This is an implementation of CipherSaber-2 in Purebasic.
It compiles on Linux and Mac OS X. libbsd is recommended on Linux to use readpassphrase(), but getpass() is also available. Please note that getpass() is limited to 128 bytes.
Purebasic is a commercial BASIC, able to generate small and efficient executables on Linux, Mac OS X and Windows. It is not open source -- except the deprecated Amiga variant -- but build by a small team of enthusiastic programmers. The demo version compiles around 800 lines, enough to generate an executable from this source code.
From the CipherSaber FAQ:
CipherSaber is an ultra-simple encryption method. Anyone with a little programming skill can write a CipherSaber program in as few as 16 lines of Basic. You can find out how at: http://ciphersaber.gurus.org
Both, actually. The point is that encryption technology is too simple to be suppressed.