The best practice for any code base which runs on a user's computer is to publish it. This builds trust and encourages the creation of derivative works and improvements.
You can find the complete client source in .zip format in the Client Files file gallery (see "Files" link in the top menu above). These archives have been signed using the private key of the project developers. You can obtain the javadocs for the Silent-Vault client here.
For detailed instructions on how to build this source into a working client yourself, see this page.
Special temporary note: the source code in the archive is for the SVSpark 2.7.0 revision, which was released in August, 2014. The current release is 2.7.1, released in August, 2015. The source archives have not yet been updated to reflect the new release. The update will be performed in the near future.
Sources for the Voucher-Safe client, the Spark jabber plugin client, and the command line client (CLI) can be downloaded from the Voucher-Safe dev site. (Note that you'll need to register a login there in order to access the file galleries.) Although source for the Voucher-Safe server plugins is not yet published, you can download the API javadocs for them.