A custom encrypted CPU reverse-engineering challenge, solved by GPT-6 in under 30 minutes

HellGates, custom CPU gate-level challenge

The author built a custom 32-bit encrypted CPU in VHDL with multiple obfuscation layers, anti-tamper, and anti-debug. It sat unsolved for a year—humans gave up after weeks, and Claude, ChatGPT, and DeepSeek all failed. In September 2026, GPT-6 solved it in 20–30 minutes on SRE-Bench. The weak point was lazy crypto on the CPU state; GPT-6 used a side-channel/differential analysis to strip obfuscation, run the netlist, and decrypt 1GB of memory. The post details the CPU architecture, instruction set, aligned memory design, and toolchain, with the author now second-guessing whether a microcode engine would have been overkill.

Why it matters: GPT-6 solved a hardware reverse-engineering challenge on SRE-Bench in 20-30 minutes that humans and all prior models failed at for a year, backed by concrete technical details and a third-party benchmark. Downside: this is a personal blog post, not an official release, and the...