A simple file command line utility for file encryption using the ISAAC cryptographic pseudo-random number generator. The implementation of the random number generator is not mine, but the method of seeding the state from a passphrase and the feedforward cipher element are both mine.
$ gcc -o ic ic.c
$ ic <commandflags> passphrase input-file output-file
e encrypt the input-file, write result to output-file
d decrypt the input-file, write result to output-file