I want to encrypt some small amount of data using ECDH for use by myself later, but I don't want to generate an ephemeral keypair like in ECIES, due to time and space constraints.  Would it be safe to use my existing EC keypair to encrypt data "for myself"?  In this case I don't need to store any key material with the ciphertext, which is nice.  But is it secure? Alternatively I could just hash my private key and use that as the symmetric key. Would that be more or less secure?    The encryption goes as follows. Let $P$ be my public point on the curve secp256k1 and let $P=[d]G$ hold with $d$ being my private key. I encrypt a message $m$ as follows:   I perform an ECDH agreement with my own public key, i.e. compute $S=[d]P$ I hash the common point with SHA256 to get the key $K=H(S)$ I generate a 16 byte IV uniformly at random using a CSPRNG: $IV\xleftarrow{\$}\{0,1\}^{128}$ I encrypt the message using AES-256-CBC as $c=E_{K,IV}(m)$ I return $(IV,c)$, knowing that I can re-derive $K$ using only my key-pair
I am using ECIES (Cryptobox as poncho pointed out) for public key encryption with ECC between Alice and Bob with secret/public keys $(a,A)$ and $(b,B)$ respectively. So Alice encrypts to Bob with  $$ Encrypt(aB,Message) $$  Additionally I would like to encrypt some of Alice's data such that only she can decrypt it. Is it safe to use ECIES to compute a shared secret from Alice's secret and public key as in  $$ Encrypt(aA,Message) $$  I know I could randomly generate a public key, but then I would have to store this key somewhere which I would like to avoid.
ODBC and ADO connection to SQL Server: What protocol is used when connecting to \? It used to be that the new, super wide, touch friendly context menu style that Google introduced a few versions of Chrome ago could be turned off using the start up flag "--disable-new-menu-style".  As of Chrome 28, this is no longer the case, and as a desktop user it is very irritating to see menus that previously fit in the screen not to do so anymore — I don't think I can get used to it. Is there any way around it? If the flag is gone for good, can the style of the context menus be perhaps edited with custom css like the web inspector? Inline suggested edit reviews are truncated in medium-width windows What is the minimal set of parts for a circut with this AVR microcontroller? My Arduino Uno has a ATMEGA328P-PU microcontroller, and bunch of other stuff on the board. I'd like to program the chip without the Arduino software, and only the minimum of other components.  I want to eventually create things without the cost of Arduino, and I want to learn about the other parts on the board and add them back as as needed.  I'm comfortable with C and gcc, so I can probably figure out the software part. But what, if anything, besides these two products below, do I need to have in the breadboard with the microcontroller? Appearing on the second page (under the section Digression: Size worries) of the following paper about the Yoneda Lemma:     It says that $a$ $priori$ $[\mathcal C^{op},Set](H_A,X))$ is a class. I don't understand why this is the case.  My understanding is that $a$ $priori$ each member of $[\mathcal C^{op},Set](H_A,X))$ is a class.  So it seems to me that $[\mathcal C^{op},Set](H_A,X))$ could be a collection of proper classes.  I've looked at this , but it hasn't helped me much.  Any help is appreciated -Thanks How do I use filenames that start with a dash "-" as command arguments? Is there a word in English to qualify the highest-ranked student in a class in a year?  We are talking here about higher education, especially in the context of curricula that keep a given set of students over the course of several years, being ranked at the end of each year, possibly with competitive admission for the following year. The ranking is a weighted average of all marks obtained over the year.  I am looking for a single word, or expression, to quickly designate the one student with the highest ranking. If there is no such thing in English, then let's try to get the most concise and idiomatic definition.  In all cases, it is not emotionally connoted, i.e. not pejorative nor bragging.  For French speakers: I am looking for the translation of “major de promotion”.    EDIT: additional, not as much of a pure “word request” question: is this anything you should mention on a curriculum vitæ in the English-speaking world? If so, please mention whether the given word is appropriate for such a use&nbsp;&nbsp;:) I have not been able to watch CBS all access for some time now. Error 2004. I have not found another browser for ubuntu that will play all access either. However firefox for windows plays it fine? Is there a fix in the works for ubuntu firefox? How to create a bootable USB stick? I am looking at this:    I need to create a boot disk to test Ubuntu to make sure it will run on a PC (Compaq Mini CQ10-120LA) I was given. I can create the boot disk off of a Mac (in English) or Windows (but Windows is in Spanish and foreign to me).   Questions:     What format do I choose for the USB stick? (I wish the instructions stated this). What is Dash? (Will I know when I run the installer?) Can I do this from a Mac or Windows computer? Or only from Ubuntu? Export File Dialog in Blender 2.80 How can I get bring up a popup file browser in Blender 2.80 invoked by a button click in my addon, to define the name and location of a file to be exported?  In Blender 2.7x, I did this via the context window manager in the invoke function, but it is very possible that this hasn't been the preferred method for years, as I'm not finding useful documentation when I search for how to update this.  class MYTOOL_OT_write_data(bpy.types.Operator):     bl_idname = "mytool.write_data"     bl_label = "Write data file"      directory: bpy.props.StringProperty(subtype="FILE_PATH")     filename: bpy.props.StringProperty(subtype="FILE_NAME")      def invoke(self, context, event):  # 2.7x method         WindowManager = context.window_manager         context.window_manager.FILEBROWSERect_add(self)  # &lt;-- error here         return{"RUNNING_MODAL"}      def execute(self, context):         directory = self.directory         filename = self.filename         # Write csv data file using normal python functionality         return{'FINISHED'}   In Blender 2.80, I am getting the error "AttributeError: 'WindowManager' object has no attribute 'FILEBROWSERect_add'".  Thanks for your help.    UPDATED SOLUTION based on brockmann's solution below.  The trick is to use the ExportHelper util (which existed long before Blender 2.80):  from bpy_extras.io_utils import ExportHelper  class MYTOOL_OT_write_data(bpy.types.Operator, ExportHelper):     bl_idname = "mytool.write_data"     bl_label = "Write data file"      filename_ext = ".csv"  # ExportHelper mixin class uses this     def execute(self, context):         filepath = self.filepath         # f = open(filepath, 'w')         # f.write(stuff)         # f.close()         return{'FINISHED'} Where is the known_hosts file for OpenSSH for Windows? Is there any way to make a method with more than one instance? Unable to change payment information to NONE in iOS Appstore If Chrome is already open, it opens new sites (e.g. from Windows shortcuts, application shortcuts, or from the Run dialog) in new tabs of the existing instance.   I'd prefer to open new sites in a separate window (a new instance of Chrome).   I don't see that in the options - is it possible? How to scale dimensions proportionally to a specific size? I modeled a man and would like to scale him down to be exactly 6' tall (Z dimension), however I cannot find a way to do that. I know I can go to front ortho view and and use the normal scale S  key to scale it, however that requires some pretty specific fine tuning in order to get it to the right dimensions.  I'd like to be able to essentially type "6" into the Z dimension (don't worry I have it setup in imperial) and have it scale the X and Y dimensions proportionally. Dimensionality of null space when Trace is Zero This is the fourth part of a four-part problem in Charles W. Curtis's book entitled Linear Algebra, An Introductory Approach (p. 216).  I've succeeded in proving the first three parts, but the most interesting part of the problem eludes me.  Part (a) requires the reader to prove that $\operatorname{Tr}{(AB)} = \operatorname{Tr}{(BA)}$, which I was able to show by writing out each side of the equation using sigma notation.  Part (b) asks the reader to use part (a) to show that similar matrices have the same trace.  If $A$ and $B$ are similar, then  $\operatorname{Tr}{(A)} = \operatorname{Tr}{(S^{-1}BS)}$  $= \operatorname{Tr}(BSS^{-1})$  $= \operatorname{Tr}(B)$,  which completes part (b).  Part (c) asks the reader to show that the vector subspace of matrices with trace equal to zero have dimension $n^2 - 1$.  Curtis provides the hint that the map from $M_n(F)$ to $F$ is a linear transformation.  From this, I used the theorem that $\dim T(V) + \dim n(T) = \dim V$ to obtain the dimension of the null space.  Part (d), however, I'm stuck on.  It asks the reader to show that subspace described in part (c) is generated by matrices of the form $AB - BA$, where $A$ and $B$ are arbitrary $n \times n$ matrices.  I tried to form a basis for the subspace, but wasn't really sure what it would look like since an $n \times n$ matrix has $n^2$ entries in it, but the basis would need $n^2 - 1$ matrixes.  I also tried to think of a linear transformation whose image would have the form of $AB - BA$, but this also didn't help me.  I'm kind of stuck...  Many thanks in advance! Add warning when changing display name Deriving Chinese Remainder Theorem from gcd Bezout identity My computer boots to a black screen, what options do I have to fix it? Most efficient way of booking academic supervision appointments I'm wondering if there's a more efficient method of booking an academic supervision appointment. The method I experienced was a schedule on the professor's door, first-come-first-serve.   How do we employ technology that is the most efficient (reduces scheduling time, permitting all students to view sign ups)?