Since the 0.5.0 version, KFileCoder allows you to choose an algorithm when you create a new KFC archive:
In this version, two algorithms are supported: PC1 (default) and IDEA. PC1 was written by Alexandre Pukall. XOR, which was used until the 0.3.x versions is no longer supported: in deed, it provides a really low security for data, and PC1 is really better. IDEA is another 128 bits hard encryption algorithm.
PC1 was made by Mister Alexander. This algorithm keeps the data file size: encoded data uses the same size as decoded data. The PC1 algorithm is implemented in algo-pc1.cpp and algo-pc1.h. It is used as a data encryption algorithm, and in many common operations of the program.