KaraZajac
754af4134a
Brings KAT to 32 protocol decoders. Ported from the ProtoPirate reference and the D4C1-Labs/Flipper-ARF firmware: ProtoPirate (8): Kia V7, Ford V1, Ford V2, Ford V3, Chrysler V0, Honda Static, Honda V1, Land Rover V0. Flipper-ARF (6): Toyota, Land Rover RKE, Mazda Siemens, BMW CAS4, Porsche Cayenne, PSA2. Each decoder is gated (CRC / checksum / fixed markers / frame structure) so it cannot false-match existing protocols; every previously-decoding IMPORTS capture decodes unchanged. Real-capture decodes added for Ford V3 (LDV T80), Honda Static (Honda), Toyota (Camry NRZ variant), and PSA2 (Groupe PSA, serial 0x99EB25); the rest are validated by encode/decode round-trip and synthetic-frame tests. Also fixes a debug-only underflow panic in keeloq_common::keeloq_decrypt (15 - r underflowed; now wrapping_sub to match the reference's unsigned wrap; release behavior unchanged). Adds per-protocol docs, updates the README protocol table, capture metadata (encoding / RF / encryption), make-suggestion mapping, and CHANGELOG. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01JEfaKqzB3T4qsrybwfEi73
70 lines
3.1 KiB
Markdown
70 lines
3.1 KiB
Markdown
---
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layout: default
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---
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# Land Rover V0 Protocol
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**Rust module:** `src/protocols/land_rover_v0.rs`
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**Reference:** `REFERENCES/ProtoPirate/protocols/land_rover_v0.c`
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## Overview
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Land Rover V0 uses **differential** Manchester (NOT the Flipper transition table) at 250/500 µs, with a
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~750 µs sync pulse and a ≥64-pair short preamble. The frame is 81 bits = an 80-bit body (`raw[0..10]`)
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plus one trailing `extra_bit`. The 64-bit key reported as `data` is `raw[0..8]` big-endian; `raw[8..10]`
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is a 16-bit `tail`.
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The check is a proprietary 3-bit polynomial over the counter (`calculate_check`); the tail is `0xFFFF`
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or `0x7FFF` depending on a 1-bit parity of the counter (`calculate_tail`). Emission is gated on the
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reserved bits being zero, the check matching, the tail matching, and `extra_bit` set — so Land Rover V0
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is strongly validated and will not false-match.
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## Timing
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| Parameter | Value | Notes |
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|-------------|--------|------------------------|
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| Short | 250 µs | ±100 µs (te_delta) |
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| Long | 500 µs | ±100 µs |
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| Sync | 750 µs | ±120 µs |
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| Min bits | 81 | 80-bit body + extra_bit|
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| Preamble | ≥64 pairs | |
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## Frame Layout (81 bits)
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64-bit key (`raw[0..8]`):
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- **bytes 0–2:** 24-bit command signature — Lock = `0xC20363`, Unlock = `0xA285E3`
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- **bytes 3–5:** 24-bit serial
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- **byte 6 + byte 7 MSB:** 9-bit counter = `(b6 << 1) | (b7 >> 7)`
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- **byte 7 bits 0x78:** 3 reserved bits (must be 0)
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- **byte 7 bits 0x07:** 3-bit check (`calculate_check`)
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Then `raw[8..10]` = 16-bit tail (`0xFFFF`/`0x7FFF`), and a trailing `extra_bit` (must be 1). The tail is
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stashed in `extra` for the encoder.
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## RF
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- **Encoding:** differential Manchester
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- **RF modulation:** FM
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- **Encryption:** none — gated on the 3-bit check polynomial + tail parity + reserved-bits + extra_bit
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- **Frequencies:** 315 MHz, 433.92 MHz
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## Decoder Steps
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1. **Reset → PreambleLow/PreambleHigh** — count short pairs (≥64), terminated by a ~750 µs sync HIGH.
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2. **SyncLow** — a ~750 µs sync LOW seeds the frame (bit 0 = 1) and enters Data.
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3. **Data** — the differential machine (`process_transition`/`add_decoded_bit`) tracks `previous_bit`, skips the initial boundary short-high pad, and completes short half-bits via `pending_short`. At 81 bits, `finish_frame` validates and emits.
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## Encoder
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Supported. Builds the 64-bit key from signature/serial/counter, emits a 319-pair preamble, the sync,
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differential-Manchester body, the 16-bit tail, and a trailing extra bit. Faithful-port note: the
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reference encoder forces frame bit 1 = 0, so the Lock signature `0xC20363` (whose bit 1 is 1) is emitted
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as `0x820363`; the Unlock signature `0xA285E3` round-trips cleanly. KAT reproduces this behaviour.
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## Validation
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Verified by an encode→decode round-trip / synthetic-frame check (no local capture available). Unit tests
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cover the check polynomial vs. the reference, the tail parity, Unlock round trips across 256 serial/counter
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values, the Lock forced-bit quirk, and rejection of a corrupted check.
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