How to add or list certificates from keystore or trustStore in Java - Keytool Example

How to add certificates on keystore in Java is primary questions when you start working on SSL connection and simple answer is keytool utility in Java is used to add or list Certificates into keystore. SSL is the industry standard for secure communication between two parties e.g. client and server. SSL offers two benefits, it encrypts data transferred between client and server to make it hard for someone to access and understand in between and SSL also verify the identity of two parties in communication and certificates are used for that purpose. SSL Setup in Java comes during various process e.g. Setting up SSL on tomcat, configuring messaging over SSL or JDBC over SSL are some examples of task where you need to deal with keyStore, certificates, and trustStores.


For those who are not aware of what is a keystore in Java and what is certificates, we will see the brief introduction in next section, but for more detailed discussion you refer my next post how SSL, HTTPS, and Certificates work together in Java application.

Basics of SSL Certificates and Keystore in Java

When we access a secure site which uses SSL for providing identity and encryption, it provides a certificate which was verified by a trusted third party sites like Verisign, GoDaddy or hThwate. by using certificates browser or java clients knows that they talking to the correct site (who it claims to be) and not on redirected proxy site. this step is pretty transparent if you access websites using browser because if certificate is not on browser's trusted store it will ask you to add that certificate and it will be subsequently added, But when you access a secure site using Java program, this step of certificate hand shaking is not transparent to user and certificates are verified from JRE's trustStore. This trustStore is located on JDK Installation directory referred by JAVA_HOME  e.g. JAVA_HOME/jre/lib/security and commonly named as "cacerts".

If certificate provided by the secure site is present on JRE's trustStore SSL connection would be established but if the certificate is not there than Java will throw an exception and to solve that you need to add that certificate into trustStore.

Terms like keyStore and trustStore are often used interchangeably and the same file can act as keystore as well as trustStore it just matter of pointing javax.net.ssl.keyStore and javax.net.ssl.trustStore properties to that file but there is a slight difference between keystore and trustStore.

A keyStore is used to store individual identity or certificate while trustStore is used to store other parties certificates signed by CA. See difference between keystore and trustStore, for more differences.

How to add, remove and list certificates from Java keystore

In this article, we will see how to add ,remove and list certificates from Java keystore using keytool utility.

keytool is binary located inside JAVA_HOME/jre/lib/security folder and used for adding, removing and listing

certificates. here is step by step example of adding certificates in Java:

Example of listing certificates from Java Keystore:

Before adding new certificates in keystore or trust store its good to see, count and verify already installed certificates. run following keytool command to get a list of certificates from keystore:

javin@localhost:C/Program Files/Java/jdk1.6.0_26/jre/lib/security keytool -list -keystore cacerts Enter keystore password:  changeit Keystore type: JKS Keystore provider: SUN Your keystore contains 76 entries digicertassuredidrootca, 07/01/2008, trustedCertEntry, Certificate fingerprint (MD5): 87:CE:0B:7B:2A:0E:49:00:E1:58:71:9B:37:A8:93:72 trustcenterclass2caii, 07/01/2008, trustedCertEntry, Certificate fingerprint (MD5): CE:78:33:5C:59:78:01:6E:18:EA:B9:36:A0:B9:2E:23

You see currently keystore "cacerts" holds 76 certificates. You can also see Core Java for Impatient to learn more usages of keytool and other JDK command line tools.

Example of adding Certificate on Java KeyStore:

Now let's see example of adding certificates into key store in Java:

1. Get Certificate: easier way is to point your browser to that URL and when certificate is presented save it on your

local folder or directory say in C:/certificates/test.cer

2. Now go to Security folder of your JRE installation directory. id you have JDK installed then it would be

something like C:/Program Files/Java//jdk1.6.0_20/jre/lib/security

3 Execute following keytool command to insert certificate into keystore

keytool -import -keystore cacerts -file test.cer

Now this will print details about certificate and ask you for confirmation of adding certificates:

Trust this certificate? [no]:  y

Certificate was added to keystore

if you approve it by typing "y" certificate will be added into keystore.

Trust this certificate? [no]:  n

Certificate was not added to keystore

if you decline it by typing "n" certificate will not be added into keystore.

if you cannot access secure URL using the browser then you can use InstallCert by which you can add certificate into keystore by the program. For detailed example see the last section of LDAP authentication with SSL in Java and Spring security. I have provided detailed steps to use InstallCert.java tool.

Important point about SSL, KeyStore and keyTool in Java

1. Certificates are required to access secure sites using SSL protocol or making a secure connection from the client to the server.

2. JRE stores certificates inside keystore named as "cacerts" in folder C:/Program Files/Java//jdk1.6.0_20/jre/lib/security.

3. Common password of keystore is "Changeit".

4. Keytool is used to access keystore in Java and by using keytool you can list, add certificates from keystore.

5. If you are implementing SSL connection on Server side say Tomcat you need both keyStore and trustStore, both can be the same file, though. keyStore will be used to store server certificate which server will present to the client on SSL connection.

That’s all on how to add and list certificates from keyStore or trustStore in java. The keytool utility which comes with JDK installation will help you to create alias, list certificates etc.

Further Reading
Understanding the Java Virtual Machine: Security
Learn Spring Security by Eugen
Java Performance The Definitive Guide

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