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There is a variety of utilities to do this, in various languages (albeit; they are mostly shell/scripting languages)
I cannot post the links to all of them, because I am a new stackoverflow user - I can only post 1 link, so I created a page which lists them all - including the one C one I speak about below - http://curetheitch.com/projects/buildcrx/6/
Anyway, I spent a few hours and put together a version in C which runs on Windows or Linux, as the other solutions require installation of a scripting language or shell (i.e. python, ruby, bash, etc.) and OpenSSL. The utility I wrote has OpenSSL statically linked so there are no interpreter or library requirements.
The repository is hosted on github, but the link above has a list of my utility and other peoples solutions.
Nothing listed for Java, which was your preference, but hopefully that helps!