do you have visual basic???? visual c++???? any compiler?? Go to pscode.com and search for encryption. I made an encryptor myself using XOR functions a while ago in VB, but i dont know where it is. There are many algorithms you can use to make and encryptor, its just a matter of what you need it for. There are some(which i like) that use random encryption with a seed value, so you can set a password for the file, so that even if someone has a decryptor, they would have to go through every seed and look at the file to see if it did any good. Umm.....so to answer your question....im not sure what you mean by "what file types are used for encoding text".
It's Dr. Know, Not Darknow