Between an open Wi-fi AP and wired/wireless tethering with iPhone, which would be more secure?

[kylera]

I'm leaning towards tethering, but I'd like to get some solid reasoning for one way or another.

EDIT: I'd like to pose a different question, but it's similar to my OP, so I'm just going to edit my post.

Out of the following scenarios:

• MBA->Open wi-fi
• MBA->WPA2 Personal (followed by captive portal where I need to log in)
• MBA->iPhone 6S via Bluetooth
• MBA->iPhone 6S via Lightning
• MBA->iPhone 6S via Wi-fi

How would they rank in terms of security, as well as battery usage? Obviously MBA->open wi-fi ranks at the bottom in terms of security, but I'm curious to see how the others fare.

 

[Mernak]

From most secure to least
1. MBA -> Lightning iPhone: Physical connections are pretty resilient to even reading data unless you have a more specialized set up really near by, and the only real concern is someone broadcasting a cell signal and intercepting that way (though some stuff would be logged by your cellular provider)
2. MBA -> Wi-Fi iPhone: I believe the default Wi-Fi for tethering is WPA2, and you control the access point
3. MBA -> BT iPhone: not sure exactly what the encryption standard for BT is currently, but even if it is exactly as strong, the BT connection is going to be slower, so the same set of actions would give an attacker additional time.
4. MBA -> WPA2 Wi-Fi: you have an additional security threat with a router/modem you have no control over and could be controlled by a bad agent
5. MBA -> Open Wi-Fi: Yeah...

If you are serious about security, the best would probably be tethering via lightning cable , and then connecting to a home (or trusted) VPN so that the initial connection could be logged by your cellular provider, but after then not, then having you home VPN running something like a TOR to anonymize your data even from your ISP.

As far as battery usage (best to worst), it's probably a toss up between the wi- fi connections (technically, there is an additional encryption/decryption step for WPA2, but it should be negligible), then Lighting (with BT and Wi-Fi off, USB connected but not charging), then I think BT (assuming you are using BTLE, which was iPhone 4S and above iirc), then iPhone with Wi-Fi