute the custom keystore as part of your application (typically inside a jar file).

To create a custom keystore for your client the following has to be done:

  1. Export the self-signed public key from HOME/.keystore.
  2. Import the self-signed public key into a new keystore for you client.
To export the self-signed public key from HOME/.keystore execute the following:

D:\>keytool.exe -export -rfc -alias Tomcat -file Tomcat.cer -storepass bigsecret -keypass bigsecret

Now create the custom keystore for the client by importing Tomcat.cer:

D:>keytool.exe -import -noprompt -trustcacerts -alias Tomcat -file Tomcat.cer -keystore CustomKeystore -storepass littlesecret

Using the switch "-keystore CustomKeystore" will create a new keystore file called "CustomKeystore" in the present working directory. You'll find the CustomKeystore file in the /classpath/resources/keystore directory of this article's client zip file. Replace this one with the file just generated.

Now all that's left to do is to create a client that uses this custom keystore. I'll demonstrate two ways to do this.

The first is to use the Java system properties javax.net.ssl.trustStore and javax.net.ssl.trustStorePassword to point to the CustomKeystore file and provide the password to access it. My example Web Service client in the jdj.wsclient.truststore package takes this approach (see Listing 4). The main() method sets the system properties then creates the objects to use the Web Service. When the JRE needs to access a keystore it looks for the "classpath/resources/keystore/CustomKeystore" file on the file system. Although this is a simple solution it's problematic because the keystore file must be on the file system and the client code must know where to look for it.

The second is a more portable solution that keeps resources inside the jar file and avoids the file system issues. The client code is responsible for reading the CustomKeystore file and somehow using it to create a secure connection to the server. My example Web Service client in the jdj.wsclient.socketfactory package takes this approach (see Listing 5). Listing 5 shows how to read the CustomKeystore file as a resource and use it to create a javax.net.ssl.SSLSocketFactory. Configuring the Axis pluggable architecture, the MySocketFactory class can be then used to create secure Socket objects from this factory.

Conclusion
This article started with a simple problem: I wanted to secure Web Service communications over HTTPS using my own self-signed certificates. By default, the JRE will reject my application's self-signed certificate because I am not a trusted certificate authority. To get secure communications to work I had to get the Web Service client JRE to trust my self-signed certificate. To achieve this, I used the keytool application and generated a new public/private key pair, extracted the self-signed public key, and then created a new keystore and imported this self-signed certificate. I then created a totally self-contained Web Service client that doesn't require any client-side configuration.

References

More Stories By Michael Remijan

Michael J. Remijan is a research programmer at the National Center for Supercomputing Applicaitons (NCSA). His chief responsibilities include data miming and access to terabyte-sized astronomy data sets. Michael received a BS in mathematics and computer science from the University of Illinois and is currently working on an MBA in technology management.

Comments (5) View Comments

Share your thoughts on this story.

Add your comment
You must be signed in to add a comment. Sign-in | Register

In accordance with our Comment Policy, we encourage comments that are on topic, relevant and to-the-point. We will remove comments that include profanity, personal attacks, racial slurs, threats of violence, or other inappropriate material that violates our Terms and Conditions, and will block users who make repeated violations. We ask all readers to expect diversity of opinion and to treat one another with dignity and respect.


Most Recent Comments
Devs 07/26/06 03:20:28 PM EDT

Hello,
I read your article. I am trying to use your approach mentioned in Listing 5(putting keytore on the jar file ). How do I go about doing it. I create MySSLFactory using Listing 5. Now what do I have to confiugre in axis. How do I tell axis to use the MySSLFactory.

Thanks
Deval

Faizan Raza 06/21/06 02:46:05 AM EDT

Nice article and very precise.
Helped me a lot in sorting out the problems i had with the self signed certificate.

thanks
Faizan

Philip Rallings 06/18/06 04:15:00 PM EDT

excellent article that explains everyting clearly

Is it possibe to have a cope of the zip file that accompanied the article.

Many Thanks
Phi

Ismael 06/02/06 07:06:48 AM EDT

I have followed your article, it is very clear, congratulations.

But I am having some problems with my testings, I am trying to use your thid approach (putting keytore on the jar file as you detail on listing 5).

I know that I should use MySocketFactory, but the listing code contains only a method, it is not a class.

What should I do:

-Create a class (which interfaces should it implement o which classes to extend). How should I configure Axis to use it.

-Put this method on a class and call it on the startup (code has a reference to factory not solved on the method)

Maybe I should get the default factory (I do not know which method should I use) and set the new one on the code published.

It would be great to have all the complete code used to make the article. This way I could find out how to apply them to my code.

Regards,
Ismael

SYS-CON Media News Desk 05/26/06 10:44:51 AM EDT

One of the great things about the Java programming language is the Open Source community that provides great applications at little or no cost. An example of this is Apache Tomcat, which provides a solid Web server for development using servlet or JSP technology. Now that Web Service technology is maturing there's a potential for a whole scenario of applications to take advantage of a Swing feature-rich thin client on the front-end coupled to the data verification and business logic already developed in the Web or ejb tier. Such applications are only viable if they can be secure, however, security doesn't have to come at a great cost. The purpose of this article is to demonstrate how Web Service clients can use self-signed security certificates over the secure HTTPS protocol.

@ThingsExpo Stories
20th Cloud Expo, taking place June 6-8, 2017, at the Javits Center in New York City, NY, will feature technical sessions from a rock star conference faculty and the leading industry players in the world. Cloud computing is now being embraced by a majority of enterprises of all sizes. Yesterday's debate about public vs. private has transformed into the reality of hybrid cloud: a recent survey shows that 74% of enterprises have a hybrid cloud strategy.
Internet-of-Things discussions can end up either going down the consumer gadget rabbit hole or focused on the sort of data logging that industrial manufacturers have been doing forever. However, in fact, companies today are already using IoT data both to optimize their operational technology and to improve the experience of customer interactions in novel ways. In his session at @ThingsExpo, Gordon Haff, Red Hat Technology Evangelist, will share examples from a wide range of industries – includin...
WebRTC is the future of browser-to-browser communications, and continues to make inroads into the traditional, difficult, plug-in web communications world. The 6th WebRTC Summit continues our tradition of delivering the latest and greatest presentations within the world of WebRTC. Topics include voice calling, video chat, P2P file sharing, and use cases that have already leveraged the power and convenience of WebRTC.
"We build IoT infrastructure products - when you have to integrate different devices, different systems and cloud you have to build an application to do that but we eliminate the need to build an application. Our products can integrate any device, any system, any cloud regardless of protocol," explained Peter Jung, Chief Product Officer at Pulzze Systems, in this SYS-CON.tv interview at @ThingsExpo, held November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA.
Data is the fuel that drives the machine learning algorithmic engines and ultimately provides the business value. In his session at 20th Cloud Expo, Ed Featherston, director/senior enterprise architect at Collaborative Consulting, will discuss the key considerations around quality, volume, timeliness, and pedigree that must be dealt with in order to properly fuel that engine.
"Once customers get a year into their IoT deployments, they start to realize that they may have been shortsighted in the ways they built out their deployment and the key thing I see a lot of people looking at is - how can I take equipment data, pull it back in an IoT solution and show it in a dashboard," stated Dave McCarthy, Director of Products at Bsquare Corporation, in this SYS-CON.tv interview at @ThingsExpo, held November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA.
IoT is rapidly changing the way enterprises are using data to improve business decision-making. In order to derive business value, organizations must unlock insights from the data gathered and then act on these. In their session at @ThingsExpo, Eric Hoffman, Vice President at EastBanc Technologies, and Peter Shashkin, Head of Development Department at EastBanc Technologies, discussed how one organization leveraged IoT, cloud technology and data analysis to improve customer experiences and effici...
Fact is, enterprises have significant legacy voice infrastructure that’s costly to replace with pure IP solutions. How can we bring this analog infrastructure into our shiny new cloud applications? There are proven methods to bind both legacy voice applications and traditional PSTN audio into cloud-based applications and services at a carrier scale. Some of the most successful implementations leverage WebRTC, WebSockets, SIP and other open source technologies. In his session at @ThingsExpo, Da...
"IoT is going to be a huge industry with a lot of value for end users, for industries, for consumers, for manufacturers. How can we use cloud to effectively manage IoT applications," stated Ian Khan, Innovation & Marketing Manager at Solgeniakhela, in this SYS-CON.tv interview at @ThingsExpo, held November 3-5, 2015, at the Santa Clara Convention Center in Santa Clara, CA.
As data explodes in quantity, importance and from new sources, the need for managing and protecting data residing across physical, virtual, and cloud environments grow with it. Managing data includes protecting it, indexing and classifying it for true, long-term management, compliance and E-Discovery. Commvault can ensure this with a single pane of glass solution – whether in a private cloud, a Service Provider delivered public cloud or a hybrid cloud environment – across the heterogeneous enter...
The cloud promises new levels of agility and cost-savings for Big Data, data warehousing and analytics. But it’s challenging to understand all the options – from IaaS and PaaS to newer services like HaaS (Hadoop as a Service) and BDaaS (Big Data as a Service). In her session at @BigDataExpo at @ThingsExpo, Hannah Smalltree, a director at Cazena, provided an educational overview of emerging “as-a-service” options for Big Data in the cloud. This is critical background for IT and data professionals...
Today we can collect lots and lots of performance data. We build beautiful dashboards and even have fancy query languages to access and transform the data. Still performance data is a secret language only a couple of people understand. The more business becomes digital the more stakeholders are interested in this data including how it relates to business. Some of these people have never used a monitoring tool before. They have a question on their mind like “How is my application doing” but no id...
@GonzalezCarmen has been ranked the Number One Influencer and @ThingsExpo has been named the Number One Brand in the “M2M 2016: Top 100 Influencers and Brands” by Onalytica. Onalytica analyzed tweets over the last 6 months mentioning the keywords M2M OR “Machine to Machine.” They then identified the top 100 most influential brands and individuals leading the discussion on Twitter.
What happens when the different parts of a vehicle become smarter than the vehicle itself? As we move toward the era of smart everything, hundreds of entities in a vehicle that communicate with each other, the vehicle and external systems create a need for identity orchestration so that all entities work as a conglomerate. Much like an orchestra without a conductor, without the ability to secure, control, and connect the link between a vehicle’s head unit, devices, and systems and to manage the ...
More and more brands have jumped on the IoT bandwagon. We have an excess of wearables – activity trackers, smartwatches, smart glasses and sneakers, and more that track seemingly endless datapoints. However, most consumers have no idea what “IoT” means. Creating more wearables that track data shouldn't be the aim of brands; delivering meaningful, tangible relevance to their users should be. We're in a period in which the IoT pendulum is still swinging. Initially, it swung toward "smart for smar...
In an era of historic innovation fueled by unprecedented access to data and technology, the low cost and risk of entering new markets has leveled the playing field for business. Today, any ambitious innovator can easily introduce a new application or product that can reinvent business models and transform the client experience. In their Day 2 Keynote at 19th Cloud Expo, Mercer Rowe, IBM Vice President of Strategic Alliances, and Raejeanne Skillern, Intel Vice President of Data Center Group and G...
Information technology is an industry that has always experienced change, and the dramatic change sweeping across the industry today could not be truthfully described as the first time we've seen such widespread change impacting customer investments. However, the rate of the change, and the potential outcomes from today's digital transformation has the distinct potential to separate the industry into two camps: Organizations that see the change coming, embrace it, and successful leverage it; and...
With major technology companies and startups seriously embracing IoT strategies, now is the perfect time to attend @ThingsExpo 2016 in New York. Learn what is going on, contribute to the discussions, and ensure that your enterprise is as "IoT-Ready" as it can be! Internet of @ThingsExpo, taking place June 6-8, 2017, at the Javits Center in New York City, New York, is co-located with 20th Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry p...
20th Cloud Expo, taking place June 6-8, 2017, at the Javits Center in New York City, NY, will feature technical sessions from a rock star conference faculty and the leading industry players in the world. Cloud computing is now being embraced by a majority of enterprises of all sizes. Yesterday's debate about public vs. private has transformed into the reality of hybrid cloud: a recent survey shows that 74% of enterprises have a hybrid cloud strategy.
Internet of @ThingsExpo, taking place June 6-8, 2017 at the Javits Center in New York City, New York, is co-located with the 20th International Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world. @ThingsExpo New York Call for Papers is now open.