EAC Logchecker

This is a transparent implementation of the Exact Audio Copy log checksum algorithm in Python 3.5+.

This is a fork of https://github.com/puddly/eac_logsigner, with modifications to have it better match the output of the actual EAC Logchecker to be used in downstream applications. All credit goes to puddly for reverse-engineering the closed source EAC to develop the base.

Requirements

• Python 3.5+
• pprp==0.2.6

Installation

From PyPI:

$ pip install eac-logchecker

From source:

$ git clone https://github.com/OPSnet/eac_logchecker.py
$ cd eac_logchecker.py
$ python setup.py install

Usage

usage: eac_logchecker.py [-h] [--json] file

Verifies and resigns EAC logs

positional arguments:
file        input log file

optional arguments:
-h, --help  show this help message and exit
--json      Output as JSON

Example

$ eac_logchecker logs/01.log
Log Integrity Checker   (C) 2010 by Andre Wiethoff

1. Log entry is fine!
$ eac_logchecker logs/01.log
$ eac_logchecker logs/05.log
Log Integrity Checker   (C) 2010 by Andre Wiethoff

1. Log entry is fine!
2. Log entry is fine!
$ eac_logchecker --json logs/05.log
[{"message": "Log entry is fine!", "status": "OK"}, {"message": "Log entry is fine!", "status": "OK"}]

Algorithm

1. Strip the log file of newlines and BOMs.
2. Cut off the existing signature block and (re-)encode the log text back into little-endian UTF-16
3. Encrypt the log file with Rijndael-256:
   • in CBC mode
   • with a 256-bit block size (most AES implementations hard-code a 128-bit block size)
   • all-zeroes IV
   • zero-padding
   • the hex key 9378716cf13e4265ae55338e940b376184da389e50647726b35f6f341ee3efd9
4. XOR together all of the resulting 256-bit ciphertext blocks. You can do it byte-by-byte, it doesn't matter in the end.
5. Output the little-endian representation of the above number, in uppercase hex.