I am in the process of working on a decentralized application using IPFS and OrbitDB. IPFS uses 2048 bit RSA keys for the Node runtime peer-id and secp256k1 for read/write access in OrbitDB. For secp256k1 there exists a method for deterministically generating keys (bip39 mnemonic phrase).   Let's say I take an existing RSA implementation and replace the RNG with a seeded RNG which is seeded with the mnemonic phrase from above. Assuming I didn't roll my own implementation, aside from swapping out the RNG, how secure would this be? Are there any obvious flaws with this approach?
Background info: I am planning on making a filehost with which one can encrypt and upload files. To protect the data against any form of hacking, I'd like not to know the encryption key ($K$) used for a file, so the user will have to asymmetrically encrypt $K$ and send it as well. The reason for this double encryption is that you can still share (individual!) files with other accounts by encrypting $K$ with the public keys of those users, too.  My problem is: How can a user can get a public and private key without the server saving/knowing the private key and without the user having to remember a passphrase of 250 hex characters?  Question: Is there a way to derive a key pair from a password, like PBKDF-2 does for symmetric encryption? Suggestions on rearranging the cryptographic steps in an easier way are welcome, too.  Alternatively: It is also possible to encrypt the private key with a PBKDF-applied password and store it on the server, but I'd like to keep things 'simple'. ;)  Note: At this point I don't care if it requires RSA, ECC or an obscure cryptography scheme.
How to convert local time string to UTC? What is the effect where some objects are a single bright color but the rest is black and white? There is an option to filter only one color (R,G,B,Y) in my camera. What I want to know is can this effect be achieved in photoshop? And what is this called? I tried googling monochrome and came up with nothing. My camera calls it part color. Adding Multiple Maps in QGIS Composer? Convert date to another timezone in JavaScript How to help a toddler overcome the fear of water on head? Do the beacon lighters really live on top of the mountains? Following this image I found online:    Do the beacon lighters really live on top of the mountains?  It seems really cold on top of some of these mountains and there are no villages or whatsoever. Exponent and abelian groups What exponent $e$ can guarantee the group to be abelian? Are there any known results except the case $e = 2$? Thanks for help. Distribution of $Z_n=n \log\left(\frac{\max\left(X_{(n)},Y_{(n)}\right)}{\min\left(X_{(n)},Y_{(n)}\right)}\right)$ The random variables $X_1,X_2,...X_n,Y_1,Y_2,...Y_n $ are independent and $U(0,a)$-distributed. Determine the distribution of $$Z_n=n\cdot \log\left(\frac{\max\left(X_{(n)},Y_{(n)}\right)}{\min\left(X_{(n)},Y_{(n)}\right)}\right)$$ where $X_{(n)},Y_{(n)}$ denotes $n$th order variable.  This problem is giving me a headache. The answer is that $Z_n$ is $\text{Exp}(1)$-distributed. But i can't derive that conclusion. I'd like to show you my derivation, but its so long and contains so many integrals and fractions that it would take a while to write it here. But basically my approach was to derive the distribution of $M=\max(X_{(n)},Y_{(n)})$ and $L=\min(X_{(n)},Y_{(n)})$. I get the following cdf's: $F_M=(F_X\cdot F_Y)^n=(F_X)^{2n}$ and $F_L=1-(1-(F_X)^n)\cdot (1-(F_Y)^n)=1-(1-(F_X)^n)^2$ ,  correct? $F_X $ stands for the cdf of $X_i$  Then i define the random variable $T=\frac{M}{L}$ and compute its cdf to finally be able to derive the distribution of $Z_n=n\cdot \log(T)$. But thats where i think everything goes wrong. Any help appreciated, thanks. Headphones microphone is not working I'm trying to use my headphones with my Ubuntu 13.10. My headphones are Nokia BH-905i, which can be connected via Bluetooth or green+pink wires.  If I use bluetooth, voice quality is terrible or microphone doesn't work. If I try to choose "Headset" option from In and Out tabs in Sound Settings, they're disabling each together.  In Out tab, I'm using "High sound quality A2DP", because it betters voice quality.  How could I get my microphone working? Sound out works fine. I really tried hard to do this on my own, but I keep failing ... Using multi-column and multi-row commands confused me. I know some of you might frown upon such a request but I really need help getting this table implemented .. So I'm sorry if I upset anyone.  My preamble has :   \documentclass[12pt,a4paper]{report} \usepackage[lmargin=3.81cm,tmargin=2.54cm,rmargin=2.54cm,bmargin=2.52cm]{geometry} \linespread{1.5}     Is there a way I can convert this from excel to LaTeX form ? I tried an add-in before but it didn't work for me. Also online generators cannot combine cells the way I want them (unless I didn't find a better table generator ? ) An arithmetic function is defined as follows:$f(1)=1$,  $f(2k)=k$ and $f(2k+1)=f(k)+f(k+1)$. When (for which $k$) is $f(k)$ even?  While it is obvious that $f(4n-1)=f(4n)=2n$, therefore $f(k)$ is even for $k=4n$ and $k=4n-1$, which is possible to prove using induction (isn't it?), I don't know how to prove the converse.  I tried to solve the recurrence or make use of constant difference between certain elements of the sequence $\ldots$ What am I missing?  Thank you. Radical of $\mathfrak{gl}_n$ I find it intuitive enough that the radical of $\mathfrak{gl}_n\mathbb F$ is the scalar matrices, but I have trouble finding an easy, but complete proof:  Proof. Let $\mathfrak s$ denote the scalar matrices. Clearly $\mathfrak s\subset\mathrm{rad}(\mathfrak{gl}_n\mathbb F)$. Suppose that $\mathrm{rad}(\mathfrak{gl}_n\mathbb F)$ is generated by more than one element, so that $X\in\mathrm{rad}(\mathfrak{gl}_n\mathbb F)$, but $X\notin\mathfrak s$. We can change basis such that $\mathrm{rad}(\mathfrak{gl}_n\mathbb F)$ is upper-triangular. (The change of basis leaves the scalar matrices invariant.) Then $X$ is upper-triangular.  I want to conclude that there exists a $Y\in\mathfrak{gl}_n\mathbb F$ s.t. $[X,Y]$ is not upper-triangular. How can I see that $Y$ always exists, except by waving hands? introduces  which will allow the introduction of new literal syntax based on existing literals (int, hex, string, float) so that any type will be able to have a literal presentation.  Examples:  // imaginary numbers std::complex&lt;long double&gt; operator "" _i(long double d) // cooked form {      return std::complex&lt;long double&gt;(0, d);  } auto val = 3.14_i; // val = complex&lt;long double&gt;(0, 3.14)  // binary values int operator "" _B(const char*); // raw form int answer = 101010_B; // answer = 42  // std::string std::string operator "" _s(const char* str, size_t /*length*/)  {      return std::string(str);  }  auto hi = "hello"_s + " world"; // + works, "hello"_s is a string not a pointer  // units assert(1_kg == 2.2_lb); // give or take 0.00462262 pounds   At first glance this looks very cool but I'm wondering how applicable it really is, when I tried to think of having the suffixes _AD and _BC create dates I found that it's problematic due to operator order. 1974/01/06_AD would first evaluate 1974/01 (as plain ints) and only later the 06_AD (to say nothing of August and September having to be written without the 0 for octal reasons). This can be worked around by having the syntax be 1974-1/6_AD so that the operator evaluation order works but it's clunky.   So what my question boils down to is this, do you feel this feature will justify itself? What other literals would you like to define that will make your C++ code more readable?    Updated syntax to fit the final draft on June 2011 Found a similar question , but with some minor differences. Is it archaic to use have you in sentences such as this:     John : I think we can see it with a specially crafted telescope.   Mary : Have you such a telescope?   instead of     Mary : Do you have such a telescope?   Is it still used in official and casual conversations? I'm getting these errors ramdomly, and I don't know if its normal or not.   [39441.061856] ata3.00: failed to read SCR 1 (Emask=0x40) [39441.061866] ata3.01: failed to read SCR 1 (Emask=0x40) [39441.061892] ata3.15: exception Emask 0x10 SAct 0x0 SErr 0x280100 action 0x6 frozen [39441.061897] ata3.15: irq_stat 0x08000000, interface fatal error [39441.061904] ata3.15: SError: { UnrecovData 10B8B BadCRC } [39441.061910] ata3.00: exception Emask 0x100 SAct 0x0 SErr 0x0 action 0x6 frozen [39441.061917] ata3.01: exception Emask 0x100 SAct 0xe SErr 0x0 action 0x6 frozen [39441.061923] ata3.01: failed command: READ FPDMA QUEUED [39441.061933] ata3.01: cmd 60/a8:08:b0:48:62/00:00:00:00:00/40 tag 1 ncq 86016 in [39441.061940] ata3.01: status: { DRDY } [39441.061944] ata3.01: failed command: READ FPDMA QUEUED [39441.061953] ata3.01: cmd 60/a8:10:b0:49:62/00:00:00:00:00/40 tag 2 ncq 86016 in [39441.061959] ata3.01: status: { DRDY } [39441.061963] ata3.01: failed command: READ FPDMA QUEUED [39441.061972] ata3.01: cmd 60/58:18:58:4a:62/00:00:00:00:00/40 tag 3 ncq 45056 in [39441.061978] ata3.01: status: { DRDY } [39441.061987] ata3.15: hard resetting link [39441.608302] ata3.15: SATA link up 3.0 Gbps (SStatus 123 SControl 300) [39441.609090] ata3.00: hard resetting link [39441.929246] ata3.00: SATA link up 3.0 Gbps (SStatus 123 SControl 320) [39441.929333] ata3.01: hard resetting link [39442.249184] ata3.01: SATA link up 3.0 Gbps (SStatus 123 SControl 320) [39442.263242] ata3.00: configured for UDMA/133 [39442.277570] ata3.01: configured for UDMA/133 [39442.277725] ata3: EH complete   I'm also pasting smartctl -a for ,  and .  Thanks in advance for your help. Why does the set of all singleton sets not exist? Conditions for vertical circular motion If a bob attached to a string is swinging in vertical circular motion, we say that the bob leaves the circular path when the tension in the string becomes zero, but even when tension becomes zero, there's always a component of the bob's weight towards the center of the circle. Why then does the bob leave the circular trajectory? Do we know why there is a speed limit in our universe? This question is about why we have a universal speed limit (the speed of light in vacuum). Is there a more fundamental law that tells us why this is? I'm not asking why the speed limit is equal to $c$ and not something else, but why there is a limit at all. EDIT: Answers like &quot;if it was not..&quot; and answers explaining the consequences of having or not having a speed limit are not--in my opinion-- giving an answer to whether there is a more fundamental way to derive it from a law to explain this limit. The following happened playing Minesweeper:   How do I figure out which square to click? What is this agglomeration of pink cells I found attached to a stone?