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unleashed-firmware/lib/lfrfid/protocols/protocol_electra.c
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2024-07-16 01:01:17 +03:00

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/*
* Electra intercom rfid protocol (Romania)
*
* Based on EM4100 protocol implementation from https://github.com/flipperdevices/flipperzero-firmware/blob/dev/lib/lfrfid/protocols/protocol_em4100.c
*
* Copyright 2024 Leptoptilos <leptoptilos@icloud.com>
*
* This program is free software: you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
* ------------------------------------------------------------------------------------------------------------------------------
* PROTOCOL DESCRIPTION:
* ------------------------------------------------------------------------------------------------------------------------------
* Electra intercom 125 kHz protocol based on 64-bit clock EM4100, but includes some extra data after base EM4100 data (epilogue)
*
* Epilogue size is 64 bits, but only first 16 bits matter. Rest 6 bytes - some filler data,
* that arbitrary change is not validated by the Electra intercoms
*
* There are curently three known types of epilogue:
* - 0x7E71AAAAAAAAAAAA (AA filler)
* - 0x7E71000000000000 (00 filler)
* - 0x0030AAAAAAAAAAAA
*
* First two epilogue bytes may be interpreted as EM4100 data continuation
* Nevertheless, these bytes have correct row parity bits, but have not correct collumn parity
* For example: 0x7E71AAAAAAAAAAAA epilogue:
*
* In binary: | 0b01111110 | 01110001 | 10101010 | 10101010 | 10101010 | 10101010 | 10101010 | 10101010 |
* In hex: | 0x7E | 71 | AA | AA | AA | AA | AA | AA |
*
* As EM4100 data:
* 0111 1 // 7
* 1100 0 // C
* 0111 1 // 7
* 1101 0 // here epilogue filler starts (from second bit)
* 1010 1 // there is no correct raw parity bits anymore
* 0101 0
* 1010 1
* 0101 0
* 1010 // and no correct column parity
*/
#include "bit_lib/bit_lib.h"
#include <furi.h>
#include <stdlib.h>
#include <toolbox/protocols/protocol.h>
#include <toolbox/manchester_decoder.h>
#include "lfrfid_protocols.h"
#define TAG "ELECTRA"
typedef uint64_t ElectraDecodedData;
#define EM_HEADER_POS (55)
#define EM_HEADER_MASK (0x1FFLLU << EM_HEADER_POS)
#define EM_FIRST_ROW_POS (50)
#define EM_ROW_COUNT (10)
#define EM_COLUMN_COUNT (4)
#define EM_BITS_PER_ROW_COUNT (EM_COLUMN_COUNT + 1)
#define EM_COLUMN_POS (4)
#define ELECTRA_STOP_POS (0)
#define ELECTRA_STOP_MASK (0x1LLU << ELECTRA_STOP_POS)
#define EM_HEADER_AND_STOP_MASK (EM_HEADER_MASK | ELECTRA_STOP_MASK)
#define EM_HEADER_AND_STOP_DATA (EM_HEADER_MASK)
#define ELECTRA_DECODED_BASE_DATA_SIZE (5)
#define ELECTRA_ENCODED_BASE_DATA_SIZE (sizeof(ElectraDecodedData))
#define ELECTRA_DECODED_EPILOGUE_SIZE (3)
#define ELECTRA_ENCODED_EPILOGUE_SIZE (sizeof(ElectraDecodedData))
#define ELECTRA_DECODED_DATA_SIZE (ELECTRA_DECODED_BASE_DATA_SIZE + ELECTRA_DECODED_EPILOGUE_SIZE)
#define ELECTRA_ENCODED_DATA_SIZE (ELECTRA_ENCODED_BASE_DATA_SIZE + ELECTRA_ENCODED_EPILOGUE_SIZE)
#define ELECTRA_DECODED_DATA_EPILOGUE_START_POS (ELECTRA_DECODED_BASE_DATA_SIZE)
#define ELECTRA_CLOCK_PER_BIT (64)
#define ELECTRA_READ_SHORT_TIME (256)
#define ELECTRA_READ_LONG_TIME (512)
#define ELECTRA_READ_JITTER_TIME (100)
#define ELECTRA_READ_SHORT_TIME_LOW (ELECTRA_READ_SHORT_TIME - ELECTRA_READ_JITTER_TIME)
#define ELECTRA_READ_SHORT_TIME_HIGH (ELECTRA_READ_SHORT_TIME + ELECTRA_READ_JITTER_TIME)
#define ELECTRA_READ_LONG_TIME_LOW (ELECTRA_READ_LONG_TIME - ELECTRA_READ_JITTER_TIME)
#define ELECTRA_READ_LONG_TIME_HIGH (ELECTRA_READ_LONG_TIME + ELECTRA_READ_JITTER_TIME)
#define EM_ENCODED_DATA_HEADER (0xFF80000000000000ULL)
typedef struct {
uint8_t data[ELECTRA_DECODED_DATA_SIZE];
ElectraDecodedData encoded_base_data;
ElectraDecodedData encoded_epilogue;
uint8_t encoded_data_index;
bool encoded_polarity;
ManchesterState decoder_manchester_state;
} ProtocolElectra;
ProtocolElectra* protocol_electra_alloc(void) {
ProtocolElectra* proto = malloc(sizeof(ProtocolElectra));
return (void*)proto;
}
void protocol_electra_free(ProtocolElectra* proto) {
free(proto);
}
uint8_t* protocol_electra_get_data(ProtocolElectra* proto) {
return proto->data;
}
static void electra_decode(
const uint8_t* encoded_base_data,
const uint8_t encoded_base_data_size,
const uint8_t* encoded_epilogue,
const uint8_t encoded_epilogue_size,
uint8_t* decoded_data,
const uint8_t decoded_data_size) {
furi_check(decoded_data_size >= ELECTRA_DECODED_DATA_SIZE);
furi_check(encoded_base_data_size >= ELECTRA_ENCODED_BASE_DATA_SIZE);
furi_check(encoded_epilogue_size >= ELECTRA_ENCODED_EPILOGUE_SIZE);
uint8_t decoded_data_index = 0;
ElectraDecodedData base_data = *((ElectraDecodedData*)(encoded_base_data));
//ElectraDecodedData epilogue = *((ElectraDecodedData*)(encoded_epilogue));
// clean result
memset(decoded_data, 0, decoded_data_size);
// header
for(uint8_t i = 0; i < 9; i++) {
base_data = base_data << 1;
}
// nibbles
uint8_t value = 0;
for(uint8_t r = 0; r < EM_ROW_COUNT; r++) {
uint8_t nibble = 0;
for(uint8_t i = 0; i < 5; i++) {
if(i < 4) nibble = (nibble << 1) | (base_data & (1LLU << 63) ? 1 : 0);
base_data = base_data << 1;
}
value = (value << 4) | nibble;
if(r % 2) {
decoded_data[decoded_data_index] |= value;
decoded_data_index++;
value = 0;
}
}
// copy first 3 bytes of encoded epilogue to decoded data
decoded_data[ELECTRA_DECODED_DATA_EPILOGUE_START_POS] =
encoded_epilogue[ELECTRA_ENCODED_EPILOGUE_SIZE - 1];
decoded_data[ELECTRA_DECODED_DATA_EPILOGUE_START_POS + 1] =
encoded_epilogue[ELECTRA_ENCODED_EPILOGUE_SIZE - 2];
decoded_data[ELECTRA_DECODED_DATA_EPILOGUE_START_POS + 2] =
encoded_epilogue[ELECTRA_ENCODED_EPILOGUE_SIZE - 3];
}
static bool electra_can_be_decoded(
const uint8_t* encoded_base_data,
const uint8_t encoded_base_data_size,
const uint8_t* encoded_epilogue_data,
const uint8_t encoded_epilogue_data_size) {
furi_check(encoded_base_data_size >= ELECTRA_ENCODED_BASE_DATA_SIZE);
furi_check(encoded_epilogue_data_size >= ELECTRA_ENCODED_EPILOGUE_SIZE);
const ElectraDecodedData* base_data = (ElectraDecodedData*)encoded_base_data;
const ElectraDecodedData* epilogue = (ElectraDecodedData*)encoded_epilogue_data;
// check electra epilogue. if em4100 header - break
if((*epilogue & EM_ENCODED_DATA_HEADER) == EM_ENCODED_DATA_HEADER) return false;
// check header and stop bit
if((*base_data & EM_HEADER_AND_STOP_MASK) != EM_HEADER_AND_STOP_DATA) return false;
// check row parity
for(uint8_t i = 0; i < EM_ROW_COUNT; i++) {
uint8_t parity_sum = 0;
for(uint8_t j = 0; j < EM_BITS_PER_ROW_COUNT; j++) {
parity_sum += (*base_data >> (EM_FIRST_ROW_POS - i * EM_BITS_PER_ROW_COUNT + j)) & 1;
}
if(parity_sum % 2) {
return false;
}
}
// check columns parity
for(uint8_t i = 0; i < EM_COLUMN_COUNT; i++) {
uint8_t parity_sum = 0;
for(uint8_t j = 0; j < EM_ROW_COUNT + 1; j++) {
parity_sum += (*base_data >> (EM_COLUMN_POS - i + j * EM_BITS_PER_ROW_COUNT)) & 1;
}
if(parity_sum % 2) {
FURI_LOG_D(
TAG,
"Unexpected column parity found. EM4100 data: %016llX",
bit_lib_bytes_to_num_be(encoded_base_data, encoded_base_data_size));
return false;
}
}
// encoded_epilogue_data lsb encoded
uint8_t epilogue_filler = encoded_epilogue_data[(ELECTRA_ENCODED_EPILOGUE_SIZE - 1) - 2];
for(uint8_t i = 0; i < ((ELECTRA_ENCODED_EPILOGUE_SIZE - 1) - 2); i++)
if(encoded_epilogue_data[i] != epilogue_filler) {
FURI_LOG_D(TAG, "Unexpected epilogue filler found: %016llX", *epilogue);
return false;
}
return true;
}
void protocol_electra_decoder_start(ProtocolElectra* proto) {
memset(proto->data, 0, ELECTRA_DECODED_DATA_SIZE);
proto->encoded_base_data = 0;
proto->encoded_epilogue = 0;
manchester_advance(
proto->decoder_manchester_state,
ManchesterEventReset,
&proto->decoder_manchester_state,
NULL);
}
bool protocol_electra_decoder_feed(ProtocolElectra* proto, bool level, uint32_t duration) {
bool result = false;
ManchesterEvent event = ManchesterEventReset;
if(duration > ELECTRA_READ_SHORT_TIME_LOW && duration < ELECTRA_READ_SHORT_TIME_HIGH) {
if(!level) {
event = ManchesterEventShortHigh;
} else {
event = ManchesterEventShortLow;
}
} else if(duration > ELECTRA_READ_LONG_TIME_LOW && duration < ELECTRA_READ_LONG_TIME_HIGH) {
if(!level) {
event = ManchesterEventLongHigh;
} else {
event = ManchesterEventLongLow;
}
}
if(event != ManchesterEventReset) {
bool data;
bool data_ok = manchester_advance(
proto->decoder_manchester_state, event, &proto->decoder_manchester_state, &data);
if(data_ok) {
/*
EM 4100 BASE DATA (64 bit) ELECTRA EPILOGUE (64 bit)
_________________________________ _________________________________
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | <- new data bit
--------------------------------- ---------------------------------
<- epilogue msb is carry bit to base data
*/
bool carry = proto->encoded_epilogue >> 63 & 0b1;
proto->encoded_base_data = (proto->encoded_base_data << 1) | carry;
proto->encoded_epilogue = (proto->encoded_epilogue << 1) | data;
if(electra_can_be_decoded(
(uint8_t*)&proto->encoded_base_data,
ELECTRA_ENCODED_BASE_DATA_SIZE,
(uint8_t*)&proto->encoded_epilogue,
ELECTRA_ENCODED_EPILOGUE_SIZE)) {
electra_decode(
(uint8_t*)&proto->encoded_base_data,
ELECTRA_ENCODED_BASE_DATA_SIZE,
(uint8_t*)&proto->encoded_epilogue,
ELECTRA_ENCODED_EPILOGUE_SIZE,
proto->data,
ELECTRA_DECODED_DATA_SIZE);
result = true;
}
}
}
return result;
}
static void em_write_nibble(bool low_nibble, uint8_t data, ElectraDecodedData* encoded_base_data) {
uint8_t parity_sum = 0;
uint8_t start = 0;
if(!low_nibble) start = 4;
for(int8_t i = (start + 3); i >= start; i--) {
parity_sum += (data >> i) & 1;
*encoded_base_data = (*encoded_base_data << 1) | ((data >> i) & 1);
}
*encoded_base_data = (*encoded_base_data << 1) | ((parity_sum % 2) & 1);
}
bool protocol_electra_encoder_start(ProtocolElectra* proto) {
// header
proto->encoded_base_data = 0b111111111;
// data
for(uint8_t i = 0; i < ELECTRA_DECODED_BASE_DATA_SIZE; i++) {
em_write_nibble(false, proto->data[i], &proto->encoded_base_data);
em_write_nibble(true, proto->data[i], &proto->encoded_base_data);
}
// column parity and stop bit
uint8_t parity_sum;
for(uint8_t c = 0; c < EM_COLUMN_COUNT; c++) {
parity_sum = 0;
for(uint8_t i = 1; i <= EM_ROW_COUNT; i++) {
uint8_t parity_bit = (proto->encoded_base_data >> (i * EM_BITS_PER_ROW_COUNT - 1)) & 1;
parity_sum += parity_bit;
}
proto->encoded_base_data = (proto->encoded_base_data << 1) | ((parity_sum % 2) & 1);
}
// stop bit
proto->encoded_base_data = (proto->encoded_base_data << 1) | 0;
proto->encoded_data_index = 0;
proto->encoded_polarity = true;
// epilogue
proto->encoded_epilogue = (proto->data[ELECTRA_DECODED_DATA_EPILOGUE_START_POS]);
proto->encoded_epilogue <<= 8;
proto->encoded_epilogue |= (proto->data[ELECTRA_DECODED_DATA_EPILOGUE_START_POS + 1]);
//fill bytes 2-7 by epilogue filler
for(uint8_t i = 2; i < ELECTRA_ENCODED_EPILOGUE_SIZE; i++) {
proto->encoded_epilogue <<= 8;
proto->encoded_epilogue |= proto->data[ELECTRA_DECODED_DATA_EPILOGUE_START_POS + 2];
}
return true;
}
LevelDuration protocol_electra_encoder_yield(ProtocolElectra* proto) {
bool level;
if(proto->encoded_data_index < 64)
level = (proto->encoded_base_data >> (63 - proto->encoded_data_index)) & 1;
else
level = (proto->encoded_epilogue >> (63 - (proto->encoded_data_index - 64))) & 1;
uint32_t duration = ELECTRA_CLOCK_PER_BIT / 2;
if(proto->encoded_polarity) {
proto->encoded_polarity = false;
} else {
level = !level;
proto->encoded_polarity = true;
proto->encoded_data_index++;
if(proto->encoded_data_index >= 128) {
proto->encoded_data_index = 0;
}
}
return level_duration_make(level, duration);
}
bool protocol_electra_write_data(ProtocolElectra* protocol, void* data) {
LFRFIDWriteRequest* request = (LFRFIDWriteRequest*)data;
bool result = false;
// Correct protocol data by redecoding
protocol_electra_encoder_start(protocol);
electra_decode(
(uint8_t*)&protocol->encoded_base_data,
sizeof(ElectraDecodedData),
(uint8_t*)&protocol->encoded_epilogue,
sizeof(ElectraDecodedData),
protocol->data,
ELECTRA_DECODED_DATA_SIZE);
protocol_electra_encoder_start(protocol);
if(request->write_type == LFRFIDWriteTypeT5577) {
request->t5577.block[0] =
(LFRFID_T5577_MODULATION_MANCHESTER | LFRFID_T5577_BITRATE_RF_64 |
(4 << LFRFID_T5577_MAXBLOCK_SHIFT));
request->t5577.block[1] = protocol->encoded_base_data >> 32;
request->t5577.block[2] = protocol->encoded_base_data & 0xFFFFFFFF;
request->t5577.block[3] = protocol->encoded_epilogue >> 32;
request->t5577.block[4] = protocol->encoded_epilogue & 0xFFFFFFFF;
request->t5577.blocks_to_write = 5;
result = true;
}
return result;
}
void protocol_electra_render_data(ProtocolElectra* protocol, FuriString* result) {
protocol_electra_encoder_start(protocol);
furi_string_printf(result, "Epilogue: %016llX", protocol->encoded_epilogue);
}
const ProtocolBase protocol_electra = {
.name = "Electra",
.manufacturer = "Electra",
.data_size = ELECTRA_DECODED_DATA_SIZE,
.features = LFRFIDFeatureASK | LFRFIDFeaturePSK,
.validate_count = 3,
.alloc = (ProtocolAlloc)protocol_electra_alloc,
.free = (ProtocolFree)protocol_electra_free,
.get_data = (ProtocolGetData)protocol_electra_get_data,
.decoder =
{
.start = (ProtocolDecoderStart)protocol_electra_decoder_start,
.feed = (ProtocolDecoderFeed)protocol_electra_decoder_feed,
},
.encoder =
{
.start = (ProtocolEncoderStart)protocol_electra_encoder_start,
.yield = (ProtocolEncoderYield)protocol_electra_encoder_yield,
},
.render_data = (ProtocolRenderData)protocol_electra_render_data,
.render_brief_data = (ProtocolRenderData)protocol_electra_render_data,
.write_data = (ProtocolWriteData)protocol_electra_write_data,
};
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