this is for the jruby-openssl-0.9.5.gem (and newer). the gem allows Bouncy-Castle version 1.47,1.48,1.49,1.50 and comes with 1.47 embedded inside the gem. in case you want to use another version of the Bouncy Castle jars then JBundler offers a way to do so. create a Jarfile like this

BC_VERSION = '1.50'
jar 'org.bouncycastle:bcpkix-jdk15on', BC_VERSION
jar 'org.bouncycastle:bcprov-jdk15on', BC_VERSION

add to your Gemfile

gem 'jbundler', '~> 0.6'

update your installed gems + jars

$ jbundle install

and now you can verify that you are using

$ bundle exec ruby -rjbundler -e "p Java::OrgBouncycastleJceProvider::BouncyCastleProvider.new.info"

or with your application. just make sure you use require 'jbundler' as early as possible (bundler's auto require feature should(?) take care of this)