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
71 lines
3.2 KiB
Markdown
71 lines
3.2 KiB
Markdown
---
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layout: default
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---
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# Mazda Siemens Protocol
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**Rust module:** `src/protocols/mazda_siemens.rs`
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**Reference:** `Flipper-ARF lib/subghz/protocols/mazda_siemens.c`
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## Overview
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The Siemens/VDO keyfob cipher used on some Mazda vehicles — a DIFFERENT protocol from KAT's existing
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"Mazda V0" (Pandora) decoder, even though both ride a 250/500 µs pair-based stream at 433.92 MHz FM. The
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decoder is pair-based: `feed()` ignores `level` and interprets raw durations in pairs (`process_pair`),
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collecting bits with *inverted* polarity (`state_bit == 0` → stored 1). 64-bit frame.
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Siemens obfuscation (`mazda_xor_deobfuscate`): parity-dependent XOR mask, then bit-deinterleave of bytes
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5/6. The inner Siemens cipher's plaintext is left as-is (no key); only this obfuscation/interleave layer
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is reversed. The gate is an additive checksum `sum(data[0..7]) == data[7]`, plus the structural
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preamble/sync/bit-count constraints, which keeps it from false-matching other 250/500 µs Manchester
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protocols.
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> **Note:** KAT's existing "Mazda V0" decoder implements the same algorithm and keeps first-match
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> priority, so on a shared frame Mazda V0 fires first.
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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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| Min bits | 64 | |
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| Preamble | ≥13 short/short pairs | |
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| Completion | 80–105 collected bits | |
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## Frame Layout (64 bits / 8 bytes, after deobfuscation)
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The 14-byte buffer's leading sync byte is discarded, leaving 8 bytes:
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- **serial:** `data >> 32` (32-bit)
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- **button:** `(data >> 24) & 0xFF` — Lock=0x10, Unlock=0x20, Trunk=0x40
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- **counter:** `(data >> 8) & 0xFFFF` (16-bit)
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- **byte 7:** additive checksum of bytes 0–6
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## RF
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- **Encoding:** pair-based Manchester (inverted polarity), 250/500 µs
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- **RF modulation:** FM
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- **Encryption:** Siemens obfuscation (parity XOR + bit-interleave); gated on the additive checksum
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- **Frequencies:** 433.92 MHz only
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## Decoder Steps
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1. **Reset** — a short pulse begins the preamble.
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2. **PreambleSave/PreambleCheck** — count short/short pairs (≥13); a short→long transition seeds the leading sync bit (a 1) and enters data.
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3. **DataSave/DataCheck** — process duration pairs into bits; on a non-matching pair, run `check_completion` (discard sync byte, deobfuscate, validate additive checksum) and emit.
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## Encoder
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Supported (`subghz_protocol_encoder_mazda_siemens_get_upload`). Increments the counter byte, recomputes
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the checksum, obfuscates (interleave + XOR), then emits a 12-byte 0xFF preamble, a 50 ms gap, `0xFF 0xFF
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0xD7`, the 8 obfuscated bytes transmitted as `255 − byte`, a `0x5A` tail, and a trailing 50 ms gap.
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Manchester per byte: bit 1 → (H,L), bit 0 → (L,H) at te_short. As in the C, the decoder and encoder are
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not a clean raw-timing round-trip pair (the encoder targets a TX upload).
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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 obfuscate/deobfuscate XOR+interleave cipher layer (a true inverse, both parity branches), the
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field layout, and the TX upload smoke test.
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