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  • About shared (static) Members and its behavior

    - by Allende
    I just realized that I can access shared members from instances of classes (probably this is not correct, but compile and run), and also learn/discover that, I can modify shared members, then create a new instance and access the new value of the shared member. My question is, what happens to the shared members, when it comes back to the "default" value (class declaration), how dangerous is it do this ? is it totally bad ? is it valid in some cases ?. If you want to test my point here is the code (console project vb.net) that I used to test shared members, as you can see/compile/run, the shared member "x" of the class "Hello" has default value string "Default", but at runtime it changes it, and after creating a new object of that class, this object has the new value of the shared member. Module Module1 Public Class hello Public Shared x As String = "Default" Public Sub New() End Sub End Class Sub Main() Console.WriteLine("hello.x=" & hello.x) Dim obj As New hello() Console.WriteLine("obj.x=" & obj.x) obj.x = "Default shared memeber, modified in object" Console.WriteLine("obj.x=" & obj.x) hello.x = "Defaul shared member, modified in class" Console.WriteLine("hello.x=" & hello.x) Dim obj2 As New hello() Console.WriteLine("obj2.x=" & obj2.x) Console.ReadLine() End Sub End Module UPDATE: First at all, thanks to everyone, each answer give feedback, I suppose, by respect I should choose one as "the answer", I don't want to be offensive to anyone, so please don't take it so bad if I didn't choose you answer.

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  • Empty interface to combine multiple interfaces

    - by user1109519
    Suppose you have two interfaces: interface Readable { public void read(); } interface Writable { public void write(); } In some cases the implementing objects can only support one of these but in a lot of cases the implementations will support both interfaces. The people who use the interfaces will have to do something like: // can't write to it without explicit casting Readable myObject = new MyObject(); // can't read from it without explicit casting Writable myObject = new MyObject(); // tight coupling to actual implementation MyObject myObject = new MyObject(); None of these options is terribly convenient, even more so when considering that you want this as a method parameter. One solution would be to declare a wrapping interface: interface TheWholeShabam extends Readable, Writable {} But this has one specific problem: all implementations that support both Readable and Writable have to implement TheWholeShabam if they want to be compatible with people using the interface. Even though it offers nothing apart from the guaranteed presence of both interfaces. Is there a clean solution to this problem or should I go for the wrapper interface? UPDATE It is in fact often necessary to have an object that is both readable and writable so simply seperating the concerns in the arguments is not always a clean solution. UPDATE2 (extracted as answer so it's easier to comment on) UPDATE3 Please beware that the primary usecase for this is not streams (although they too must be supported). Streams make a very specific distinction between input and output and there is a clear separation of responsibilities. Rather, think of something like a bytebuffer where you need one object you can write to and read from, one object that has a very specific state attached to it. These objects exist because they are very useful for some things like asynchronous I/O, encodings,...

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  • An ideal way to decode JSON documents in C?

    - by AzizAG
    Assuming I have an API to consume that uses JSON as a data transmission method, what is an ideal way to decode the JSON returned by each API resource? For example, in Java I'd create a class for each API resource then initiate an object of that class and consume data from it. for example: class UserJson extends JsonParser { public function UserJson(String document) { /*Initial document parsing goes here...*/ } //A bunch of getter methods . . . . } The probably do something like this: UserJson userJson = new UserJson(jsonString);//Initial parsing goes in the constructor String username = userJson.getName();//Parse JSON name property then return it as a String. Or when using a programming language with associative arrays(i.e., hash table) the decoding process doesn't require creating a class: (PHP) $userJson = json_decode($jsonString);//Decode JSON as key=>value $username = $userJson['name']; But, when I'm programming in procedural programming languages (C), I can't go with either method, since C is neither OOP nor supports associative arrays(by default, at least). What is the "correct" method of parsing pre-defined JSON strings(i.e., JSON documents specified by the API provider via examples or documentation)? The method I'm currently using is creating a file for each API resource to parse, the problem with this method is that it's basically a lousy version of the OOP method, as it looks exactly like the OOP method but doesn't provide any OOP benefits(e.g., can't pass an object of the parser, etc.). I've been thinking about encapsulating each API resource parser file in a publicly accessed structure(pointing all functions/publicly usable variables to the structure) then accessing the parser file code from within the structure(parser.parse(), parser.getName(), etc.). As this way looks a bit better than the my current method, it still just a rip off the OOP way, isn't it? Any suggestions for methods to parse JSON documents on procedural programming lanauges? Any comments on the methods I'm currently using(either 3 of them)?

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  • design for supporting entities with images

    - by brainydexter
    I have multiple entities like Hotels, Destination Cities etc which can contain images. The way I have my system setup right now is, I think of all the images belonging to this universal set (a table in the DB contains filePaths to all the images). When I have to add an image to an entity, I see if the entity exists in this universal set of images. If it exists, attach the reference to this image, else create a new image. E.g.: class ImageEntityHibernateDAO { public void addImageToEntity(IContainImage entity, String filePath, String title, String altText) { ImageEntity image = this.getImage(filePath); if (image == null) image = new ImageEntity(filePath, title, altText); getSession().beginTransaction(); entity.getImages().add(image); getSession().getTransaction().commit(); } } My question is: Earlier I had to write this code for each entity (and each entity would have a Set collection). So, instead of re-writing the same code, I created the following interface: public interface IContainImage { Set<ImageEntity> getImages(); } Entities which have image collections also implements IContainImage interface. Now, for any entity that needs to support adding Image functionality, all I have to invoke from the DAO looks something like this: // in DestinationDAO::addImageToDestination { imageDao.addImageToEntity(destination, imageFileName, imageTitle, imageAltText); // in HotelDAO::addImageToHotel { imageDao.addImageToEntity(hotel, imageFileName, imageTitle, imageAltText); It'd be great help if someone can provide me some critique on this design ? Are there any serious flaws that I'm not seeing right away ?

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  • Functional programming compared to OOP with classes

    - by luckysmack
    I have been interested in some of the concepts of functional programming lately. I have used OOP for some time now. I can see how I would build a fairly complex app in OOP. Each object would know how to do things that object does. Or anything it's parents class does as well. So I can simply tell Person().speak() to make the person talk. But how do I do similar things in functional programming? I see how functions are first class items. But that function only does one specific thing. Would I simply have a say() method floating around and call it with an equivalent of Person() argument so I know what kind of thing is saying something? So I can see the simple things, just how would I do the comparable of OOP and objects in functional programming, so I can modularize and organize my code base? For reference, my primary experience with OOP is Python, PHP, and some C#. The languages that I am looking at that have functional features are Scala and Haskell. Though I am leaning towards Scala. Basic Example (Python): Animal(object): def say(self, what): print(what) Dog(Animal): def say(self, what): super().say('dog barks: {0}'.format(what)) Cat(Animal): def say(self, what): super().say('cat meows: {0}'.format(what)) dog = Dog() cat = Cat() dog.say('ruff') cat.say('purr')

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  • A few questions about how JavaScript works

    - by KayoticSully
    I originally posted on Stack Overflow and was told I might get some better answers here. I have been looking deeply into JavaScript lately to fully understand the language and have a few nagging questions that I can not seem to find answers to (Specifically dealing with Object Oriented programming. I know JavaScript is meant to be used in an OOP manner I just want to understand it for the sake of completeness). Assuming the following code: function TestObject() { this.fA = function() { // do stuff } this.fB = testB; function testB() { // do stuff } } TestObject.prototype = { fC : function { // do stuff } } What is the difference between functions fA and fB? Do they behave exactly the same in scope and potential ability? Is it just convention or is one way technically better or proper? If there is only ever going to be one instance of an object at any given time, would adding a function to the prototype such as fC even be worthwhile? Is there any benefit to doing so? Is the prototype only really useful when dealing with many instances of an object or inheritance? And what is technically the "proper" way to add methods to the prototype the way I have above or calling TestObject.prototype.functionName = function(){} every time? I am looking to keep my JavaScript code as clean and readable as possible but am also very interested in what the proper conventions for Objects are in the language. I come from a Java and PHP background and am trying to not make any assumptions about how JavaScript works since I know it is very different being prototype based. Also are there any definitive JavaScript style guides or documentation about how JavaScript operates at a low level? Thanks!

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  • How would you model an objects representing different phases of an entity life cycle?

    - by Ophir Yoktan
    I believe the scenario is common mostly in business workflows - for example: loan management the process starts with a loan application, then there's the loan offer, the 'live' loan, and maybe also finished loans. all these objects are related, and share many fields all these objects have also many fields that are unique for each entity the variety of objects maybe large, and the transformation between the may not be linear (for example: a single loan application may end up as several loans of different types) How would you model this? some options: an entity for each type, each containing the relevant fields (possibly grouping related fields as sub entities) - leads to duplication of data. an entity for each object, but instead of duplicating data, each object has a reference to it's predecessor (the loan doesn't contain the loaner details, but a reference to the loan application) - this causes coupling between the object structure, and the way it was created. if we change the loan application, it shouldn't effect the structure of the loan entity. one large entity, with fields for the whole life cycle - this can create 'mega objects' with many fields. it also doesn't work well when there's a one to many or many to many relation between the phases.

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  • What OO Design to use ( is there a Design Pattern )?

    - by Blundell
    I have two objects that represent a 'Bar/Club' ( a place where you drink/socialise). In one scenario I need the bar name, address, distance, slogon In another scenario I need the bar name, address, website url, logo So I've got two objects representing the same thing but with different fields. I like to use immutable objects, so all the fields are set from the constructor. One option is to have two constructors and null the other fields i.e: class Bar { private final String name; private final Distance distance; private final Url url; public Bar(String name, Distance distance){ this.name = name; this.distance = distance; this.url = null; } public Bar(String name, Url url){ this.name = name; this.distance = null; this.url = url; } // getters } I don't like this as you would have to null check when you use the getters In my real example the first scenario has 3 fields and the second scenario has about 10, so it would be a real pain having two constructors, the amount of fields I would have to declare null and then when the object are in use you wouldn't know which Bar you where using and so what fields would be null and what wouldn't. What other options do I have? Two classes called BarPreview and Bar? Some type of inheritance / interface? Something else that is awesome?

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  • Ubuntu Preseed set Norwegian Keyboard?

    - by Vangelis Tasoulas
    It's been a couple of days now that I am trying to make a fully automated unattended installation. I managed to make it work with Ubuntu/Cobbler and a preseed file, but I cannot set the correct keyboard layout which is Norwegian in this case. I am doing the tests on a virtual machine and when I am going with a normal manual installation (no preseed) everything is working fine. When I am using the preseed file, I always end up with an "English (US)" keyboard no matter the many different options I have tried. I can change it manually with the "dpkg-reconfigure keyboard-configuration" command, but that's not the case. It should be handled automatically using the preseed file. I am using DEBCONF_DEBUG=5 when the grub is loading, and as I see in "/var/log/installer/syslog" file after the installation has finished, the preseeding commands are accepted. Can anyone help on this? The preseed file I am using is following: d-i debian-installer/country string NO d-i debian-installer/language string en_US:en d-i debian-installer/locale string en_US.UTF-8 d-i console-setup/ask_detect boolean false d-i keyboard-configuration/layout select Norwegian d-i keyboard-configuration/variant select Norwegian d-i keyboard-configuration/modelcode string pc105 d-i keyboard-configuration/layoutcode string no d-i keyboard-configuration/xkb-keymap select no d-i netcfg/choose_interface select auto d-i netcfg/get_hostname string myhostname d-i netcfg/get_domain string simula.no d-i hw-detect/load_firmware boolean true d-i mirror/country string manual d-i mirror/http/hostname string ftp.uninett.no d-i mirror/http/directory string /ubuntu d-i mirror/http/proxy string http://10.0.1.253:3142/ d-i mirror/codename string precise d-i mirror/suite string precise d-i clock-setup/utc boolean true d-i time/zone string Europe/Oslo d-i clock-setup/ntp boolean true d-i clock-setup/ntp-server string 10.0.1.254 d-i partman-auto/method string lvm partman-auto-lvm partman-auto-lvm/new_vg_name string vg0 d-i partman-auto/purge_lvm_from_device boolean true d-i partman-lvm/device_remove_lvm boolean true d-i partman-md/device_remove_md boolean true d-i partman-lvm/confirm boolean true d-i partman-lvm/confirm_nooverwrite boolean true d-i partman-auto-lvm/guided_size string max d-i partman-auto/choose_recipe select 30atomic d-i partman/default_filesystem string ext4 d-i partman-partitioning/confirm_write_new_label boolean true d-i partman/choose_partition select finish d-i partman/confirm boolean true d-i partman/confirm_nooverwrite boolean true d-i partman/mount_style select uuid d-i passwd/root-login boolean false d-i passwd/make-user boolean true d-i passwd/user-fullname string vangelis d-i passwd/username string vangelis d-i passwd/user-password-crypted password $6$asdafdsdfasdfasdf d-i passwd/user-uid string d-i user-setup/allow-password-weak boolean false d-i passwd/user-default-groups string adm cdrom dialout lpadmin plugdev sambashare d-i user-setup/encrypt-home boolean false d-i apt-setup/restricted boolean true d-i apt-setup/universe boolean true d-i apt-setup/backports boolean true d-i apt-setup/services-select multiselect security d-i apt-setup/security_host string security.ubuntu.com d-i apt-setup/security_path string /ubuntu tasksel tasksel/first multiselect Basic Ubuntu server, OpenSSH server d-i pkgsel/include string build-essential htop vim nmap ntp d-i pkgsel/upgrade select safe-upgrade d-i pkgsel/update-policy select none d-i pkgsel/updatedb boolean true d-i grub-installer/only_debian boolean true d-i grub-installer/with_other_os boolean true d-i finish-install/keep-consoles boolean false d-i finish-install/reboot_in_progress note d-i cdrom-detect/eject boolean true d-i debian-installer/exit/halt boolean false d-i debian-installer/exit/poweroff boolean false

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  • String contains trailing zeroes when converted from decimal [migrated]

    - by Locke
    I've run into an unusual quirk in a program I'm writing, and I was trying to figure out if anyone knew the cause. Note that fixing the issue is easy enough. I just can't figure out why it is happening in the first place. I have a WinForms program written in VB.NET that is displaying a subset of data. It contains a few labels that show numeric values (the .Text property of the labels are being assigned directly from the Decimal values). These numbers are being returned by a DLL I wrote in C#. The DLL calls a webservice which initially returns the values in question. It returns one as a string, the other as a decimal (I don't have any control over the webservice, I just consume it). The DLL assigns these to properties on an object (both of which are decimals) then returns that object back to the WinForm program that called the DLL. Obviously, there's a lot of other data being consumed from the webservice, but no other operations are happening which could modify these properties. So, the short version is: WinForm requests a new Foo from the DLL. DLL creates object Foo. DLL calls webservice, which returns SomeOtherFoo. //Both Foo.Bar1 and Foo.Bar2 are decimals Foo.Bar1 = decimal.Parse(SomeOtherFoo.Bar1); //SomeOtherFoo.Bar1 is a string equal to "2.9000" Foo.Bar2 = SomeOtherFoo.Bar2; //SomeOtherFoo.Bar2 is a decimal equal to 2.9D DLL returns Foo to WinForm. WinForm.lblMockLabelName1.Text = Foo.Bar1 //Inspecting Foo.Bar1 indicates my value is 2.9D WinForm.lblMockLabelName2.Text = Foo.Bar2 //Inspecting Foo.Bar2 also indicates I'm 2.9D So, what's the quirk? WinForm.lblMockLabelName1.Text displays as "2.9000", whereas WinForm.lblMockLabelname2.Text displays as "2.9". Now, everything I know about C# and VB indicates that the format of the string which was initially parsed into the decimal should have no bearing on the outcome of a later decimal.ToString() operation called on the same decimal. I would expect that decimal.Parse(someDecimalString).ToString() would return the string without any trailing zeroes. Everything I find online seems to corroborate this (there are countless Stack Overflow questions asking exactly the opposite...how to keep the formatting from the initial parsing). At the moment, I've just removed the trailing zeroes from the initial string that gets parsed, which has hidden the quirk. However, I'd love to know why it happens in the first place.

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  • Creating an object that is ready to be used & unset properties - with IoC

    - by GetFuzzy
    I have a question regarding the specifics of object creation and the usage of properties. A best practice is to put all the properties into a state such that the object is useful when its created. Object constructors help ensure that required dependencies are created. I've found myself following a pattern lately, and then questioning its appropriateness. The pattern looks like this... public class ThingProcesser { public List<Thing> CalculatedThings { get; set; } public ThingProcesser() { CalculatedThings = new List<Thing>(); } public double FindCertainThing() { CheckForException(); foreach (var thing in CalculatedThings) { //do some stuff with things... } } public double FindOtherThing() { CheckForException(); foreach (var thing in CalculatedThings) { //do some stuff with things... } } private void CheckForException() { if (CalculatedThings.Count < 2) throw new InvalidOperationException("Calculated things must have more than 2 items"); } } The list of items is not being changed, just looked through by the methods. There are several methods on the class, and to avoid having to pass the list of things to each function as a method parameter, I set it once on the class. While this works, does it violate the principle of least astonishment? Since starting to use IoC I find myself not sticking things into the constructor, to avoid having to use a factory pattern. For example, I can argue with myself and say well the ThingProcessor really needs a List to work, so the object should be constructed like this. public class ThingProcesser { public List<Thing> CalculatedThings { get; set; } public ThingProcesser(List<Thing> calculatedThings) { CalculatedThings = calculatedThings; } } However, if I did this, it would complicate things for IoC, and this scenario hardly seems appropriate for something like the factory pattern. So in summary, are there some good guidelines for when something should be part of the object state, vs. passed as a method parameter? When using IoC, is the factory pattern the best way to deal with objects that need created with state? If something has to be passed to multiple methods in a class, does that render it a good candidate to be part of the objects state?

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  • What is a good java data structure for storing nested items (like cities in states)?

    - by anotherAlan
    I'm just getting started in Java and am looking for advice on a good way to store nested sets of data. For example, I'm interested in storing city population data that can be accessed by looking up the city in a given state. (Note: eventually, other data will be stored with each city as well, this is just the first attempt at getting started.) The current approach I'm using is to have a StateList Object which contains a HashMap that stores State Objects via a string key (i.e. HashMap<String, State>). Each State Object contains its own HashMap of City Objects keyed off the city name (i.e. HashMap<String, City>). A cut down version of what I've come up with looks like this: // TestPopulation.java public class TestPopulation { public static void main(String [] args) { // build the stateList Object StateList sl = new StateList(); // get a test state State stateAl = sl.getState("AL"); // make sure it's there. if(stateAl != null) { // add a city stateAl.addCity("Abbeville"); // now grab the city City cityAbbevilleAl = stateAl.getCity("Abbeville"); cityAbbevilleAl.setPopulation(2987); System.out.print("The city has a pop of: "); System.out.println(Integer.toString(cityAbbevilleAl.getPopulation())); } // otherwise, print an error else { System.out.println("That was an invalid state"); } } } // StateList.java import java.util.*; public class StateList { // define hash map to hold the states private HashMap<String, State> theStates = new HashMap<String, State>(); // setup constructor that loads the states public StateList() { String[] stateCodes = {"AL","AK","AZ","AR","CA","CO"}; // etc... for (String s : stateCodes) { State newState = new State(s); theStates.put(s, newState); } } // define method for getting a state public State getState(String stateCode) { if(theStates.containsKey(stateCode)) { return theStates.get(stateCode); } else { return null; } } } // State.java import java.util.*; public class State { // Setup the state code String stateCode; // HashMap for cities HashMap<String, City> cities = new HashMap<String, City>(); // define the constructor public State(String newStateCode) { System.out.println("Creating State: " + newStateCode); stateCode = newStateCode; } // define the method for adding a city public void addCity(String newCityName) { City newCityObj = new City(newCityName); cities.put(newCityName, newCityObj); } // define the method for getting a city public City getCity(String cityName) { if(cities.containsKey(cityName)) { return cities.get(cityName); } else { return null; } } } // City.java public class City { // Define the instance vars String cityName; int cityPop; // setup the constructor public City(String newCityName) { cityName = newCityName; System.out.println("Created City: " + newCityName); } public void setPopulation(int newPop) { cityPop = newPop; } public int getPopulation() { return cityPop; } } This is working for me, but I'm wondering if there are gotchas that I haven't run into, or if there are alternate/better ways to do the same thing. (P.S. I know that I need to add some more error checking in, but right now, I'm focused on trying to figure out a good data structure.) (NOTE: Edited to change setPop() and getPop() to setPopulation() and getPopulation() respectively to avoid confucsion)

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  • Elfsign Object Signing on Solaris

    - by danx
    Elfsign Object Signing on Solaris Don't let this happen to you—use elfsign! Solaris elfsign(1) is a command that signs and verifies ELF format executables. That includes not just executable programs (such as ls or cp), but other ELF format files including libraries (such as libnvpair.so) and kernel modules (such as autofs). Elfsign has been available since Solaris 10 and ELF format files distributed with Solaris, since Solaris 10, are signed by either Sun Microsystems or its successor, Oracle Corporation. When an ELF file is signed, elfsign adds a new section the ELF file, .SUNW_signature, that contains a RSA public key signature and other information about the signer. That is, the algorithm used, algorithm OID, signer CN/OU, and time stamp. The signature section can later be verified by elfsign or other software by matching the signature in the file agains the ELF file contents (excluding the signature). ELF executable files may also be signed by a 3rd-party or by the customer. This is useful for verifying the origin and authenticity of executable files installed on a system. The 3rd-party or customer public key certificate should be installed in /etc/certs/ to allow verification by elfsign. For currently-released versions of Solaris, only cryptographic framework plugin libraries are verified by Solaris. However, all ELF files may be verified by the elfsign command at any time. Elfsign Algorithms Elfsign signatures are created by taking a digest of the ELF section contents, then signing the digest with RSA. To verify, one takes a digest of ELF file and compares with the expected digest that's computed from the signature and RSA public key. Originally elfsign took a MD5 digest of a SHA-1 digest of the ELF file sections, then signed the resulting digest with RSA. In Solaris 11.1 then Solaris 11.1 SRU 7 (5/2013), the elfsign crypto algorithms available have been expanded to keep up with evolving cryptography. The following table shows the available elfsign algorithms: Elfsign Algorithm Solaris Release Comments elfsign sign -F rsa_md5_sha1   S10, S11.0, S11.1 Default for S10. Not recommended* elfsign sign -F rsa_sha1 S11.1 Default for S11.1. Not recommended elfsign sign -F rsa_sha256 S11.1 patch SRU7+   Recommended ___ *Most or all CAs do not accept MD5 CSRs and do not issue MD5 certs due to MD5 hash collision problems. RSA Key Length. I recommend using RSA-2048 key length with elfsign is RSA-2048 as the best balance between a long expected "life time", interoperability, and performance. RSA-2048 keys have an expected lifetime through 2030 (and probably beyond). For details, see Recommendation for Key Management: Part 1: General, NIST Publication SP 800-57 part 1 (rev. 3, 7/2012, PDF), tables 2 and 4 (pp. 64, 67). Step 1: create or obtain a key and cert The first step in using elfsign is to obtain a key and cert from a public Certificate Authority (CA), or create your own self-signed key and cert. I'll briefly explain both methods. Obtaining a Certificate from a CA To obtain a cert from a CA, such as Verisign, Thawte, or Go Daddy (to name a few random examples), you create a private key and a Certificate Signing Request (CSR) file and send it to the CA, following the instructions of the CA on their website. They send back a signed public key certificate. The public key cert, along with the private key you created is used by elfsign to sign an ELF file. The public key cert is distributed with the software and is used by elfsign to verify elfsign signatures in ELF files. You need to request a RSA "Class 3 public key certificate", which is used for servers and software signing. Elfsign uses RSA and we recommend RSA-2048 keys. The private key and CSR can be generated with openssl(1) or pktool(1) on Solaris. Here's a simple example that uses pktool to generate a private RSA_2048 key and a CSR for sending to a CA: $ pktool gencsr keystore=file format=pem outcsr=MYCSR.p10 \ subject="CN=canineswworks.com,OU=Canine SW object signing" \ outkey=MYPRIVATEKEY.key $ openssl rsa -noout -text -in MYPRIVATEKEY.key Private-Key: (2048 bit) modulus: 00:d2:ef:42:f2:0b:8c:96:9f:45:32:fc:fe:54:94: . . . [omitted for brevity] . . . c9:c7 publicExponent: 65537 (0x10001) privateExponent: 26:14:fc:49:26:bc:a3:14:ee:31:5e:6b:ac:69:83: . . . [omitted for brevity] . . . 81 prime1: 00:f6:b7:52:73:bc:26:57:26:c8:11:eb:6c:dc:cb: . . . [omitted for brevity] . . . bc:91:d0:40:d6:9d:ac:b5:69 prime2: 00:da:df:3f:56:b2:18:46:e1:89:5b:6c:f1:1a:41: . . . [omitted for brevity] . . . f3:b7:48:de:c3:d9:ce:af:af exponent1: 00:b9:a2:00:11:02:ed:9a:3f:9c:e4:16:ce:c7:67: . . . [omitted for brevity] . . . 55:50:25:70:d3:ca:b9:ab:99 exponent2: 00:c8:fc:f5:57:11:98:85:8e:9a:ea:1f:f2:8f:df: . . . [omitted for brevity] . . . 23:57:0e:4d:b2:a0:12:d2:f5 coefficient: 2f:60:21:cd:dc:52:76:67:1a:d8:75:3e:7f:b0:64: . . . [omitted for brevity] . . . 06:94:56:d8:9d:5c:8e:9b $ openssl req -noout -text -in MYCSR.p10 Certificate Request: Data: Version: 2 (0x2) Subject: OU=Canine SW object signing, CN=canineswworks.com Subject Public Key Info: Public Key Algorithm: rsaEncryption Public-Key: (2048 bit) Modulus: 00:d2:ef:42:f2:0b:8c:96:9f:45:32:fc:fe:54:94: . . . [omitted for brevity] . . . c9:c7 Exponent: 65537 (0x10001) Attributes: Signature Algorithm: sha1WithRSAEncryption b3:e8:30:5b:88:37:68:1c:26:6b:45:af:5e:de:ea:60:87:ea: . . . [omitted for brevity] . . . 06:f9:ed:b4 Secure storage of RSA private key. The private key needs to be protected if the key signing is used for production (as opposed to just testing). That is, protect the key to protect against unauthorized signatures by others. One method is to use a PIN-protected PKCS#11 keystore. The private key you generate should be stored in a secure manner, such as in a PKCS#11 keystore using pktool(1). Otherwise others can sign your signature. Other secure key storage mechanisms include a SCA-6000 crypto card, a USB thumb drive stored in a locked area, a dedicated server with restricted access, Oracle Key Manager (OKM), or some combination of these. I also recommend secure backup of the private key. Here's an example of generating a private key protected in the PKCS#11 keystore, and a CSR. $ pktool setpin # use if PIN not set yet Enter token passphrase: changeme Create new passphrase: Re-enter new passphrase: Passphrase changed. $ pktool gencsr keystore=pkcs11 label=MYPRIVATEKEY \ format=pem outcsr=MYCSR.p10 \ subject="CN=canineswworks.com,OU=Canine SW object signing" $ pktool list keystore=pkcs11 Enter PIN for Sun Software PKCS#11 softtoken: Found 1 asymmetric public keys. Key #1 - RSA public key: MYPRIVATEKEY Here's another example that uses openssl instead of pktool to generate a private key and CSR: $ openssl genrsa -out cert.key 2048 $ openssl req -new -key cert.key -out MYCSR.p10 Self-Signed Cert You can use openssl or pktool to create a private key and a self-signed public key certificate. A self-signed cert is useful for development, testing, and internal use. The private key created should be stored in a secure manner, as mentioned above. The following example creates a private key, MYSELFSIGNED.key, and a public key cert, MYSELFSIGNED.pem, using pktool and displays the contents with the openssl command. $ pktool gencert keystore=file format=pem serial=0xD06F00D lifetime=20-year \ keytype=rsa hash=sha256 outcert=MYSELFSIGNED.pem outkey=MYSELFSIGNED.key \ subject="O=Canine Software Works, OU=Self-signed CA, CN=canineswworks.com" $ pktool list keystore=file objtype=cert infile=MYSELFSIGNED.pem Found 1 certificates. 1. (X.509 certificate) Filename: MYSELFSIGNED.pem ID: c8:24:59:08:2b:ae:6e:5c:bc:26:bd:ef:0a:9c:54:de:dd:0f:60:46 Subject: O=Canine Software Works, OU=Self-signed CA, CN=canineswworks.com Issuer: O=Canine Software Works, OU=Self-signed CA, CN=canineswworks.com Not Before: Oct 17 23:18:00 2013 GMT Not After: Oct 12 23:18:00 2033 GMT Serial: 0xD06F00D0 Signature Algorithm: sha256WithRSAEncryption $ openssl x509 -noout -text -in MYSELFSIGNED.pem Certificate: Data: Version: 3 (0x2) Serial Number: 3496935632 (0xd06f00d0) Signature Algorithm: sha256WithRSAEncryption Issuer: O=Canine Software Works, OU=Self-signed CA, CN=canineswworks.com Validity Not Before: Oct 17 23:18:00 2013 GMT Not After : Oct 12 23:18:00 2033 GMT Subject: O=Canine Software Works, OU=Self-signed CA, CN=canineswworks.com Subject Public Key Info: Public Key Algorithm: rsaEncryption Public-Key: (2048 bit) Modulus: 00:bb:e8:11:21:d9:4b:88:53:8b:6c:5a:7a:38:8b: . . . [omitted for brevity] . . . bf:77 Exponent: 65537 (0x10001) Signature Algorithm: sha256WithRSAEncryption 9e:39:fe:c8:44:5c:87:2c:8f:f4:24:f6:0c:9a:2f:64:84:d1: . . . [omitted for brevity] . . . 5f:78:8e:e8 $ openssl rsa -noout -text -in MYSELFSIGNED.key Private-Key: (2048 bit) modulus: 00:bb:e8:11:21:d9:4b:88:53:8b:6c:5a:7a:38:8b: . . . [omitted for brevity] . . . bf:77 publicExponent: 65537 (0x10001) privateExponent: 0a:06:0f:23:e7:1b:88:62:2c:85:d3:2d:c1:e6:6e: . . . [omitted for brevity] . . . 9c:e1:e0:0a:52:77:29:4a:75:aa:02:d8:af:53:24: c1 prime1: 00:ea:12:02:bb:5a:0f:5a:d8:a9:95:b2:ba:30:15: . . . [omitted for brevity] . . . 5b:ca:9c:7c:19:48:77:1e:5d prime2: 00:cd:82:da:84:71:1d:18:52:cb:c6:4d:74:14:be: . . . [omitted for brevity] . . . 5f:db:d5:5e:47:89:a7:ef:e3 exponent1: 32:37:62:f6:a6:bf:9c:91:d6:f0:12:c3:f7:04:e9: . . . [omitted for brevity] . . . 97:3e:33:31:89:66:64:d1 exponent2: 00:88:a2:e8:90:47:f8:75:34:8f:41:50:3b:ce:93: . . . [omitted for brevity] . . . ff:74:d4:be:f3:47:45:bd:cb coefficient: 4d:7c:09:4c:34:73:c4:26:f0:58:f5:e1:45:3c:af: . . . [omitted for brevity] . . . af:01:5f:af:ad:6a:09:bf Step 2: Sign the ELF File object By now you should have your private key, and obtained, by hook or crook, a cert (either from a CA or use one you created (a self-signed cert). The next step is to sign one or more objects with your private key and cert. Here's a simple example that creates an object file, signs, verifies, and lists the contents of the ELF signature. $ echo '#include <stdio.h>\nint main(){printf("Hello\\n");}'>hello.c $ make hello cc -o hello hello.c $ elfsign verify -v -c MYSELFSIGNED.pem -e hello elfsign: no signature found in hello. $ elfsign sign -F rsa_sha256 -v -k MYSELFSIGNED.key -c MYSELFSIGNED.pem -e hello elfsign: hello signed successfully. format: rsa_sha256. signer: O=Canine Software Works, OU=Self-signed CA, CN=canineswworks.com. signed on: October 17, 2013 04:22:49 PM PDT. $ elfsign list -f format -e hello rsa_sha256 $ elfsign list -f signer -e hello O=Canine Software Works, OU=Self-signed CA, CN=canineswworks.com $ elfsign list -f time -e hello October 17, 2013 04:22:49 PM PDT $ elfsign verify -v -c MYSELFSIGNED.key -e hello elfsign: verification of hello failed. format: rsa_sha256. signer: O=Canine Software Works, OU=Self-signed CA, CN=canineswworks.com. signed on: October 17, 2013 04:22:49 PM PDT. Signing using the pkcs11 keystore To sign the ELF file using a private key in the secure pkcs11 keystore, replace "-K MYSELFSIGNED.key" in the "elfsign sign" command line with "-T MYPRIVATEKEY", where MYPRIVATKEY is the pkcs11 token label. Step 3: Install the cert and test on another system Just signing the object isn't enough. You need to copy or install the cert and the signed ELF file(s) on another system to test that the signature is OK. Your public key cert should be installed in /etc/certs. Use elfsign verify to verify the signature. Elfsign verify checks each cert in /etc/certs until it finds one that matches the elfsign signature in the file. If one isn't found, the verification fails. Here's an example: $ su Password: # rm /etc/certs/MYSELFSIGNED.key # cp MYSELFSIGNED.pem /etc/certs # exit $ elfsign verify -v hello elfsign: verification of hello passed. format: rsa_sha256. signer: O=Canine Software Works, OU=Self-signed CA, CN=canineswworks.com. signed on: October 17, 2013 04:24:20 PM PDT. After testing, package your cert along with your ELF object to allow elfsign verification after your cert and object are installed or copied. Under the Hood: elfsign verification Here's the steps taken to verify a ELF file signed with elfsign. The steps to sign the file are similar except the private key exponent is used instead of the public key exponent and the .SUNW_signature section is written to the ELF file instead of being read from the file. Generate a digest (SHA-256) of the ELF file sections. This digest uses all ELF sections loaded in memory, but excludes the ELF header, the .SUNW_signature section, and the symbol table Extract the RSA signature (RSA-2048) from the .SUNW_signature section Extract the RSA public key modulus and public key exponent (65537) from the public key cert Calculate the expected digest as follows:     signaturepublicKeyExponent % publicKeyModulus Strip the PKCS#1 padding (most significant bytes) from the above. The padding is 0x00, 0x01, 0xff, 0xff, . . ., 0xff, 0x00. If the actual digest == expected digest, the ELF file is verified (OK). Further Information elfsign(1), pktool(1), and openssl(1) man pages. "Signed Solaris 10 Binaries?" blog by Darren Moffat (2005) shows how to use elfsign. "Simple CLI based CA on Solaris" blog by Darren Moffat (2008) shows how to set up a simple CA for use with self-signed certificates. "How to Create a Certificate by Using the pktool gencert Command" System Administration Guide: Security Services (available at docs.oracle.com)

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  • Class design issue

    - by user2865206
    I'm new to OOP and a lot of times I become stumped in situations similar to this example: Task: Generate an XML document that contains information about a person. Assume the information is readily available in a database. Here is an example of the structure: <Person> <Name>John Doe</Name> <Age>21</Age> <Address> <Street>100 Main St.</Street> <City>Sylvania</City> <State>OH</State> </Address> <Relatives> <Parents> <Mother> <Name>Jane Doe</Name> </Mother> <Father> <Name>John Doe Sr.</Name> </Father> </Parents> <Siblings> <Brother> <Name>Jeff Doe</Name> </Brother> <Brother> <Name>Steven Doe</Name> </Brother> </Siblings> </Relatives> </Person> Ok lets create a class for each tag (ie: Person, Name, Age, Address) Lets assume each class is only responsible for itself and the elements directly contained Each class will know (have defined by default) the classes that are directly contained within them Each class will have a process() function that will add itself and its childeren to the XML document we are creating When a child is drawn, as in the previous line, we will have them call process() as well Now we are in a recursive loop where each object draws their childeren until all are drawn But what if only some of the tags need to be drawn, and the rest are optional? Some are optional based on if the data exists (if we have it, we must draw it), and some are optional based on the preferences of the user generating the document How do we make sure each object has the data it needs to draw itself and it's childeren? We can pass down a massive array through every object, but that seems shitty doesnt it? We could have each object query the database for it, but thats a lot of queries, and how does it know what it's query is? What if we want to get rid of a tag later? There is no way to reference them. I've been thinking about this for 20 hours now. I feel like I am misunderstanding a design principle or am just approaching this all wrong. How would you go about programming something like this? I suppose this problem could apply to any senario where there are classes that create other classes, but the classes created need information to run. How do I get the information to them in a way that doesn't seem fucky? Thanks for all of your time, this has been kicking my ass.

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  • Delphi - How do I split a string into an array of strings based on a delimiter?

    - by Ryan
    Hello all, I'm trying to find a Delphi function that will split an input string into an array of strings based on a delimiter. I've found a lot on Google, but all seem to have their own issues and I haven't been able to get any of them to work. I just need to split a string like: "word:doc,txt,docx" into an array based on ':'. The result would be ['word', 'doc,txt,docx']. Does anyone have a function that they know works? Thank you

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  • Can I use regular expressions with String.Replace in C#?

    - by Taz
    For example I have code below string txt="I have strings like West, and West; and west, and Western." I would like to replace the word west or West with some other word. But I would like not to replace West in Western. Can I use regular expression in string.replace? I used inputText.Replace("(\\sWest.\\s)",temp); It dos not work.

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  • Lifetime issue of IDisposable unmanaged resources in a complex object graph?

    - by stakx
    This question is about dealing with unmanaged resources (COM interop) and making sure there won't be any resource leaks. I'd appreciate feedback on whether I seem to do things the right way. Background: Let's say I've got two classes: A class LimitedComResource which is a wrapper around a COM object (received via some API). There can only be a limited number of those COM objects, therefore my class implements the IDisposable interface which will be responsible for releasing a COM object when it's no longer needed. Objects of another type ManagedObject are temporarily created to perform some work on a LimitedComResource. They are not IDisposable. To summarize the above in a diagram, my classes might look like this: +---------------+ +--------------------+ | ManagedObject | <>------> | LimitedComResource | +---------------+ +--------------------+ | o IDisposable (I'll provide example code for these two classes in just a moment.) Question: Since my temporary ManagedObject objects are not disposable, I obviously have no control over how long they'll be around. However, in the meantime I might have Disposed the LimitedComObject that a ManagedObject is referring to. How can I make sure that a ManagedObject won't access a LimitedComResource that's no longer there? +---------------+ +--------------------+ | managedObject | <>------> | (dead object) | +---------------+ +--------------------+ I've currently implemented this with a mix of weak references and a flag in LimitedResource which signals whether an object has already been disposed. Is there any better way? Example code (what I've currently got): LimitedComResource: class LimitedComResource : IDisposable { private readonly IUnknown comObject; // <-- set in constructor ... void Dispose(bool notFromFinalizer) { if (!this.isDisposed) { Marshal.FinalReleaseComObject(comObject); } this.isDisposed = true; } internal bool isDisposed = false; } ManagedObject: class ManagedObject { private readonly WeakReference limitedComResource; // <-- set in constructor ... public void DoSomeWork() { if (!limitedComResource.IsAlive()) { throw new ObjectDisposedException(); // ^^^^^^^^^^^^^^^^^^^^^^^ // is there a more suitable exception class? } var ur = (LimitedComResource)limitedComResource.Target; if (ur.isDisposed) { throw new ObjectDisposedException(); } ... // <-- do something sensible here! } }

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  • Provide a URI as a parameter for an ODBC or OleDB provider connection string?

    - by womp
    Is there any way of specifying a URI (rather than a physical path) as the "Data Source" parameter in an OleDB connection string, or the "Dbq" parameter in an ODBC connection string, such that the default ADO.Net providers will work with it? I've tried file://, and it's a no go, so I just wanted to confirm whether or not this is possible. I'm guessing not, but any confirmation or documentation links would be appreciated.

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  • How to define function in a string in Android?

    - by androidNoob
    I have an event handler that I want to be connected to a button through xml. Basically, I want to define it as a string in my xml file, then use the property inspector to select the name of the handler for my button (the "on Click" property). How do I define a call to the function in the string?

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  • What makes the availability of both primitive and object-wrapped values in JavaScript useful?

    - by Delan Azabani
    I wrote a blog post a while ago detailing how the availability of both primitive and object-wrapped value types in JavaScript (for things such as Number, String and Boolean) causes trouble, including but not limited to type-casting to a boolean (e.g. object-wrapped NaN, "" and false actually type-cast to true). My question is, with all this confusion and problems, is there any benefit to JavaScript having both types of values for the built-in classes?

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