Solving the Jane Street Reverse Engineering Challenge

The Jane Street Reverse Engineering Challenge required taking an Application-Specific Integrated Circuit (ASIC) and determining its functionality. An ASIC is a custom-designed computer chip manufactured for specific purposes, often providing improved performance over standard manufacturer equipment. The challenge involved working with a GDS file that describes the chip's design, but the specific meaning of 'GDS' was unclear.

The participants were given two parts: a warmup with comprehensive design details and the actual puzzle with limited information.

To approach the challenge, the reporter initially tried various methods, including poking around the files, researching unfamiliar terms, and employing a Python library called 'gdstk' to read the GDS files. This library allowed them to identify 27 elements within the warmup puzzle. The reporter also encountered a 'vcd' file, a type of simulation output file, which contained ASCII characters that hinted at hidden messages within the circuit.

The reporter built their own circuit simulator using SQLite3 and a custom language parser, eventually creating a harness for scripting inputs and validating outputs. A wave form viewer was briefly considered, but a GDS viewer built with Raylib proved more practical for annotating the circuit and extracting the Jane Street logo. The reporter discovered that the library could export elements as SVG files, which provided valuable design element descriptions and helped map specific geometry to the circuit's inputs and outputs. This documentation proved crucial in ultimately solving the challenge.