Resonance_Lock_The_Harmonic_Multiplier

Goal Phase-lock UART baud-rate oscillator to exactly 2,345,679 baud, exercise the 512-bit hardware multiplier, extract the fixed flag token before the 45 s supercapacitor drains.

Connection

Protocol (8N1 framing)

Enter CALIBRATE Send single byte 0xCA (no reply).

Calibration burst (repeat until LOCKED) Send exactly 64× 0x55 bytes with precise baud timing. Server replies: ERR:+00123 / ERR:-00045 (PPM error) Target: |error| ≤ 1,000 PPM for 5 consecutive good bursts → LOCKED

Locked mode (45 s window) Send: 0xAA + 64-byte A + 64-byte B (512-bit big-endian operands) Receive: FLAG:apoorv{...} (flag is fixed; any valid A/B works)

Critical Warnings

HSM tamper fuse is one-time and permanent per TCP session. Never send: JTAG/SWD, flash reads, garbage bytes, or wrong patterns → ERR:HSM_TAMPER_FUSE_BLOWN (all future flags garbage). Use TCP_NODELAY, send byte-by-byte. Server times the last 63 bytes (first byte is trigger only). Solver tips

Inter-byte delay = 10 / 2_345_679 s ≈ 4.263 µs. Use busy-wait loop with time.perf_counter_ns() (sleep is too coarse). No math needed — flag is constant once lock succeeds. Errors you’ll see ERR:PROTO, ERR:TIMEOUT, ERR:PATTERN, ERR:PAYLOAD, TIMEOUT:SUPERCAP_DRAINED

Disconnect/reconnect for a fresh chip if fuse blows. Good luck!

Author: b4bU-n@mBo0tHiR!