How to use PEM file to create a SSL socket in Java?

Question

See related question.

I have a PEM file provided to me and was told that it will be needed in establishing a SSL socket that connects to a c++ server for some API calls. Does anyone know how I can read in the PEM file and connect? I was also given the parapharse password.

Answer 1

It sounds like the PEM file is a client cert for you to use to login to the server. If it is the client cert, and it sounds like it is, you will likely need a ca cert file also to use in validating the servers certificate in order to establish a connection.

The CA certs need to go into a truststore and your client certs need to go into a keystore. In Java, both of these will be JKS (although it has limited support for PKCS12.) There are default keystore/truststore locations for the JRE as well as for each user. You can also specify external locations for these files in your code, as in the examples below. The commons-ssl library seems to be able to support PEM directly, without the need for JKS, but I haven't used it.

The default passphrase for these keystores in Java is "changeit" without the quotes.

This page shows you have to read the PEM into your keystore/truststore. Here is another example.

Once you have your truststore and keystore set up properly, you need to pass the following JSSE system properties to your JVM:

javax.net.ssl.keyStore
javax.net.ssl.keyStoreType
javax.net.ssl.keyStorePassword
javax.net.ssl.trustStore
javax.net.ssl.trustStoreType
javax.net.ssl.trustStorePassword

You may specify them as -D parameters to the JRE or, as in the examples below, programatically.

Once you finish that, heres a commons-ssl example of creating a socket. Also, heres the Java api for SSLSocket. Heres also an example that doesn't use any apache commons.

Answer 2

You need a library that handles SSL. As John Ellinwood noted, some frameworks (such as Java 2 SE) offers these built-in, for others you'd need to use 3rd party libraries.

C developers often use openssl directly, but it can't be said to be easy and when using C++ there are several "gotchas" that are easy to fall into.

I suggest you use a C++ network library with support for SSL, such as QT's network library, or Poco NetSSL. See here for some tutorial documentation and here for the API documentation - you probably want to take a look at initializeClient which takes a PEM file directly.