By 1nfocalypse
Feisty is a toy implementation of a Feistel Network. I previously released a bugged version, which has now been fixed. Feisty is also now equipped with the ability to utilize 256 bit keys. Feistel Networks are still feasibly secure, however, serious usage is discouraged due to theoretical attacks being possible. For more information on Feistel Networks and other cryptographic schemes, please be sure to check out my writeup on mathematical cryptography, which can be found here.
If you would like to submit a PR, please feel free to do so. There are very likely some bugs hiding in here that I didn't sniff out. If you choose to submit a PR, please explain your changes and I'll be happy to review it. Thank you!
Feistel Networks are outdated, and this is largely an educational toy. While it has the capacity to encrypt and decrypt messages, it is not meant for serious use. Please consider alternative cryptosystems, such as AES, for contemporary needs. By using this software, you acknowledge that neither I nor any contributors are responsible for any losses or damage that may occur. For more information, please consult the license, which can be found here.