Wikipedia:Reference desk/Archives/Computing/2016 October 14

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October 14

Quantum Computing: Phase vs. Anti-Phase Testing

Given two vectors (kets) $|x\rangle ,|y\rangle$ and I want to check if it holds that $|x\rangle =|y\rangle$ or $|x\rangle =-|y\rangle$ (there's a prior knoledge that it can't be neither). How can I check it in quantum computing methods? (I mean, what are the necessary quantum gates for that purpose?) 31.154.81.30 (talk) 07:48, 14 October 2016 (UTC)

I think that this doesn't make sense. A quantum system is described by one state vector, not two. If your system is $|x\rangle |y\rangle \in \{\,|y\rangle |y\rangle ,-|y\rangle |y\rangle \,\}$ (where juxtaposition means outer/tensor product) then there is no way to distinguish them, because state vectors are only physically meaningful up to an overall complex scalar factor. -- BenRG (talk) 02:51, 19 October 2016 (UTC)

BBC account email

Hi, I'm hoping someone else with a BBC account can help here. This morning I received the following email purporting to be from the BBC, and informing me they'd made changes to my account and that I would need to log in again because the changes had logged me out. I suspected it was spam/phishing so didn't act on it, and in any case when I went to the BBC website I was still logged in. Does anyone know if this is a genuine email or, as I suspected, a scam? If it is a phishing attempt, is there a BBC email address I can forward it on to for them to investigate? Thanks, This is Paul (talk) 16:27, 14 October 2016 (UTC)

the email

Hello, We've made a few improvements to your BBC account so we've had to sign you out. We’re all done now though, so please sign back in to get the best out of your BBC. Sign in Once you've signed in, UK residents will be able to: Vote on shows like Strictly Come Dancing Pause and resume BBC iPlayer programmes across devices UK residents and international users will be able to: Get notifications about stuff you care about Follow your favourite sports and teams Comment on news and sport articles And that's just for starters. See what else you can do. All the best, The BBC P.S. You can find out more about what's changed with your BBC account here.

This is the relevant page from the BBC site. The contact address for such matters is dpa.officer@bbc.co.uk for UK users, and dataprotection@bbc.com for international users. I think we can be confident that the e-mail isn't genuine - the address of the "Sign In" almost certainly doesn't go to a BBC website. Tevildo (talk) 18:10, 14 October 2016 (UTC)

• (edit conflict) @This is Paul: I compressed the text of the email, if you do not mind.

It could plausibly be that the BBC did make some changes but those did not invalidate your "stay logged" cookies. While it is impossible to say so with purely the text, the following checklist can help to determine if the email is genuine:

1. Hover over the links it contains (do not click!) and check if the URL they point to is indeed the bbc website, i.e. *.bbc.com. Note that domains in the URL are read "backwards", so for instance bbc.evilsite.com is not controlled by the BBC, though customerspam.bbc.com is. Note also that the text on which you click may differ from the resolved URL (look at the following trapped link: en.wikipedia.org).

   If you already clicked on the link and it goes somewhere fishy, your computer may be compromized.

2. Examine the email headers. Compare the Received fields from what a genuine BBC email (assuming you have one). They will be different if the email is forged; but the routing servers might legitimately have changed. The Reply-to field will 99% of the case be from the same domain (*.bbc.com) if genuine, but scammers can use an address they do not control (spammers routinely do).
3. Check the email for personal information. If the email contains your name, your account pseudonym, etc. (but not generic mentions like "your daughter", nor mentions that could easily be deduced from your email address) it is likely to be genuine.

In any case, I advise against reporting the message. Email spoofing is easy and it is near impossible to get to the real sender. Most likely, the BBC/the prince of Nigeria can (and thus will) do nothing to prevent being impersonated in such a way. Your message would be a good-faith but useless spam. Some companies (e.g. Microsoft) will provide reporting venues, but I doubt they make much of it. Tigraan^{Click here to contact me} 18:27, 14 October 2016 (UTC)

ok thanks for the response. The links are showing an address e.bbcmail.co.uk, while the original email came from bbcaccount@bbcmail.co.uk. A quick Google search suggests it is suspicious. I haven't clicked on it, and have no intention of doing so. If there's no point forwarding it on I'll just send it to the bin. Thanks again, This is Paul (talk) 21:03, 14 October 2016 (UTC)

Nil Einne below says the domain is likely legitimate, and gives some technical details. There should be multiple Received: fields.

Simple explanation of those: the original idea behind Received: fields is that each server adds a stamp "this came from here", and stamps accumulate as the message hops around on the internet. However, since the hopping around comes without any guarantee of confidentiality or integrity, a spam server can simply write false stamps saying it just relayed the email from a trusted source. That is the core of why email spoofing is easy. (That, and a few useful idiots). Tigraan^{Click here to contact me} 18:40, 16 October 2016 (UTC)

While you're right that you can't trust all received fields, you should be able to trust your mail server's received field (and if you can't you probably need a new mail provider) and it isn't something the spam servers can stop or change. Working out precisely which one is your mail server's received field isn't always easy but should normally be possible. Notably if there appears to be 2 received fields from your mail server receiving the mail from 2 different external mail servers it's likely there's something suspicious, and if there's only one you can probably be fairly confident it was added by your mail server and again unless they're really poorly designed it should indicate who they actually received the mail from. Modern mail routing doesn't really hop around anywhere like it used to, in fact SPF somewhat relies on that. And the vast majority of modern companies are going to be using mail providers with fairly strict standards. So even without SPF (or DKIM) and without previous emails for the company, it's often possible to figure out solely from the received headers whether it's likely the mail is genuine or not based on whether it's resonably possible the company is using the mail provider the mail came from. Of course you need to know what you're doing, and even then it may take a fair amount of work so may not be worth it in most cases, hence why automated measures like SPF (or DKIM) or much preferred, and even then there is a (probably fairly low if you know what you're doing) risk you are wrong so you shouldn't rely on it for anything important. Nil Einne (talk) 12:40, 17 October 2016 (UTC)

The BBC have definitely said something very similar recently [1]. They've also sent very similar emails [2].

Whether the email you refer to is genuine is impossible to say without at a minimum important headers, particularly all "Received:" headers. AFAICT You didn't mention what the from: address is, but note that e.bbcmail.co.uk has Sender Policy Framework although bbcmail.co.uk does not. I think e.bbcmail.co.uk also uses DKIM [3]. This similar email which I think (email-fake doesn't seem to let you view all headers or the email in code from AFAICT) is really from the BBC [4] appears to have e.bbcmail.co.uk as the from address.

Anyway the main point of this is if the from: domain is e.bbcmail.co.uk, any decent mail provider probably should have either rejected the email or at least warned you if the sender wasn't authorised. In any case, the headers will probably also tell you if the email passed SPF or DKIM. Although I admit I'm not sure if all good email providers ensure they remove SPF/DKIM validation headers which they didn't insert or alternatively always insert their own headers even when the domain has no SPF/DKIM so it's possible you can't trust those.

Of course, if the links are all to the real BBC site (I mean really to the BBC site not just looking like they are with some email clients), it's likely to be somewhat of a moot point whether the sender was really the BBC or not, unless BBC have majorly screwed up their website so a check of the I guess HTML code for the email will also be fruitful is revealing whether the email is actually a risk or not. Well unless the links are to the BBC external link filter and people ignore the warning they're visiting an external link I guess and then enter their details into the external link.

Personally I strongly suspect this is a genuine BBC email although I wouldn't suggest you click on the links unless you've looked sufficiently at your own email.

Nil Einne (talk) 02:48, 16 October 2016 (UTC)

P.S. In case there's some confusion bbcmail.co.uk is almost definitely a domain controlled by BBC [5] unless someone has been running a really long scam on a co.uk domain and no one noticed yet (even people trying to whitelist it), which I find very unlikely. Actually if bbcmail.co.uk really doesn't belong to BBC, it's the sort of thing it is worth letting the BBC know about. Nil Einne (talk) 02:57, 16 October 2016 (UTC)

The things these scammers get up to are hair - raising. This series is well worth a look, especially Series 7, Episodes 1 [6] and 12, Series 8, Episode 6, and 2016 Live: Episodes 1 and 3 (emails). Ironically, Gloria Hunniford, who fronts the programme, had all her money stolen. 86.128.234.239 (talk) 18:34, 19 October 2016 (UTC)

computer still shutting off

Hi, my computer is still shutting off for no apparent reason (see post earlier this week). I've checked the event logs, and I get some 6008s, very many in fact, seemingly each time it shuts down, but perhaps not (I'm not really sure, but it's a general pattern). But I don't get any 1074's or 1076's. In numerical order, they jump from 1032 up to 1101. I'm running a Windows Vista pc from 2011, sony vaio, i think 2gb of ram, minimal virus protection (free stuff only). Never had any major problems until now. Can anyone help? IBE (talk) 18:28, 14 October 2016 (UTC)

The previous discussion is archived at WP:Reference desk/Archives/Computing/2016 October 9#Computer shutting down for no apparent reason. -- ToE 13:49, 15 October 2016 (UTC)

Oh these problems can be so frustrating. I'm sure other editors will add to the following. First, you need to replace the battery with a fresh one. (2) You said you attempted to clean the fan. It is not the fan that needs de-fluffing but the heat-sink of the CPU. A long haired painters brush and a 'can of air' should sort that out – but if its really bad – take off the fan unit so that you have easy access to the heat sink. (3) The other possibly, is that your power supply is fluffing up and a temperature sensor is shutting it down. Some people shy away from delving it to such regions, because as it contains mains voltages and the manufacture wisely make it a little more difficult to open up an inspect... and in the process - makes it more troublesome to clean. Of course, you will know to unplug before doing any of this but remember to have a container handy to put any screws in so that you can find them again on reassembly. Also, try booting up with Live Linux disc to discount any OS problems.--Aspro (talk) 23:24, 14 October 2016 (UTC)

Well, as the problem was not clearly confined to its cause of hardware or software. Principally know, if You deacivate software updates, Your computer becomes vulnerable due somebody knows how to attack the machine. Regarding hardware, in a computer several voltages are generated. If one is not kept stable, a propper performance of the machine is not longer possible. Due missing knowledge and tools, much hardware is not being repaired. To separate issues on hardware from software, eighter reinstall the machine or try using an live CD. Note: hardware problems can not be complete detected by using a live CD, due live CDs often have a compatible driver support for hardware, only. It does not drive full performance of the used hardware. --Hans Haase (有问题吗) 09:56, 16 October 2016 (UTC)

Did you try the fan test ? That is, remove the case, and point a powerful box fan at the innards. If this stops it from shutting down, then you know heat was the problem. StuRat (talk) 14:14, 17 October 2016 (UTC)

Thanks, but no, because I'm a bit nervous about running it with the case off. I'm not a techie, although I have some experience with computers. I'm keen to eliminate all other things first. At any rate, it hasn't happened for a few days now, so it may have been dust. I cleaned the fan, and it still happened a couple of times, but maybe some other dust has worked its way out, and hopefully it's fixed. IBE (talk) 07:40, 18 October 2016 (UTC)

Galaxy S5 activation / SIM card troubleshooting

So I bought a Samsung Galaxy S5 off eBay, set up for Virgin Mobile, which is my carrier, but it lacked a SIM card. I bought two Virgin SIM cards for an S5 and attempted to activate it with each one but both times got Self Service messages about the SIM card locking. I called Virgin to see if they could associate my account with this new ICC ID and they told me the phone will only work with one ICC ID.

So phones that take SIM cards will only work with one card in the whole world? Is that true? Now I gotta sell the damn thing. NIRVANA2764 (talk) 23:18, 14 October 2016 (UTC)

A SIM lock allows the supplier of a mobile phone to restrict which SIMs it will accept, this is normally used when a customer buys the phone from the network, and is charged a monthly fee to pay for the phone. It sounds like the seller claimed that the phone is restricted to the Virgin Mobile network. However it appears that the phone is restricted to another network, or it has been reported as stolen, an has a IMEI block applied to it. A Virgin Mobile store will be be able to check why it is not working, or you could contact the seller. If it is a SIM lock, then the small mobile phone accessory/repair shops will be able to remove the lock for you, and you can then use it on any network. If it is a IMEI block, then you are out of luck, and should contact eBay. LongHairedFop (talk) 10:32, 15 October 2016 (UTC)

Thanks! NIRVANA2764 (talk) 22:26, 15 October 2016 (UTC)