After reading a bunch of past stack exchange posts like  and RFCs , , and  I felt comfortable that a 32-byte key was sufficient for HMAC-SHA256.  However, I am implementing my code in C# and someone pointed out to me that the  recommends a 64-byte key:     The key can be any length. However, the recommended size is 64 bytes.   Is there any good reason to use a 64-byte key instead of a 32-byte key?
I'm trying to generate a secret key to be used for HMAC SHA-256 signature processing. I've seen many sample of keys with variable length from 32 characters to 96 characters.  What is the ironclad rule for this key size?
I understand why the Empire would want to start using more than one genetic template to create clone troopers, but why did it start using non-clone troopers instead of just continuing the cloning program?  It seems that with cloning they were able to use a training program (and genetic manipulation) that gave them completely loyalty (other than when the Kaminoan rebellion, where the Kaminoans had sabotaged the training programs).  Why stop using such troops and start using people that might question orders or aren't as easily controlled as clones were? I need to compile between two and four times before I see changes I make in the editor (TeXstudio) and each time I compile, a new .tex file is created with random letters and numbers at the end.   For example, If I create the file hello.tex and compile two to four times I'll get the file,   hello.tex.QU6664      then I make some small changes in the editor and compile two to four times I'll get the additional file,   hello.tex.Ak6664   After continuing to do this (each time compiling between two to four times before I see the changes I made), I now have many files that look like  hello.tex.QU6664, hello.tex.Ak6664, hello.tex.YX6664, hello.tex.sN6664, hello.tex.Ss6664, ...   A little bit of additional information (in case it's relevant): Everything was working fine up until a few days ago, i.e. only needed to compile once and only the file hello.tex was created. I still only get one .aux,  .synctex and .pdf files. I use TeXstudio to write and compile. I don't think it has anything to do with the bibliography (I tried removing bibliography altogether and still having the same problem).  How do I prevent these additional files from appearing and only compiling once like I used to? Has anyone had a similar problem? "whatever" as pure determiner? My dictionaries and references define, and I've always thought of, one of the functions of the word whatever as a "relative determiner."  In a sentence like, "I will help you in whatever way is possible,"  inserting the relative pronoun "that" between "way" and  "is", or replacing "whatever" with "the" - a pure, non-relative determiner - (I reckon) renders it ungrammatical:     *I will help you in whatever way that is possible.   *I will help you in the way is possible.   However, I do often encounter utterances like the first one above, such as:     My hope and intent is to contribute in whatever way that I can.   I wish to be of service to the local communities in whatever way that is possible.   where "that" is used, and thus "whatever" can be replaced by "the" without  making the sentences ungrammatical (if they are grammatical to begin with):     My hope and intent is to contribute in the way that I can.   I wish to be of service to the local communities in the way that is possible.   Is this usage of "that" with "whatever" wrong, though colloquial? Add links to official status pages in the read-only mode status message When the site is in read-only mode, I get a message like this:     This site is currently in read-only mode.   Would it be possible to update that message to provide links to these resources on SE's status:   : Official SE tweets on SE's status. : Official blog posts on SE's status. I simply can't figure out what the capacity of this circuit is.  I can do the math myself, I just need a hint how to create an equivalent circuit where it is obvious what is parallel and what is in series... How are the age restrictions followed by ICC for under 19 cricket tournaments? I have some doubts under this topic,   Can a player aged 19 play under 19 international cricket match? (Since 19 is not under 19) Consider a player having birthday during the series/tournament. How the age will be calculated for him? How to get sitelinks to appear on Google Search? Where did the disco repos go, or what is going on? Is there a way to change the restrictions passcode on an iPhone without restoring the phone? I haven't forgotten the passocde; I just want to change it. How do I download torrents? Tangent and Normal lines that pass through the origin Let $\alpha$ be a regular curve in $\mathbb{R}^2$ and let all of its tangent lines pass through the origin. Also, let $\beta$ be a regular curve in $\mathbb{R}^2$ and let all of its normal lines pass through the origin.   How can I show that $\alpha$ is contained in a straight line through the origin and that $\beta$ is contained in a circle around the origin?  I know that the tangent line $\alpha(t)$ is the line that points in the direction of the tangent vector $T(t)$ and that the normal line of $\beta(t)$ is the line that points in the direction of $N(t)$, but how can I put this all together to complete the proof? Ubuntu on 32-bit UEFI - optimal solution I have a computer (Asus T200TA) with 2G RAM and 32-bit UEFI [Yep, what a wonderful idea to put 32-bit UEFI!]. I have two options:   Install a 64-bit system, boot manually and install grub-efi-ia32. Drawback: 2G is not much, systems with such low RAM are said to run better on 32-bit systems. Install a 32-bit version. (but from my state of knowledge it's not trivial to boot)   Which option would be better? Current sensing nA to mA I need to sense the current of a target  through various periods of its on/sleep/off state and then need to send this data back to another interface MCU to read out the value. They will be both on the same board, powered by 5&nbsp;V USB.  However these are the requirements I have:   5&nbsp;V USB PSU Must be able to sense currents in the range of nA to mA with high    accuracy/precision. (I figure 1&nbsp;nA to 500&nbsp;mA) Only measure the current of the target MCU and not the interface. Must output maximum 3.3&nbsp;V interface MCU   I have looked at available options and current sense amplifiers by Texas Instruments can't sense nA due to higher bias currents. So therefore I feel I would need a precision amplifier.  However I am stuck on how to proceed with this because, I need to somehow have a automatic dynamic current range and I am fairly new to current sensing and am not really sure on all the specifics. OpenLayers and OSGB 1936 (CRS 27700) I've been working with loads of shapefiles projected according to OSGB 1936 (CRS 27700). The project CRS is set to EPSG:27700 and "On the fly reprojection" to EPSG:27700 is set (I keep this as a default as I work with OSGB 1936 95% of my time).  I decided to download OSM layers from the OpenLayers plugin. When I load this, the EPSG in the bottom right of the screen goes from EPSG:27700 to EPSG:3857   Question 1: should this be happening anyway as it would suggest that the whole project has been re-projected to EPSG:3857?   As soon as the OSM layer is loaded it's way out of alignment but a quick pan seems to bring it altogether quiet nicely.   What I have noted is that (Question 2), if I try to re-specify the CRS to 27700, then the shapefiles "move" by a few tens of meters with respect to the OSM. Does this suggest that QGIS is doing a second re-projection (from what to what?)?   Also (Question 3), does it mean that if I import another shapefile that would be originally a dataset digitised with EPSG:27700 it would be re-projected to EPSG:3857 because the CRS in the bottom right of the screen was set to EPSG:3857 after the OSM import. This is all a bit confusing and logic would suggest that the import of a non-ESPG:27700 (project default CRS) should not go and change the EPSG setting in the bottom right of the screen. Anita Graser's book says on page 34 "Your project CRS will automatically be changed to Pseudo Mercator when you load a background map using the OpenLayers plugin option".   Does that mean there is no way of keeping ESPG:27700 active in the project when importing basemaps from OpenLayers? If so, what alternatives are there?  What I am trying to bottom out is to understand the correct way of importing basemaps (usually Google, Bing or OSM through the OpenLayers plugin) into my projects (always EPSG:27700) without losing alignment and getting layers to correctly re-project. I'm trying to support greater use of QGIS in my company but don't want to lose credibility by promoting the use of a tool that is misaligning datasets. Don't get me wrong. QGIS is a great tool and I am very fond of it but importing layers with different CRS's is quite common these days and getting this right from the start is half the job done.  I did quite an extensive Google search before posting and didn't come up with a recent, clear cut answer to my questions above. There is a bit of content out there on problems with older versions of QGIS, PROJ4, etc. but nothing recent for QGIS 2.0 so worth an update. Why is Cat5/Cat5e Ethernet cable rated 100MHz? As the questions says, is there any specific reason why Ethernet cable is rated 100MHz?  For a 100Mbps Ethernet the data rate is 100Mbps, and the baud rate is 125Mbaud, because of the specific line coding that it uses. What is the relationship between 125Mbaud rating of data transfer and 100MHz rating of cable?  Thank you. Which colors make you hungry I am working on a new brand, which is all about food.   What colors should we use for the logo and website?   I keep reading that red makes you hungry, but i would like to stay away from that color. All of our competitors must have read the same articles. Previous question:    That was when my buttons died.  On other days, my text dies.    And some times it's just italics.    Now, I like blaming @skiwi for this, and he's often nearby when it happens.  But today, he's not here, and it happened again.    I'm running Windows 8 and using Chrome 40.0.2214.94 m.  Refreshing and such does not fix the issue.  Inspect element -> console -> error log:  http://chat.stackexchange.com/chats/8595/messages/new Failed to load resource: the server responded with a status of 409 (Conflict) http://i.stack.imgur.com/2ZJdJ.png?s=128&amp;g=1&amp;g&amp;s=16 Failed to load resource: the server responded with a status of 502 (Bad Gateway) http://i.stack.imgur.com/boUZp.jpg?g&amp;s=16 Failed to load resource: the server responded with a status of 502 (Bad Gateway) http://i.stack.imgur.com/U8P3C.jpg?s=128&amp;g=1&amp;g&amp;s=32 Failed to load resource: the server responded with a status of 502 (Bad Gateway) http://i.stack.imgur.com/boUZp.jpg?g&amp;s=16 Failed to load resource: the server responded with a status of 504 (Gateway Time-out) http://chat.stackexchange.com/messages/19891816 Failed to load resource: the server responded with a status of 409 (Conflict)   What's going on here?  I should note, I can view italics by selecting, then alt-tabbing:    So it reeks of a client-side issue. What's hiding the text from me?  EDIT:  30 april 2015 it happened again =/ Is there a way to see the history of questions protected by me or another user? Having a record of all actions taken on a site, as is provided by the &quot;activity&quot; and &quot;votes&quot; tabs of our profile, comes in handy very often. Perhaps the most common case is being able to find a question I've interacted with in the past, to see if anything has changed about it. This applies to questions a user has protected as much as anything else. Users are theoretically encouraged to unprotect questions when it's no longer necessary, as emphasized , but in practice they often do not. In many cases it's hard to blame them: unless they specifically marked it as a favourite, the site doesn't keep any record of the question to allow them to find it again. We should help users more easily review their own protections in the future.    For personal review, the votes tab is adequate, but there may also be value in displaying this publicly in the activity tab. There may be users with a history of repeatedly protecting questions over-eagerly. It would be useful to be able to review other users' protection histories to see if this is the case. Even if this is not available to regular users, it may be helpful to moderators, unless their user activity views already allow them to filter down to see this. How do I access previous promise results in a .then() chain? Looking for sci-fi novel I read about humanity finding alien station on orbit of Earth I am looking for a novel that I'd love to re-read it with my wife (my 13-year old self must be proud of me I guess). Key Plot points The plot was about humanity finding an alien station on an orbit of Earth. (I'm not sure if it wasn't Moon itself). On this station there were thousands of ships ready to travel so there rose a company that paid people to get on those ships and explore the galaxy. The problem was humans didn't understand how to steer those ships so they had to rely on preset targets. Of course there was no telling where particular ship was to go and fair amount of them never returned. Chronology and other relevant information I read it as an early teenager back in early 2000s. It was Polish translation of a foreign (possibly English) story. I think (not sure) that the book wasn't new at the time. It was just one of those books you dig out in a library and take to see if it's good. I don't recall cover either and even if I did it'd be of the Polish version. Additional information could be that the narration was led along the psychoanalytics of the main protagonists where he relives his memories from inside the station and his journeys.