fortitool: one Go binary decrypts FortiOS firmware end to end — key nobody had
A researcher built fortitool, a single dependency-free Go binary that runs the whole FortiOS decryption pipeline — outer XOR cipher, inner rootfs scheme, filesystem extraction, and config-secret decryption — auto-picking the right method by version. Previous tooling only solved one slice each. The writeup also documents a previously undisclosed key and shows how Fortinet reuses a small key pool across product lines.