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I was told that using Tor and/or a VPN is always a tradeoff of privacy and anonymity. I'm wonder what combination of Tor, VPNs (paid or free), and proxies can help minimize this risk.

For example, if you use ISP -> VPN -> Tor, your ISP won't know you're using Tor, and your VPN provider won't know what your traffic is (encrypted), only that it's going into Tor network. However, the Tor exit node will see all your traffic in plain-text, depending on HTTPS use, and if that's really a secure option you should trust.

So, I'm wondering, would it be better to do ISP -> VPN -> Tor -> VPN to hide traffic from the Tor exit node? Does that gain you anything, or expose you in anyway? Basically with the first VPN you can hide your Tor usage from your ISP, with Tor you gain anonymity, and with the second VPN you hide your data from the Tor exit node.

But does this have any advantage over just using a second VPN? For example: ISP -> VPN -> VPN. It seems like your first VPN would hide your origin from the second, and the second would hide your data from the first.

  • How can I hide my plain-text data from a Tor exit node?
    • (Is HTTPS alone an acceptable solution?)
  • Is using another VPN an acceptable solution?
  • Does this have any advantage over just chain-linking multiple VPNs together?

Bonus points:

  • What kind of traffic slowdown/overhead will this cause? (anybody's personal experience)
  • Dear, it is not all IT design and issues that de-anonymize you, you should consider money trail for any paid VPN. Also do not forget about malware, it can put in vain any encryption you think you may used. Also the data could be stored indefinitly and decrypted over extended period of time. So the question is what is your time horizen? If your time horizen is in weeks or months encryption may work but if it is in years do not bet on it. – Roya Jun 26 '14 at 17:10
  • If you feel you truly like VPN, Make sure to use multihop routing VPN before and/or after the Tor. – Roya Jun 26 '14 at 17:19
  • That is a lot to consider. I apologize if this question is a bit broad, I may do some major edits in the future to narrow it down an make it more "answerable", while generating separate questions for the other remaining details. You also made me think about my personal threat level; I guess when I comes down to it there really is no airtight way to protect yourself against certain three-letter gov't organizations. (eg. Camp Delta, Camp Echo) I will be back soon! – IT Bear Jun 26 '14 at 23:16
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If strong anonymity is what you want, use Tor. Reaching the Tor network through a VPN does not increase privacy or anonymity. It merely shifts knowledge about Tor usage from your ISP (and relevant government) to the VPN (and relevant government). You choose based on which you trust more (or distrust less).

Tunneling a VPN through Tor decreases anonymity in at least two ways. First, it creates a persistent Tor circuit, which increases vulnerability to various attacks that exploit long-lived circuits. For example, see Johnson et al (2013) Users Get Routed: Traffic Correlation on Tor by Realistic Adversaries.

Second, as Roya notes, there may be a money trail for paid VPN services. You can reduce that risk by paying with Bitcoins that have been thoroughly anonymized via Tor. But even if you wash your Bitcoins through a chain of anonymous wallets, using multiple anonymous mixing services, there is still some risk.

Given that, I see only two situations where tunneling a VPN through Tor makes sense: 1) accessing sites that block Tor exit nodes; and 2) using apps that require UDP traffic. Even then, it's best to use a free VPN, such as SecurityKISS, which can be set up via Tor, and where there's no money trail.

Using nested chains of VPNs provides stronger anonymity than a single VPN, even a multi-hop VPN. However, if there were three one-hop VPNs in the chain, your anonymity would at best be comparable to restricting your Tor client to using just one circuit. Using nested VPN chains instead of Tor makes sense only when better performance (higher bandwidth and lower latency) is more important than stronger anonymity.

  • Very interesting analysis. – Roya Jul 2 '14 at 3:38

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