4 ms·

Note that encrypted traffic, indistinguishable from noise, is almost always then encoded for transmission in a format that contains redundancy (frequently, ther

by caf 14y ago

Note that encrypted traffic, indistinguishable from noise, is almost always then encoded for transmission in a format that contains redundancy (frequently, there are more than one such layer). For example if you electrically sniff an ethernet cable over which only SSL traffic using AES is being sent, the first thing you will notice is a concentration of energy near 200Mhz. Then you may see bursts of a Manchester-encoded signal; further study reveals the regular structure of Ethernet headers and trailers, along with IP, TCP and SSL headers. Only within that will you hit a brick wall at the AES data itself. Even if the payload is encrypted it should be possible in most cases to detect a modulated transmission.

lusr 14y ago
That's a good point. In effect, if we look at this from the perspective of the OSI model, you're saying that whereas the application layer may contain encrypted data the lower layers may contain structured data. So the logical question that follows: is there any reason to believe aliens might use encryption all the way down to the data link layer? Maybe our neighbours are all at war and need to disguise and protect signals from each other? Have you read ithkuil's comment? http://news.ycombinator.com/item?id=4188160 http://news.ycombinator.com/item?id=4188160
- caf 14y ago
  Yes, but spread spectrum modulations are very much a minority among all our transmissions, so I see no reason to expect any different from other civilizations.
  - ithkuil 14y ago
    Today yes. But imagine that our technology gets refined in the following 10k years, even assuming no more technological breakthroughs, but only incremental improvements. Even today we use some technology which is not really necessary to solve a given problem, just because it uses off the shelf components which are cheaper even if more complicated (e.g. a embedded cpu instead of dedicated and simpler electronics)

by caf 14y ago

lusr 14y ago

That's a good point. In effect, if we look at this from the perspective of the OSI model, you're saying that whereas the application layer may contain encrypted data the lower layers may contain structured data. So the logical question that follows: is there any reason to believe aliens might use encryption all the way down to the data link layer? Maybe our neighbours are all at war and need to disguise and protect signals from each other? Have you read ithkuil's comment? http://news.ycombinator.com/item?id=4188160 http://news.ycombinator.com/item?id=4188160

caf 14y ago
Yes, but spread spectrum modulations are very much a minority among all our transmissions, so I see no reason to expect any different from other civilizations.
- ithkuil 14y ago
  Today yes. But imagine that our technology gets refined in the following 10k years, even assuming no more technological breakthroughs, but only incremental improvements. Even today we use some technology which is not really necessary to solve a given problem, just because it uses off the shelf components which are cheaper even if more complicated (e.g. a embedded cpu instead of dedicated and simpler electronics)