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This is some impressive work.
Earlier quoted context omitted.
Modern microcontrollers can be had in the sub-$5 range that support hardware implemented encrypting algorithms. Mostly it's a worthless feature but we aren't far out from it being more or less standard even in the $0.20 guys. The bigger issue is that the entire point of this system is to remove cost of deployment and maintenance for cheap highly distributed lo-fi systems. The cost of keying all those devices for encr…
> Also, why do you even want to encrypt it in the first place? I want to encrypt and authenticate any and all wireless gadget data because I've been paying attention to the last 5 years of defcon talks.
"So, we reverse-engineer the LoRa physical layer using the patents filed by Semtech [27, 57], which is the key LoRa chipset manufacturer. We also use the Semtech 1276 starter kit [10] that provides an interface to transmit LoRa packets with various bitrates and an arbitrary payload. Finally, we analyze the transmissions from the LoRa chipsets on a USRP." This is some impressive work.
- Decoding LoRa: Realizing a Modern LPWAN with SDR [1]
- Presentation on this work from GRCon16 [2]
- Slides from the above presentation [3]
[1] https://pubs.gnuradio.org/index.php/grcon/article/download/8...
[2] https://www.youtube.com/watch?v=-YNMRZC6v1s
[3] https://static1.squarespace.com/static/54cecce7e4b054df1848b...
I worry about encryption of sensitive data. I don't doubt it can be done, but can their "twenty-cent" chip handle it without messing up its lightweight low-power nature?
It says regarding CSS "That makes even faint LoRa signals easy to distinguish from background noise, which fluctuates randomly". Is CSS better than FSK than in this respect or..? Edit: http://www.akermann.bg/files/Semnrs/H2016/Module3.4_100km%20... Says "Spreading codes does not improve sensitivity over FSK systems, for usable datarates you get similar sensitivity using standard FSK modulation"
From years of experience selling, supporting, and installing 900MHz ISM radios, I can tell you this is not the case in many, many places (it describes a greenfield application more or less correctly, though). 900MHz is heavily used in the US and describing the noise as "background" or "random" is disingenuous at best. I'd like to see someone install a LoRa hub on a tower with several other 900MHz radios (common) and see how well it works.
It says regarding CSS "That makes even faint LoRa signals easy to distinguish from background noise, which fluctuates randomly". Is CSS better than FSK than in this respect or..? Edit: http://www.akermann.bg/files/Semnrs/H2016/Module3.4_100km%20... Says "Spreading codes does not improve sensitivity over FSK systems, for usable datarates you get similar sensitivity using standard FSK modulation"
>background noise, which fluctuates randomly From years of experience selling, supporting, and installing 900MHz ISM radios, I can tell you this is not the case in many, many places (it describes a greenfield application more or less correctly, though). 900MHz is heavily used in the US and describing the noise as "background" or "random" is disingenuous at best. I'd like to see someone install a LoRa hub on a tower w…
Earlier quoted context omitted.
Modern microcontrollers can be had in the sub-$5 range that support hardware implemented encrypting algorithms. Mostly it's a worthless feature but we aren't far out from it being more or less standard even in the $0.20 guys. The bigger issue is that the entire point of this system is to remove cost of deployment and maintenance for cheap highly distributed lo-fi systems. The cost of keying all those devices for encr…
> Also, why do you even want to encrypt it in the first place? I want to encrypt and authenticate any and all wireless gadget data because I've been paying attention to the last 5 years of defcon talks.
I worry about encryption of sensitive data. I don't doubt it can be done, but can their "twenty-cent" chip handle it without messing up its lightweight low-power nature?
Since backscatter systems depend on on an RF source, I wonder if work has been done on encrypting the source signal (pseudorandom bit pattern for example), then modulating the random stream at the device and decoding the backscattered signal at the receiver - essentially a streaming XOR cypher.
All that said, it's not a fundamentally bad idea. Pseudo-random xor encoding of signals is a technique used all the time to increase orthoganality between signals for a variety of encoding schemes.
Earlier quoted context omitted.
Since backscatter systems depend on on an RF source, I wonder if work has been done on encrypting the source signal (pseudorandom bit pattern for example), then modulating the random stream at the device and decoding the backscattered signal at the receiver - essentially a streaming XOR cypher.
In this system the RF source you are sending is effectively the IF component for the sensor's Tx chain. Because it is so high power and such a clean pilot tone, the sensor can eliminate it's IF generating oscillator and output amplifier by just mixing the data onto the receive pilot tone and retransmitting it. This is how the sensor is made so cheap and low power. If the pilot tone was cyphered, it wouldn't mean the…
Yes, thanks for the response!
http://www.ambuj.se/LoRea-CR.pdf
LoRa while achieves impressive sensitivity levels, this is for very low bitrates of tens of bps. For any practical data rate the sensitivity levels are similar to FSK.