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32

You have covered the main ones. In short: it's very hard, if not impossible, to effectively block a site you want. You can make it hard by using the techniques you've mentioned: blocking IPs, redirecting DNS, blocking HTTP requests to certain sites / containing certain keywords. These methods are thwartable by proxies (in the case of deep packet ...


11

"Efficiency" depends on your goals. An important point to be made is that all blocking techniques can be circumvented, at a price. For instance, an individual can use a satellite phone to get connectivity which cannot be blocked by his country, save by direct physical intervention of armed forces. But using such systems is quite expensive. Countries which ...


10

This topic has already been covered here and there. To sum up: If you simply overwrite the complete disk (as a block) with data (random, null bytes... it does not matter), then there may be parts of surviving data, which could potentially be recovered by extracting the chip and reading from it directly. You cannot know what data has survived without taking ...


5

Some research on this topic: Empirical Analysis of Internet Filtering in China (2003) For some 1,043 of sites tested, we confirmed that DNS servers in China report a web server other than the official web sever actually designated via each site's authoritative name servers. We call this phenomenon "DNS redirection," though others sometimes refer to the ...


4

It's a question of resources actually. If a country were willing to devote a enormous amount of time, money, and expertise to the problem, I believe it would be possible to effectively block a few select sites. The reasoning is that all the circumvention methods themselves need to be broadly publicized among the target audience to be successful. A ...


4

Depending on the applicable data privacy law in your country, you might have the right to request a company to send you all the personal information it collected about you. This usually works fine, though you have to send this request to each company you think is storing some data. Also, data privacy authorities often provide standard letter for this. There ...


4

The exit node does not know your IP address -- that's the whole point of onion routing. Rather, it knows which relay node to contact in order for the data to eventually get back to you. In order for your IP address to be revealed with certainty, the entire chain needs to be vulnerable; if the entry and exit nodes are both vulnerable, an attacker can make a ...


2

The answer is yes, he can see what you're doing on the internet when he is connected to your WiFi network. The encryption protocol used is pretty much irrelevant. Whilst WPA2 will generate a unique session key for each client association, if the attacker captures this he can still decrypt your traffic. Even if the attacker doesn't capture it, he can forge ...


2

TOR recently started to reject all the servers which have not updated their SSL. There is also initiative to block any servers that come online with unpatched SSL in the future. These cuts result in ~12% network capacity drop for Tor. That resulted from blocking ~380 servers. Below is an excerpt from the message on Tor's mailing list: I thought for a while ...


2

This looks like a bug. Actually, regardless of whether there was interception or not, this is bug: when you spy on someone, you certainly don't want to make that person aware of the spying. But in this case, I'd rather incline towards a more mundane buffering issue. In phone networks, especially mobile networks, audio data is split into individual packets ...


2

One censorship method that hasn't been mentioned yet is TCP Reset packet injection, which terminates undesired connections via forged TCP RST packets. The Great Firewall of China has been known to do this for years (source: http://www.icir.org/vern/papers/reset-injection.ndss09.pdf). Often this is used in conjunction with DPI, such as to do protocol ...


2

There is nothing in the "Snowden revelations" which even hints at any special NSA ability at breaking RSA. Even taking all that Snowden says as gospel, NSA is still at the same point as everybody else, meaning that breaking 1024-bit RSA is "theoretically feasible" but subject to the building of a very special machine whose design has been roughly sketched, ...


1

I made a 16384-bit master signing key with 4096-bit subkeys using a modified version of GnuPG about a week ago. Then I imported it into a trial version of Symantec Encryption Desktop (formerly PGP Desktop). The key (and all of its subkeys): will not encrypt, sign, or decrypt anything. cannot change password. cannot modify preferences (like encryption, ...


1

Your "master key" has value only insofar as its public part can be used to verify that which was signed with it; and this includes other people. For instance, your "master key" is your ultimate resource to revoke sub-keys. So if you mind about interoperability, then you cannot make the master key as big as you would wish, even if your GnuPG binary has been ...


1

A "master signing key" (ie your identity) should be safe enough for a lifetime, because ideally you don't ever want to change it, right ? Yes, that's the idea. I am considering using 4k keys for encryption and documents signing, and a 8k+ key as "master key". That means I will use my master key only to sign my owns keys, and other ppls keys. Also ...


1

You asked quite a lot of different questions here. I'll try answering each. Spoofing/sniffing: The cure is encryption. More specifically Public Key Infrastructure. Then B can't modify (or even decrypt) data that it's relaying. The only question here is how you want to implement the key exchange (so that it can't be attacked). Open ports: An open port is ...


1

Yes, an app can access either camera without requesting the user's permission (except in China as you found out). All apps have unrestricted access to view the camera feed of either the front-facing or rear-facing camera and take pictures/videos. However, access to the Camera Roll to save such media does require the user's consent. Most apps on the App ...



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