Wikipedia:Reference desk/Archives/Computing/2014 June 13

Welcome to the Wikipedia Computing Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

June 13

World of Tanks

Why is World of Tanks considered an MMO? I am told it is a series of 10 v 10 or 15 v 15 engagements. --Tarcil (talk) 00:55, 13 June 2014 (UTC)

I am a big player of this game. Keep in mind that while the normal public match is 15v15, there are also clans, and Clan Wars, which allow you to attack and defend land based upon a map of the U.S. Diplomacy and rivalry plays into it. There are also other modes, including team battles and historical battles. But yes, the general gist of the game is 15v15 for 15 minutes. I refuse to try to decipher what the actual definition of an MMO is, but I hope this will help. Justin15w (talk) 14:40, 13 June 2014 (UTC)

Simplest algorithm that cannot be reversed easily?

What is the most straightforward algorithm in cryptography (in real life or just for educational purposes) that cannot be reversed easily?OsmanRF34 (talk) 18:24, 13 June 2014 (UTC)

What do you mean by "cannot be reversed easily"? Some algorithms, like fingerprints, are not intended to be reversed. Others are meant to be decoded by a recipient. The complexity of the algorithm will tend to increase along with the difficulty of reversing it, so it's hard to pick a point and say "this is the most straightforward cipher that is hard to break". How hard is "hard"? —Noiratsi (talk) 19:26, 13 June 2014 (UTC)

I'm not sure if it's the kind of thing you're thinking of, but the Diffie–Hellman key exchange is a one-way function that formed the basis of a lot of modern cryptography. —Noiratsi (talk) 19:38, 13 June 2014 (UTC)

Is Cryptographic hash function what you're asking about? Katie R (talk) 19:47, 13 June 2014 (UTC)

Or Trapdoor function? --Phil Holmes (talk) 10:08, 14 June 2014 (UTC)

One of the conceptually most simple is prime factorization. Basic idea is, I pick two large prime numbers, p1, and p2. Then, finding m=p1*p2 is trivially easy. But, if only m is known, finding p1 and p2 can be quite computationally intensive. Going one way is easy, the other is hard, so these are also sometimes known as one-way functions. SemanticMantis (talk) 14:12, 16 June 2014 (UTC)

Why would he say a corrupt file stopped the scan?

I use McAfee with Windows Vista and Internet Explorer 9. Several weeks ago my virus scan just stopped. It was at less than 1 percent and I couldn't restart it (though if I had waited, the scan went just fine the next day after I turned the computer back on). I went to tech support (by chat) and when I described the situation the person asked if I was seeing one file name stay on the screen. Yes, in fact, the file name is supposed to change many times a second. He said that was a corrupt file which would have to be removed. I knew not to do that myself because I didn't know what that file did. He sent me to a different tech support site (which started with chat but was changed to phone at some point) which would require me to pay, $70 US, or several times that for a year's subscription. But I got put on hold for a very long time and I had to rejoin the real world, so I hung up. The next day, I decided to try and see if I could do a scan and it completed with no problems identified. That was a month ago. All my weekly scans have completed with no problems identified.— Vchimpanzee · talk · contributions · 20:20, 13 June 2014 (UTC)

I think it more likely the index which it uses to find the files was corrupt, so it couldn't find the next file to scan. Apparently when that happens, rather than give a useful error, it just freezes. Of course, there could be other explanations, like that it ran out of memory. That's always what I suspect when a program just freezes up like that, because then it lacks the memory needed to do anything else, including displaying an error message. StuRat (talk) 23:14, 13 June 2014 (UTC)

What's likely going on here?

I have an iPhone 3GS. I have a Bytech charger you can plug into a car charger or a wall plug, and you plug a USB cable into it. The Bytech has a little red LED on it which is lighted when the thing is plugged into a power source. I have had two 30-pin-to-USB white cords break in the following way: charging my iPhone by connecting the white cords to the Bytech charger plugged into my car's charger port, the iPhone would periodically stop being in charge mode and then go back to being in charge mode (the red LED never went off; there would be stretches of time when it was all plugged in, the red LED on, but the phone not in charge mode). Again, the red LED never went off. Then eventually it exited charge mode and never went back into charge mode. I looked at the 30-pin side of the cord and could see burnt out pins (I haven't counted which pins are the burnt ones, but it's about 1/16" thick burned section just right of center when you look at the plug with the pins facing you and the (---) image on the plug facing up. Before the cords died, while they still led to spotty performance when plugged into the car, if I used them connected to the Bytech plugged into a wall plug inside, everything worked fine. As I said, this happened twice in exactly the same way. So I think this pretty definitively singles out the charger port in the car. But my wife's Samsung Galaxy S4 Active plugged into the same Bytech charger plugged into my car's charger port with a standard USB to micro USB cord has never had any problems. Then I got a non-Apple third party 30-pin-to-USB cord and tried connecting my iPhone to the car charger port and it again went temporarily to not charging while plugged in and the red LED showing it still had power, but I'm done sacrificing cords while the cord I have still works. Is my car charger port spiking high voltages to which 30-pin connecters are more susceptible to breakage than micro USBs? Will Apple devices go into non charge mode when the voltage goes too high? Peter Michner (talk) 21:54, 13 June 2014 (UTC)

I don't know about 3GS, but some newer iPhones have ways of detecting if they are plugged into an "official" charger, and that might be part of the issue, unless you are sure that this behavior only happens when charging in the car. See some discussion of off-brand chargers here [1], and links therein. SemanticMantis (talk) 16:55, 16 June 2014 (UTC)