Wikipedia claims “Russian reconnaissance planes in the area had been monitoring satellite communications for quite some time trying to match Dudayev's voice signature to the existing samples of his speech” (https://en.wikipedia.org/wiki/Dzhokhar_Dudayev#Assassination)

If that’s correct, it required decryption.

However, that Wikipedia page continues “Dudayev's phone signature and coordinates were also reportedly passed to the Russians by the NSA after U.S. President Bill Clinton's meeting with Russian President Boris Yeltsin”, so it may have been specifics of his phone (if so, what? Slight frequency and/or timing deviations that fingerprint a specific device?), not of his voice.

> if so, what? Slight frequency and/or timing deviations that fingerprint a specific device?

How many satellite phones were operating in Chechnya at the time? It's not like the handset was beam forming or performing fancy modulations to look like static.

In the right frequency--in publicly known frequencies--the handset would shine like a torch.

> In the right frequency--in publicly known frequencies--the handset would shine like a torch.

To clarify: if a satellite phone of a particular manufacturer uses a known set of frequencies and is talking to a specific satellite and you know the rough area where you are looking for phones from that manufacturer you can filter out the rest of the electromagnetic radiation and then all you are left with is instances of phones of that type (or other devices using the same set of frequencies).

It's not quite as easy as picking out a torch at night and to get accurate coordinates you will need to do some more measurements and some math but this is all definitely doable, especially if the call lasts for more than a few minutes if the device you use to scan for the phone is mobile (such as on a plane) because with every passing second your baseline is getting longer (and thus your accuracy).

https://en.wikipedia.org/wiki/Direction_finding

Radio amateurs do this sort of thing for sport, it's called fox hunting ( https://en.wikipedia.org/wiki/Transmitter_hunting ), and with experienced hunters it can be done pretty quickly if the target is stationary.

That section is not supported by any external references.

I've done some digging and this pretty important information (if true) was added unsourced in this edit:

https://en.wikipedia.org/w/index.php?title=Dzhokhar_Dudayev&...

It probably should be removed without any kind of reference to corroborate it, it's been more than 15 years since that edit has been made and there is zero evidence for this.

> If that’s correct, it required decryption.

Probably but not _necessarily_ - if someone's vocal cadence was somehow visible in the encrypted modulation then that could be an identifier.

https://en.wikipedia.org/wiki/Traffic_analysis

This is why militaries like to use DSSS communication technologies. It makes detection by these kinds of systems very difficult. The state of the art is offline processing of recorded "noise" on HPC server farms. In a "launch/guide missile" context, this is way too late, even if you find a coherent signal.

This was true probably up to Iraq war. Good example http://www.milspec.ca/radspec/prc-343.html https://www.cryptomuseum.com/radio/selex/prr/index.htm Ordinary DECT home cordless phones could be considered as secure at the time :)

Nowadays we have enough compute power in a laptop with connected SDR to render this moot security by obscurity.

> Nowadays we have enough compute power in a laptop with connected SDR to render this moot security by obscurity.

Can you provide some sort of example of how a laptop+SDR was used to discriminate something equivalent to a military-grade DSSS signal (i.e. one in which the pseudo noise function and its parameters are classified)?

If you know the PN function, I agree that it is trivial to detect/recover the transmission.

USRP came out in 2005. Nowadays wide coherent multi radio SDRs are readily available in portable form factor. Beginner setup (sadly limited to <1.8GHz) started shipping recently https://www.crowdsupply.com/krakenrf/krakensdr

https://www.youtube.com/watch?v=z9RkPt6uVQ4 now add ability to do phase correlation

His Wikipedia article claims that the Russians were trying to "match his voice signature", which implies being able to listen to the call itself somehow.