I have a limited understanding of encryption of data. I know that servers and clients can encrypt and decrypt information through a variety of methods. I also know that security through obscurity is not a good idea and that there are very reliable open-source encryption options.
That said, I've been told (or read somewhere) that the type of encryption used is non-reversible. i.e. you can't decrypt something by knowing the algorithm. This is the bit that I can't grasp. How can an algorithm not be reverse engineerable? Why are open source encryption options considered more secure than proprietary equivalents?