According to the papers leaked by Snowden, the NSA has the ability to intercept communications carried by submarine cables.

My question is: does Tor also use these submarine cables? So, can Tor be monitored through surveillance programs like PRISM or Upstream?


Imagine that the NSA has intervened all submarine telecommunication cables. I suppose Tor uses these cables. So, could the NSA spy on Tor's communications in this context?

(Forgive my English, English is not my mother tongue).

1 Answer 1


you can monitor the cable or the wireless packets, but they're encrypted, so to actually monitor the tor traffic you need to defeat the encryption algo at least three times in a row - because by default Tor uses 3 hops and so it makes a three-layer onions.

  • 2
    No. You need to defeat it at least once, at most three times and possibly not at all. This is an, at best, incomplete (and wrong) answer to a misguided question.
    – cacahuatl
    Jan 26, 2017 at 11:01
  • so, enlighten us, how precisely? intercepting cables means eavesdroping, i.e. a passive attacker. Catching unencrypted traffic on the exit node is a different problem, so how exactly "can Tor be monitored through surveillance programs like PRISM or Upstream" just using cables intercepting? I'm curious
    – Alexey Vesnin
    Jan 27, 2017 at 18:14
  • Intercept ingress and egress traffic, Tapping undersea cables nets a large percentage of international comms data. Correlate ingress and egress traffic, tie unencrypted egress traffic to ingress traffic. See plaintext, no decryption required.
    – cacahuatl
    Jan 28, 2017 at 1:36
  • unencrypted traffic IS insecure, so nothing to do with the undersea cables. The question was about how undersea cables that can be monitored can be a potential security risk. To properly implement corellation attacks(bandwidth watch) monitoring just these cables is not near enough to succeed. And speaking of Tor security the only potential risk is to catch Tor packets coming overseas: and all the private data in Tor are traveling in onions, so unless you can decrypt them - no risk of just intercepting any carrier, not just cables, data transmitted via Tor are safe
    – Alexey Vesnin
    Jan 28, 2017 at 13:24
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    They just carry traffic. If the traffic was sent across the cable, of course they could see it. Encrypted traffic is still revealing, HTTPS won't help. It's why people use Tor instead of just HTTPS on it's own.
    – cacahuatl
    Jan 30, 2017 at 20:18

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