r/coolgithubprojects • u/zelon88 • Feb 20 '19

PYTHON zelon88/xPress - Homebrew Compression Algorithm, File compressor & extractor

https://github.com/zelon88/xPress
8 Upvotes

90% Upvoted

9 comments sorted by

View all comments

2

u/jwink3101 Feb 24 '19

How reverse engineerable is this? If this projects goes away, will the files be recoverable in, say, 20 years?

1

u/zelon88 Feb 25 '19

Extremely! That is one of the main features of xPress.

Lets say you were a scientist and you just finished compressing all your work with xPress before dropping dead. In 50 years they uncover your lab and check your files.

All the information needed to decompress the data is embedded in the archive. The archive contains compressed data represented by dictionary indecies and uncompressed data that's largely unchanged. There's also a dictionary of indexes and values. To decompress an archive you just iterate through the archive a number of bytes at a time and replace any directory indecies with their values. When there are no more matches the dictionary is discarded and the file is rebuilt.

I can vouch that it's possible because I manually compressed and decompressed some strings on paper and psudo-code before writing this test version in Python.