Wikipedia:Reference desk/Archives/Computing/2010 April 10

= April 10 =

Excel
I have developed an excel spreadsheet to perform a certain function which uses the Solver add-in that requires being macro enabled. Is there anyway I can encrypt this spreadsheet so that it can be distributed without revealing the equations and/or processes yet still allow data to be entered and changed? 71.100.3.207 (talk) 00:12, 10 April 2010 (UTC)
 * Simple answer: no. Long answer, as long as you are distributing the code and the calculations are being performed on a remote computer, you have no way of stopping people with the necessary skills and desire reversing engineering and working out what your code does. Forget Solver, even you design some sort of fancy standalone program, it's not going to work. People who design applications and games sometimes go to great lengths to make it difficult for people to reverse engineer their code (generally not so much because they want to keep their code super secret but because they want to stop people copying their program or using it without the copyright owner's permission and to do that, they need to make it difficult for people to reverse engineer the copy protection) but none of these ever last for ever unless no one is interested enough in breaking it. If you really want to stop people knowing the internal algorithms, run the code on a server so all the calculations happen on your server and of course make sure you secure your server well. Even then if your code is simple, someone might be able to work out what it's doing by using the inputed values and results. You'd likely want to limit the number of answers over a defined time period to to make this more difficult although someone could use a botnet so you can't do it simply per IP which means people could easily DOS your server. Of course if no one cares about your code, even if you don't encrypt it no one may actually know what it does. (BTW in case it isn't clear, that last comment applies to whatever level of protection you do use, the more interesting people find your code, the more likely it is someone is going to bother to break any protection you do use. Of course there are many other factors.) Nil Einne (talk) 00:53, 10 April 2010 (UTC)


 * If you are really worried about proprietary equations the easiest way to keep them proprietary is to not have them execute as distributed code. One could imagine an application that was either web-based or could interface with a script running on a web server that would be running the actual equations and just pumping out answers. --Mr.98 (talk) 02:31, 10 April 2010 (UTC)
 * Just ran a server side test script so in theory all computations could be done server side. Is there anyway to run Excel server-side and then submit data to it using HTML forms and client-side script? 71.100.3.207 (talk) 13:51, 11 April 2010 (UTC)
 * You can't encrypt the formula, but you probably can obfuscate it.--Chmod 777 (talk) 03:54, 10 April 2010 (UTC)
 * That article tells me how little I really know about programming and computers compared with most anyone in the world. 71.100.3.207 (talk) 13:51, 11 April 2010 (UTC)
 * On a very simple level, in Excel you can put formulae in hidden columns, then save the spreadsheet with a password to modify. This means that the user can open it only in read-only form, but can still enter data in unhidden cells and read the result, but they can't see the formulae used.  This is probably at too simple a level for your purposes, and there might be a way round the protection (but I haven't found it).    D b f i r s   07:25, 10 April 2010 (UTC)
 * I've never been able to recover a password protected sheet without the password so you are probably right. If I can't find a way to run Excel on the server then this is probably what I'll try. 71.100.3.207 (talk) 13:51, 11 April 2010 (UTC)
 * Excel allows unlimited tries at the password, and cracking software is available on the internet, so make sure that the password is not in any dictionary. Is the rumour true or is it just a myth that Microsoft have a "back door" password for the NSA to use?    D b f i r s   16:16, 11 April 2010 (UTC)
 * Such rumours exist for most things, for something as famous as Excel, you can bet there would be ample discussion if there were any real evidence. In any case, Excel encryption until 2007 at least has evidentally been very weak so who needs a back door? However more to the point, am I missing something here or do people really think passwords to modify are useful for protecting documents against all but the most uninformed users?
 * Passwords to modify are nearly always next to useless since if you can open the document, you just need something which understands the document and ignores the requirement for a password. In this particular case, from a quick search it appears even Microsoft does that. If you save the document as a copy/another file, the password disappears even though you never entered the password. A quick test confirms this behaviour (although I didn't bother to make a hidden column). So even Excel only tries to protect the original file and even that has flaws . Somethings like Adobe Acrobat aren't so kind but finding apps which remove the password isn't hard even if they may violate the DMCA in the US. For some sort of obscure proprietary document format, perhaps no one will have bothered yet, but that's not much protection.
 * Note a key point here, if you're talking a local computer which someone has complete and long term physical access to, without encryption a password is close to useless. (This example is very similar since the file is on such a computer as your distributing it to people who have such computers.) If you're talking a password to modify, either you have no encryption of the content you're trying to protect (most common by far) or you do have encryption but it's tied to something that's universal. You inherently cannot tie it to the password to modify, since people need to be able to open the document without the password.
 * Similarly eBooks which often have DRM usually in the form of an equivalent of a 'password' (not really what most would call a password but rather a key which the software automatically obtains from the ebook seller and which is tied to the computer) to open but which anyone who can read the book obviously has (since they can open the book) are similarly nearly always broken eventually and the encryption removable. In these cases we do have encryption which is tied to a specific key but the key is available so you just need to break the encryption, and the decryption algorithm is obviously in the program which can open the file so... Baring that of course you can take advantage of the 'analog hole' i.e. screenshot then OCR the book.
 * Of course as I mentioned above, since Excel is computing the results on the local computer, it would definitely be possible to recover what it's doing internally and you could also easily bruteforce it and try to work out what the formula is as another alternative. (Somewhat equivalent to the 'analog hole'.)
 * Nil Einne (talk) 01:56, 12 April 2010 (UTC)
 * I seem to get differing quality of security with differing orders of setting protection and in different versions of Excel. I still have one spreadsheet with protected columns and cells (created some time ago) that none of the methods seems to crack, but I'm sure Nil Einne is correct that there will be a way round my protection, so I withdraw my advice to use Excel unless you have very honest customers!    D b f i r s   08:25, 12 April 2010 (UTC)
 * Did you use some sort of macro protection? If so, this may not be crackable with default tools. If you're just using a password to modify, can't you just save it as a new file, open the new file and then unhide the columns? (Or to put it a different way, are you saying the password to modify stays around even after you save it again? If not, what's stopping you unhiding the columns?) Nil Einne (talk) 17:02, 13 April 2010 (UTC)
 * I don't think I used macro protection, but the sheet was created years ago, so I can't remember. I think it was just a password to unprotect cells or columns.  The sheet doesn't allow me to unhide columns, and saving it to a new file doesn't change this.  I thought I could reproduce the effect with a password to modify, hidden columns and protected cells, but, as you said above, this doesn't seem to work.  Fortunately, I have a copy of a very similar sheet without the protected columns, so it is not important to crack the protection, but I wish I could remember how I did it.    D b f i r s   20:34, 13 April 2010 (UTC)
 * Was investigating this myself before I saw your post and that combined with reading it now I think there's some confusion. I've never really bothered with password but it seems there's a password to protect and password to modify (and also a password to open of course). You mentioned a password to modify but not protect but I now presume you did protect or both. A password to modify seems to be easily defeatable even from within Excel as I mentioned. A password to protect is different and isn't quite so easily defeatable although there are various tools (which you mentioned?) which I didn't bother to try.
 * However in my case in Excel 2007 there is a fundamental flaw (perhaps intentional?) in the way it works which I'm guessing would apply to your case even if you can't work out how to defeat the protection. Specifically, while you can't select the locked cells with the mouse or keyboard, you can enter the cell in the name box and see the contents (but not modify it).
 * Of course you could hide the cells in an odd place but you should be able to see the referenced cells in the unprotected parts which give you the output (since the output is coming from the hidden data plus whatever variables you provide) so unless there's some way of obscuring that then it's not much work. Well you could make like 1000 references or something so it takes a long time to find it which will add some work but ultimately a dedicated person can probably find it even from within Excel and without any additional tools. (You could also use macros/scripting in a variety of ways, e.g. to hide the namebox although if the macros aren't essential to the file, then just disabling macros should defeat this.)
 * BTW, if you're interested in a basic test of the effectiveness of the protection, something to try is a different app which understands Excel documents as I mentioned a while back. In my test, Google Docs doesn't appear to care about the password for protection or locked cells and the hidden cells are easily unhideable. Won't work if the worksheet is larger then the Google Docs maximum although something like Open Office may be just as easy (but downloading & installing something may seem a bit much if you don't care hence why I tried/suggested Google Docs).
 * Of course it's possible you were trying the wrong tools if you were trying tools to defeat a password to modify, you need tools to defeat a password to protect. If there is a password to modify, you should be asked for this on opening the document but just in case you may want to save the document as a copy when open as readonly (without entering the password) before trying the password to protect tools. One caveat is many of the tools are trying to find the password, these are obviously more likely to have problems then ones just to remove/defeat it.
 * Nil Einne (talk) 21:12, 13 April 2010 (UTC)
 * Yes, you are correct about the fundamental flaw! I'm kicking myself for not thinking of something so obvious!  And I was getting confused between password to modify and password to protect.  I meant to take a copy of my protected spreadsheet today when I had access to Open Office (but I forgot it).  I think I'll just admit that you were right that there is no real protection in Excel.    D b f i r s   22:20, 13 April 2010 (UTC)

Google Street View
How do I get to see the "Google Street View" view of a location? Even for places for which I know there is a Street View available, when I look at the Google Map for that locality, it dosnt say anything anywhere about how to see the Street View. What's the secret? Thanks 89.242.144.8 (talk) 13:41, 10 April 2010 (UTC)
 * On top of the zoom bar is a little yellow man. Drag him off of his place and streets with Street View available will turn blue; drop him on a street and the appropriate picture will appear. It's not very intuitive, I know -- when Street View first came out I believe you clicked a Street View button, and a camera icon appeared on every Street View city, allowing you to click on a street to view an image. I dunno why they fixed something that wasn't broken. Xenon54 / talk / 13:59, 10 April 2010 (UTC)


 * And if the man is gray rather than yellow, that means there is no streetview available for the area shown. -- Finlay McWalter • Talk 14:07, 10 April 2010 (UTC)

In some areas there is only Street View pictures for major roads, although here in England nearly every road has had the pictures taken. Chevymontecarlo. 10:08, 11 April 2010 (UTC)


 * Another method is to zoom in past max zoom level and it automatically zooms into street view - a bit of a pain if you don't want street view and aren't paying attention. -- k a i n a w &trade; 22:03, 11 April 2010 (UTC)

Memory leak (or something similar)
On a windows xp computer memory use (as reported by task manager (performance tab)) has gone up to 1.6GB, but in process tab, there are no suspicious processes, which would report large memory use (even with "show processes from all users" selected). This large amount of memory must be allocated by SOME process. How to identify that process? -Yyy (talk) 16:21, 10 April 2010 (UTC)


 * You can kill each non-suspicious process, at least the ones which aren't vital, and see when the problem goes away. A reboot will also likely solve the problem, but not necessarily tell you what it was. StuRat (talk) 16:46, 10 April 2010 (UTC)


 * Also check whether you are looking at the memory amount or the virtual memory amount. The performance tab shows your VM page file usage, whilst by default the processes tab shows the physical rather than virtual memory usage. Go to View --> Select Columns and tick the VM box. Zunaid 19:37, 10 April 2010 (UTC)


 * Looking at consumed virtual memory amount helped. Restarting that process reduced memory use almost by a gigabyte. Thank you. -Yyy (talk) 04:29, 11 April 2010 (UTC)


 * Which process was the problem ? StuRat (talk) 04:39, 11 April 2010 (UTC)


 * DC++ (v0.75) -Yyy (talk) 07:55, 12 April 2010 (UTC)


 * Thanks; good to know that the next time this happens. StuRat (talk) 18:49, 12 April 2010 (UTC)

iTunes is sentient?
Lately, I've been noticing iTunes automatically changing song information. Usually, it manifests in a several songs having their genre changed to "other" when they didn't have a genre to begin with. However, I just noticed that it changed a song called "Brazos del Sol" to "Envidia," as well as filling the artist as "Eugenia León" and the album as "TROVADORES." What's going on here? How do I stop it? How long 'til iTunes becomes Skynet?-- The Ninth Bright Shiner 19:52, 10 April 2010 (UTC)


 * Have you got iTunes set to retrieve track information from CDDB? It basically identifies and pre-fills in information about songs for you as you rip them (my understanding is it can analyse the file and find it even if you've not ripped it from the cd). ny156uk (talk) 22:15, 10 April 2010 (UTC)


 * Yeah, it's set to do that. I've turned that setting off, and I'll see if anything suspicious happens. And I was just starting to overhaul my music organization...good thing I haven't started yet!-- The Ninth Bright Shiner 03:30, 11 April 2010 (UTC)

transfer files from old to new computer
I would like to find an easy way to put all of the saved information from my old computer to my new one. I don't have a paid service to back up files. Is there a disc or flash I can use and how should I do it? Any ideas? —Preceding unsigned comment added by Harmony7120 (talk • contribs) 21:36, 10 April 2010 (UTC)
 * Depending on how much you have to transfer, the three easiest options would be A) transfer the files over a home network, B) put everything from the old system onto a flash drive and sneaker net it over to the new system, or C) get an ethernet cable and network the two systems (if they're not already on the same network). Dismas |(talk) 23:32, 10 April 2010 (UTC)


 * There are also stand-alone disk drives; you might use one if you have too much data to fit on one or two loads of a flash drive. They're more expensive, but you are more likely to be able to do it all in one shot, and they're a good idea for making your own backups anyway.  —Preceding unsigned comment added by 165.106.221.124 (talk) 00:00, 11 April 2010 (UTC)
 * Take a screwdriver, unscrew the hard drive from your old computer and plug it into your new computer. This is not the easiest way but you get the fastest file transfer rate. F (talk) 12:02, 12 April 2010 (UTC)

http://news.bbc.co.uk/1/hi/8600493.stm - What computer?
Hi, What computer is in the picture at the top of this article? I've searched for all the computers mentioned in the article but none of them are the one from the picture. Thanks for your help. 86.176.96.242 (talk) 23:38, 10 April 2010 (UTC)


 * I don't think the item that you can see all of is a computer -- I think it's a "dumb terminal", i.e., a machine with a screen, keyboard, and input/output capability for 8-bit ascii characters. These were often used on 8-bit computers like the Altair; such a machine would have a "serial port" (or more than one) and the computer would have input/output capability on that port, so that any "dumb terminal" could be connected to it.


 * The article mentions the subject's connection to the "Altair 8800"; it was certainly of this era, and I *think* it needed such a terminal as an interface, but am not sure. The terminal appears to be sitting on a box that *might* be an Altair, but that's really just speculation.  It would make sense, though, that the photographer and/or editor of the picture/article would not know what part of the equipment was significant, and therefore might leave out the part that was actually associated with the subject.  To a non-computer person, the distinction between a terminal and a computer is a bit esoteric.  —Preceding unsigned comment added by 165.106.221.124 (talk) 23:58, 10 April 2010 (UTC)


 * Looks like a Lear-Siegler ADM-3A Winston365 (talk) 00:07, 11 April 2010 (UTC)


 * I agree, it's an ADM-3 (maybe a 3A, maybe not - they look identical). What you're looking at isn't a computer - it's more or less a keyboard, CRT screen and text-only "graphics card" all in one.  It connected to the actual computer through a serial port - the computer just had to send the text it wanted to display and the ADM-3 would mindlessly display it.  At the time they were common, they were replacements for teletype machines - and were often called "glass teletypes".  The ADM-3 was a relatively early example of this kind of device. SteveBaker (talk) 04:14, 11 April 2010 (UTC)

Wow, thank you all very much for your help. 86.179.132.38 (talk) 13:36, 12 April 2010 (UTC)


 * This LA Times article has a wider view of the same photo, showing that the terminal is indeed perched on top of what appears to be an altair 8800b. --  Tom N (tcncv) talk/contrib 04:54, 14 April 2010 (UTC)