we continue our research. we wrote a decoder that decodes the package. received parcels from different consoles. we know which button we pressed and sometimes the serial number of the remote control is written on the key fob itself. we have a set of decoded parcels. we translate it into BIN and start looking for similarities and differences
we notice that parcels from key fobs with serial numbers with similar serial numbers almost do not differ at the beginning.
the penultimate byte of the send is repeated in different sends when you press the same button (maybe this is the button code). the last byte is always different, but the same when the button is pressed again. so this is (presumably) the CRC of the send, so this is 1 byte, again assume that this is CRC-8 (maybe this is not so, maybe just the sum of all bytes with overflow or something else). we run the CRC-8 brute over the entire range of the polynomial and the start bit. and O miracle!!!