XLD Logchecker

This is a fork of https://github.com/puddly/xld_logsigner, to be used within our downstream applications, removing unnecessary functionality that we do not need.

Based heavily on barrybingo/xld_sign. This is a complete disassembly of the XLD log signing algorithm, re-implemented in Python 3.5+.

Usage

usage: xld.py [-h] (--verify | --sign) FILE

Verifies and resigns XLD logs

positional arguments:
  FILE        path to the log file

optional arguments:
  -h, --help  show this help message and exit
  --verify    verify a log
  --sign      sign or fix an existing log

Overview

The final code isn't pretty, but it is simple enough to describe the algorithm.

1. The log is encoded as UTF-8 and hashed with a SHA-256 variant that uses a different IV.
2. The digest is converted to hex and the string \nVersion=0001 is appended onto the end.
3. The versioned hex-digest is then passed through an unidentified scrambling function that operates on pairs of bytes (open an issue if you recognize it).
4. The resulting bytestring is then encoded using a 65-character lookup table with a strange mapping.