What has this got to do with Linux? C and Java are platform independent, so that means it can run on pretty much any platform that has available compilers, so this means that this is not really a question appropriate for this forum (Unless of course you are planning on using a library for the encryption/decryption that only runs on Linux, etc). A better place would be in the Java and C forums.
Programming is 10% science, 20% ingenuity, and 70% getting the ingenuity to work with the science. WYSIWYMGIYRRLAAGW: What You See Is What You Might Get If You’re Really Really Lucky And All Goes Well.