So I'm looking into public WiFi security in places such as hotels, coffee shops etc. It seems the current standard is just to use open wi fi connections in many of these locations. I would assume this is for a number of reasons:


Simple for the company - the provider does not need to train their workers in basic network security, don't need to manage keys or anything really, just plug the router in and go. Also costs the company less because of this.
Convenient for the user - the user doesn't have to concern themselves with trivial things like security, they just want to get straight to their online banking and shopping in a public place!
Ignorance - the person adding the free WiFi simply has no idea of the security risks involved, or they are dumping the responsibility of security onto the user, it's their data/money/identity after all


So, first question. In your experience, is it true that most coffee shops, hotels, airports typically use an open connection, or are protected networks more commonplace now?

If it is the case that most are unprotected, are there any other reasons as to why this is the case, beyond the ones above that I've listed?

Second question, assume a coffee shop with an open network, all traffic is extremely easy to sniff. Now picture the establishment upgrades it to WPA2/AES secured network. Is the network really that more secure? 

Sure attackers can no longer easily sniff the network from down the street, but how hard is it for them to go in, buy a coffee and get the current key. Even assuming the keys are changed daily, repeats are never used, and they are complex enough to take months to crack, any attacker could just buy a coffee and connect to the network right? Or even get the key through social engineering, or just get a friend to get a coffee and the key.

I understand that WEP, WPA2 etc. all do encryption at a network (as opposed to user) level of granularity. I.e. if someone has the key, they can now decrypt all traffic on the network, so we're back to the problem that an attacker can read all traffic as if it was an open network, and it's already proven to be trivial to get the key. So, with this in mind, is an unlocked encrypted network equivalent to an open network? What sort of attacks could a hacker do on a WPA2 secured network? Could you do a man in the middle attack as easily as on an open network? Is it possible to create a rogue AP with the SSID and key, advertised with the same encryption standard, as possible with the open network?

Thanks for reading this lengthy post, and thanks in advance for answers to any of my three questions!

Instead of continuing in the comments, I think I will just answer your real question, which I understand to be - why is using WPA/WPA2 Personal with a public SSID and Passphrase not more secure than having an open network, and why doesn't WPA/WPA2 Enterprise work in the coffee shop scenario.  

If the passphrase was public (as it would be in this scenario) and WPA/WPA2 personal is in use, anybody who has the passphrase and SSID name can decrypt anybody else's wireless traffic, as long as they can capture the initial 4-way handshake for that client (which occurs when connecting to the network).  If someone wants to decrypt someone's future traffic but did not monitor their client's initial 4-way handshake, they can simply force a new handshake between that client and the AP using a targeted deauthentication, at which point you would be able to capture the new 4-way handshake and decrypt all of their future traffic.  Of course, if the client under attack were to use a VPN, SSH tunnel, TLS, or some other strong encryption mechanism over the wireless, that traffic would be protected to the extent that the mechanism that they chose allows.  

The reason why their traffic can be decrypted is that WPA/WPA2 personal creates a pairwise master key from the passphrase and SSID used when logging in.  The PMK is then used to create a Pairwise Transient Key and Groupwise Temporal key, where the PTK is unique per client and the GTK is shared for all currently connected clients (for broadcast traffic).  This PTK can be derived from the PMK using information from the 4-way handshake (which is negotiated in plain text).  Therefore, if you are able to sniff the 4-way handshake, you can get the information used to derive that client's PTK from the PMK that you already know because you know the passphrase and SSID (usually by doing PBKDF2(Passphrase, SSID, ssidlen, 4096, 256)).  

WPA enterprise doesn't work well because everyone would need a way to authenticate, whether credentials (EAP-PEAP), certificate (EAP-TLS), or other (various other EAP modes), and this wouldn't support the coffee shop's goal of providing free wireless access to nearby individuals.  
