Working with Digital Certificates (The Java EE 6 Tutorial)

The Java EE 6 Tutorial

Working with Digital Certificates

Digital certificates for the GlassFish Server have already been generated and can be found in the directory as-install/domain-dir/config/. These digital certificates are self-signed and are intended for use in a development environment; they are not intended for production purposes. For production purposes, generate your own certificates and have them signed by a CA.

To use SSL, an application or web server must have an associated certificate for each external interface, or IP address, that accepts secure connections. The theory behind this design is that a server should provide some kind of reasonable assurance that its owner is who you think it is, particularly before receiving any sensitive information. It may be useful to think of a certificate as a “digital driver’s license” for an Internet address. The certificate states with which company the site is associated, along with some basic contact information about the site owner or administrator.

The digital certificate is cryptographically signed by its owner and is difficult for anyone else to forge. For sites involved in e-commerce or in any other business transaction in which authentication of identity is important, a certificate can be purchased from a well-known CA such as VeriSign or Thawte. If your server certificate is self-signed, you must install it in the GlassFish Server keystore file (keystore.jks). If your client certificate is self-signed, you should install it in the GlassFish Server truststore file (cacerts.jks).

Sometimes, authentication is not really a concern. For example, an administrator might simply want to ensure that data being transmitted and received by the server is private and cannot be snooped by anyone eavesdropping on the connection. In such cases, you can save the time and expense involved in obtaining a CA certificate and simply use a self-signed certificate.

SSL uses public-key cryptography, which is based on key pairs. Key pairs contain one public key and one private key. Data encrypted with one key can be decrypted only with the other key of the pair. This property is fundamental to establishing trust and privacy in transactions. For example, using SSL, the server computes a value and encrypts it by using its private key. The encrypted value is called a digital signature. The client decrypts the encrypted value by using the server’s public key and compares the value to its own computed value. If the two values match, the client can trust that the signature is authentic, because only the private key could have been used to produce such a signature.

Digital certificates are used with HTTPS to authenticate web clients. The HTTPS service of most web servers will not run unless a digital certificate has been installed. Use the procedure outlined in the next section, Creating a Server Certificate, to set up a digital certificate that can be used by your application or web server to enable SSL.

One tool that can be used to set up a digital certificate is keytool, a key and certificate management utility that ships with the JDK. This tool enables users to administer their own public/private key pairs and associated certificates for use in self-authentication, whereby the user authenticates himself or herself to other users or services, or data integrity and authentication services, using digital signatures. The tool also allows users to cache the public keys, in the form of certificates, of their communicating peers. For a better understanding of keytool and public-key cryptography, see the keytool documentation at http://download.oracle.com/javase/6/docs/technotes/tools/solaris/keytool.html.

Creating a Server Certificate

A server certificate has already been created for the GlassFish Server and can be found in the domain-dir/config/ directory. The server certificate is in keystore.jks. The cacerts.jks file contains all the trusted certificates, including client certificates.

If necessary, you can use keytool to generate certificates. The keytool utility stores the keys and certificates in a file termed a keystore, a repository of certificates used for identifying a client or a server. Typically, a keystore is a file that contains one client’s or one server’s identity. The keystore protects private keys by using a password.

If you don’t specify a directory when specifying the keystore file name, the keystores are created in the directory from which the keytool command is run. This can be the directory where the application resides, or it can be a directory common to many applications.

The general steps for creating a server certificate are as follows.

Create the keystore.
Export the certificate from the keystore.
Sign the certificate.
Import the certificate into a truststore: a repository of certificates used for verifying the certificates. A truststore typically contains more than one certificate.

To Use keytool to Create a Server Certificate provides specific information on using the keytool utility to perform these steps.

To Use `keytool` to Create a Server Certificate

Run keytool to generate a new key pair in the default development keystore file, keystore.jks. This example uses the alias server-alias to generate a new public/private key pair and wrap the public key into a self-signed certificate inside keystore.jks. The key pair is generated by using an algorithm of type RSA, with a default password of changeit. For more information and other examples of creating and managing keystore files, read the keytool online help at http://download.oracle.com/javase/6/docs/technotes/tools/solaris/keytool.html.

Note –

RSA is public-key encryption technology developed by RSA Data Security, Inc.

From the directory in which you want to create the key pair, run keytool as shown in the following steps.

Generate the server certificate.

Type the keytool command all on one line:
java-home/bin/keytool -genkey -alias server-alias -keyalg RSA -keypass changeit -storepass changeit -keystore keystore.jks
When you press Enter, keytool prompts you to enter the server name, organizational unit, organization, locality, state, and country code.

You must type the server name in response to keytool’s first prompt, in which it asks for first and last names. For testing purposes, this can be localhost.

When you run the example applications, the host (server name) specified in the keystore must match the host identified in the javaee.server.name property specified in the file tut-install/examples/bp-project/build.properties.

Export the generated server certificate in keystore.jks into the file server.cer.

Type the keytool command all on one line:
java-home/bin/keytool -export -alias server-alias -storepass changeit -file server.cer -keystore keystore.jks

If you want to have the certificate signed by a CA, read the example at http://download.oracle.com/javase/6/docs/technotes/tools/solaris/keytool.html.

To add the server certificate to the truststore file, cacerts.jks, run keytool from the directory where you created the keystore and server certificate.

Use the following parameters:

java-home/bin/keytool -import -v -trustcacerts -alias server-alias
-file server.cer -keystore cacerts.jks -keypass changeit -storepass changeit

Information on the certificate, such as that shown next, will appear:

Owner: CN=localhost, OU=Sun Micro, O=Docs, L=Santa Clara, ST=CA, 
C=USIssuer: CN=localhost, OU=Sun Micro, O=Docs, L=Santa Clara, ST=CA, 
C=USSerial number: 3e932169Valid from: Tue Apr 08Certificate 
fingerprints:MD5: 52:9F:49:68:ED:78:6F:39:87:F3:98:B3:6A:6B:0F:90 SHA1: 
EE:2E:2A:A6:9E:03:9A:3A:1C:17:4A:28:5E:97:20:78:3F:
Trust this certificate? [no]:

Type yes, then press the Enter or Return key.

The following information appears:
Certificate was added to keystore[Saving cacerts.jks]