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  • How can I turn a string of text into a BigInteger representation for use in an El Gamal cryptosystem

    - by angstrom91
    I'm playing with the El Gamal cryptosystem, and my goal is to be able to encipher and decipher long sequences of text. I have come up with a method that works for short sequences, but does not work for long sequences, and I cannot figure out why. El Gamal requires the plaintext to be an integer. I have turned my string into a byte[] using the .getBytes() method for Strings, and then created a BigInteger out of the byte[]. After encryption/decryption, I turn the BigInteger into a byte[] using the .toByteArray() method for BigIntegers, and then create a new String object from the byte[]. This works perfectly when i call ElGamalEncipher with strings up to 129 characters. With 130 or more characters, the output produced is garbled. Can someone suggest how to solve this issue? Is this an issue with my method of turning the string into a BigInteger? If so, is there a better way to turn my string of text into a BigInteger and back? Below is my encipher/decipher code. public static BigInteger[] ElGamalEncipher(String plaintext, BigInteger p, BigInteger g, BigInteger r) { // returns a BigInteger[] cipherText // cipherText[0] is c // cipherText[1] is d BigInteger[] cipherText = new BigInteger[2]; BigInteger pText = new BigInteger(plaintext.getBytes()); // 1: select a random integer k such that 1 <= k <= p-2 BigInteger k = new BigInteger(p.bitLength() - 2, sr); // 2: Compute c = g^k(mod p) BigInteger c = g.modPow(k, p); // 3: Compute d= P*r^k = P(g^a)^k(mod p) BigInteger d = pText.multiply(r.modPow(k, p)).mod(p); // C =(c,d) is the ciphertext cipherText[0] = c; cipherText[1] = d; return cipherText; } public static String ElGamalDecipher(BigInteger c, BigInteger d, BigInteger a, BigInteger p) { //returns the plaintext enciphered as (c,d) // 1: use the private key a to compute the least non-negative residue // of an inverse of (c^a)' (mod p) BigInteger z = c.modPow(a, p).modInverse(p); BigInteger P = z.multiply(d).mod(p); byte[] plainTextArray = P.toByteArray(); String output = null; try { output = new String(plainTextArray, "UTF8"); } catch (Exception e) { } return output; }

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  • inner class within Interface

    - by harigm
    is that possible to create a inner class within an interface? If yes, why do we create like that? Anyways we are not going to create any interface objects? Do they help in any Development process?

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  • Using Hibernate to do a query involving two tables

    - by Nathan Spears
    I'm inexperienced with sql in general, so using Hibernate is like looking for an answer before I know exactly what the question is. Please feel free to correct any misunderstandings I have. I am on a project where I have to use Hibernate. Most of what I am doing is pretty basic and I could copy and modify. Now I would like to do something different and I'm not sure how configuration and syntax need to come together. Let's say I have two tables. Table A has two (relevant) columns, user GUID and manager GUID. Obviously managers can have more than one user under them, so queries on manager can return more than one row. Additionally, a manager can be managing the same user on multiple projects, so the same user can be returned multiple times for the same manager query. Table B has two columns, user GUID and user full name. One-to-one mapping there. I want to do a query on manager GUID from Table A, group them by unique User GUID (so the same User isn't in the results twice), then return those users' full names from Table B. I could do this in sql without too much trouble but I want to use Hibernate so I don't have to parse the sql results by hand. That's one of the points of using Hibernate, isn't it? Right now I have Hibernate mappings that map each column in Table A to a field (well the get/set methods I guess) in a DAO object that I wrote just to hold that Table's data. I could also use the Hibernate DAOs I have to access each table separately and do each of the things I mentioned above in separate steps, but that would be less efficient (I assume) that doing one query. I wrote a Service object to hold the data that gets returned from the query (my example is simplified - I'm going to keep some other data from Table A and get multiple columns from Table B) but I'm at a loss for how to write a DAO that can do the join, or use the DAOs I have to do the join. FYI, here is a sample of my hibernate config file (simplified to match my example): <hibernate-mapping package="com.my.dao"> <class name="TableA" table="table_a"> <id name="pkIndex" column="pk_index" /> <property name="userGuid" column="user_guid" /> <property name="managerGuid" column="manager_guid" /> </class> </hibernate-mapping> So then I have a DAOImplementation class that does queries and returns lists like public List<TableA> findByHQL(String hql, Map<String, String> params) etc. I'm not sure how "best practice" that is either.

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  • Strage character encoding problem with Eclipse / Spring / Tomcat 6

    - by Czar
    Hi, I have been trying things all da but can't get a proper solution. My problem is: I am developing a Spring MVC based app in my local Tomcat. My MYSQl database has UTF-8 encoding set, all content in there displays properly when using phpMyAdmin. Also the output in LOG files using log4j in catalina.out works fine. My JSP pages are configured by <!-- encoding --> <%@ page contentType="text/html; charset=UTF-8" %> <%@ page pageEncoding="UTF-8" %> Also showing data on my JSP works fine. I can also send data from my Controller without any DB intereference using special chars, e.g. String str = "UTF-8 Test: Ä Ö Ü ß è é â"; logger.debug(str); mav.addObject("utftest", str); That displays correctly in log and on jsp page in browser. BUT: When having special chars directly in my JSP file, e.g. for text in headers, this does not work. FF and Google Chrome display strange chars but report the page to be UTF-8. When switching to Latin, the chars just get more and more strange. Same problem when showing text tokens from my messages.properties file, although Eclipse says when right-clicking that UTF-8 will be used. I am a little it lost and don't know where to check now. Summary: DB storage is fine DB output on JSP is fine Output on JSP directly form controller is fine even reading in form forms is fine .properties files and JSP text is not fine !!! Any ideas? I really appreciate and tips.

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  • Accessing super class function using subclass object

    - by bdhar
    I have an object for a subclass who is of it's superclass type. There is a overridden function in subclass which gets executed when called using the object. How to call the parent's function using the same object? Is there any way to achieve this? package supercall; public class Main { public static void main(String[] args) { SomeClass obj = new SubClass(); obj.go(); } } class SomeClass { SomeClass() { } public void go() { System.out.println("Someclass go"); } } class SubClass extends SomeClass { SubClass() { } @Override public void go() { System.out.println("Subclass go"); } } Consider the code above. Here it prints Subclass go . Instead I have to print Superclass go .

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  • JEditorPanes, Preferred Size, and printing HTML

    - by Ryan Elkins
    I'm trying to print some HTML directly, without displaying anything to the user. It works currently (somewhat) using a custom JEditorPane that implements Printable. The problem I'm having is that it always wants to use a preferred size of 582px x 560px. If I manually change the size using something like setSize(x,y) it will change the size of the pane, put the content renders at preferred size, not actual size (so it's still 582x560). I can scale it up to fit the page, but it's basically just an enlarged version where the images are all pixelated and the layout is wrong (based on the smaller window size). Inside the print method of my Printable JEditorPane I used this to try and get the size: javax.swing.JWindow wnd = new javax.swing.JWindow(); wnd.setContentPane(this); wnd.setSize(1024,1584); wnd.pack(); Dimension d = wnd.getPreferredSize(); With or without that setSize and/or pack methods on the JWindow the preferred size always comes back as 582x560. I do have control over the html that I'm trying to print but I'd rather not have to rewrite all of that to scale it down so it will print correctly at full size (when scaled up).

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  • FileFinder using SQL

    - by James Morgan
    I was thinking of working on a project while I have some free time and this one looks pretty nice: http://mindprod.com/project/filefinder.html One thing I'm wondering about is that will it really be much faster compared to the regular windows search if I use SQL? I'm planning to use MySQL since it's open source. Also, do I need to be good at databases for this? I have basic knowledge about relational databases and can definitely make some SQL statements. Thanks.

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  • get cells odf a JTable

    - by tuxou
    hi how to display a row of a jtable in a from of JTextField when click on the row, ( I need this to edit the data base from the JTable ) My table model static class TableDataModel extends AbstractTableModel { private List nomColonnes; private List tableau; public TableDataModel(List nomColonnes, List tableau){ this.nomColonnes = nomColonnes; majDonnees(tableau); } public void majDonnees(List nouvellesDonnees){ this.tableau = nouvellesDonnees; fireTableDataChanged(); } public int getRowCount(){ return tableau.size(); } public int getColumnCount(){ return nomColonnes.size(); } public Object getValueAt(int row, int col){ return ((ArrayList)( tableau.get(row))).get(col); } public String getColumnName(int col){ return nomColonnes.get(col).toString(); } public Class getColumnClass(int c) { return getValueAt(0,c).getClass(); } public boolean isCellEditable(int row, int col){ return true; } public void setValueAt(Object value, int row, int col) { ((List)tableau.get(row)).set(col,value); fireTableCellUpdated(row, col); //i suppose i should update the database here } }

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  • JButton Layout Issue

    - by Tom Johnson
    I'm putting together the basic layout for a contacts book, and I want to know how I can make the 3 test buttons span from edge to edge just as the arrow buttons do. private static class ButtonHandler implements ActionListener { public void actionPerformed(ActionEvent e) { System.out.println("Code Placeholder"); } } public static void main(String[] args) { //down button ImageIcon downArrow = new ImageIcon("down.png"); JButton downButton = new JButton(downArrow); ButtonHandler downListener = new ButtonHandler(); downButton.addActionListener(downListener); //up button ImageIcon upArrow = new ImageIcon("up.png"); JButton upButton = new JButton(upArrow); ButtonHandler upListener = new ButtonHandler(); upButton.addActionListener(upListener); //contacts JButton test1Button = new JButton("Code Placeholder"); JButton test2Button = new JButton("Code Placeholder"); JButton test3Button = new JButton("Code Placeholder"); Box box = Box.createVerticalBox(); box.add(test1Button); box.add(test2Button); box.add(test3Button); JPanel content = new JPanel(); content.setLayout(new BorderLayout()); content.add(box, BorderLayout.CENTER); content.add(downButton, BorderLayout.SOUTH); content.add(upButton, BorderLayout.NORTH); JFrame window = new JFrame("Contacts"); window.setContentPane(content); window.setSize(400, 600); window.setLocation(100, 100); window.setVisible(true); }

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  • Creating multiple log files of different content with log4j

    - by Daniel
    Is there a way to configure log4j so that it outputs different levels of logging to different appenders? I'm trying to set up multiple log files. The main log file would catch all INFO and above messages for all classes. (In development, it would catch all DEBUG and above messages, and TRACE for specific classes.) Then, I would like to have a separate log file. That log file would catch all DEBUG messages for a specific subset of classes, and ignore all messages for any other class. Is there a way to get what I'm after? Thanks, Dan

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  • Create javadoc with multiple src dirs

    - by Ed Marty
    I have a Util package with source files in three seperate directories, defined like so: src/com/domain/util src/Standard/com/domain/util src/Extended/com/domain/util The package is built with the first set of files and either one of the second or third set, to create a total of two different implementations of the same interface. Now, I want to generate javadoc based on those files. How can I specify that? What I really want to do is javadoc com.domain.util -sourcepath ./src;./src/Standard to build the javadoc for the standard util package, and javadoc com.domain.util -sourcepath ./src;./src/Extended to build the javadoc for the extended util package. This doesn't work. The only way I've found so far to actually make it work is to merge the directory structure of the common classes and the Standard classes into another location and run with that for the standard javadoc, then do the same for the Extended package. Is there another way?

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  • Trouble getting started with Spring Roo and GWT

    - by Abdel Olakara
    Hi all, I am trying to get started with SpringRoo and GWT after seeing the keynote.. unfortunately I am stuck at this issue. I successfully created the project using Roo and added the persistence, the entities and when I perform the command "perform package" I get this error: 23/5/10 12:10:13 AM AST: [ERROR] ApplicationEntityTypesProcessor cannot be resolved 23/5/10 12:10:13 AM AST: [ERROR] ApplicationEntityTypesProcessor cannot be resolved to a type 23/5/10 12:10:13 AM AST: [WARN] advice defined in org.springframework.mock.staticmock.AnnotationDrivenStaticEntityMockingControl has not been applied [Xlint:adviceDidNotMatch] 23/5/10 12:10:13 AM AST: [WARN] advice defined in org.springframework.mock.staticmock.AbstractMethodMockingControl has not been applied [Xlint:adviceDidNotMatch] 23/5/10 12:10:13 AM AST: Build errors for helloroo; org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.codehaus.mojo:aspectj-maven-plugin:1.0:compile (default) on project helloroo: Compiler errors : error at import tp.gwt.request.ApplicationEntityTypesProcessor; I see this in the Maven console and cannot complete the build..I know there is some jar missing but how and why? because I downloaded all the latest version including GWT milestone release. Any idea why this error is occurring? How do I resolve this issue? Thanks in Advance, Abdel Olakara

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  • Wicket: Relative to absolute URL or get base URL

    - by Gilean
    If I have a relative path to a static asset (flash/blah.swf), what is the best way to convert this to an absolute URL (http://localhost/app/flash/blah.swf)? Or what is the best way to get the base URL of the Wicket application? I've tried using RequestUtils.toAbsolutePath but it doesn't seem to work reliably and is frequently throwing exceptions.

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  • how to achieve xxx.blogspot.com URL pattern ??

    - by abc
    Consider the case of blogspot.com the domain is the one blogspot.com only but suppose i register in it with xxx then i will have xxx.blogspot.com like wise here it won't be the subdomain (i can smell) , but its some thing different ... how to achieve this ?? in j2ee web application..

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  • IVR-style dialog system

    - by unbeli
    I need to build a dialog system similar to IVR used in call centers. My system is not phone-based, but the dialog is similar. Something like System: "Main menu: Enter [1] for menu1, [2] for menu2" User: [1] System: "menu1: enter [1] for apples, [2] for oranges, [3] for main menu" User: [7] System: "What??" System: "menu1: enter [1] for apples, [2] for oranges, [3] for main menu" User: [2] ... and so on I want to have a nice declarative description of all the possible options and a nice way to run through that tree, guided by user input. Already considered: ANTLR-generated lexer/parser (seems to be an overkill), SCXML-based state machine (seems like only transitions can be declared, the rest needs to be coded)

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  • Register all GUI components as Observers or pass current object to next object as a constructor argu

    - by Jack
    First, I'd like to say that I think this is a common issue and there may be a simple or common solution that I am unaware of. Many have probably encountered a similar problem. Thanks for reading. I am creating a GUI where each component needs to communicate (or at least be updated) by multiple other components. Currently, I'm using a Singleton class to accomplish this goal. Each GUI component gets the instance of the singleton and registers itself. When updates need to be made, the singleton can call public methods in the registered class. I think this is similar to an Observer pattern, but the singleton has more control. Currently, the program is set up something like this: class c1 { CommClass cc; c1() { cc = CommClass.getCommClass(); cc.registerC1( this ); C2 c2 = new c2(); } } class c2 { CommClass cc; c2() { cc = CommClass.getCommClass(); cc.registerC2( this ); C3 c3 = new c3(); } } class c3 { CommClass cc; c3() { cc = CommClass.getCommClass(); cc.registerC3( this ); C4 c4 = new c4(); } } etc. Unfortunately, the singleton class keeps growing larger as more communication is required between the components. I was wondering if it's a good idea to instead of using this singleton, pass the higher order GUI components as arguments in the constructors of each GUI component: class c1 { c1() { C2 c2 = new c2( this ); } } class c2 { C1 c1; c2( C1 c1 ) { this.c1 = c1 C3 c3 = new c3( c1, this ); } } class c3 { C1 c1; C2 c2; c3( C1 c1, C2 c2 ) { this.c1 = c1; this.c2 = c2; C4 c4 = new c4( c1, c2, this ); } } etc. The second version relies less on the CommClass, but it's still very messy as the private member variables increase in number and the constructors grow in length. Each class contains GUI components that need to communicate through CommClass, but I can't think of a good way to do it. If this seems strange or horribly inefficient, please describe some method of communication between classes that will continue to work as the project grows. Also, if this doesn't make any sense to anyone, I'll try to give actual code snippets in the future and think of a better way to ask the question. Thanks.

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  • Which web application framework?

    - by Fergal
    From the following list of frameworks, which one would you use to develop a rich web application and why would you choose it over the others? Sproutcore GWT ExtJS GXT SmartGWT Dojo / Dijit Flex Capuccino Grails

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  • SAXException: Unexpected end of file after null

    - by itsadok
    I'm getting the error in the title occasionally from a process the parses lots of XML files. The files themselves seem OK, and running the process again on the same files that generated the error works just fine. The exception occurs on a call to XMLReader.parse(InputStream is) Could this be a bug in the parser (I use piccolo)? Or is it something about how I open the file stream? No multithreading is involved. Piccolo seemed like a good idea at the time, but I don't really have a good excuse for using it. I will to try to switch to the default SAX parser and see if that helps. Update: It didn't help, and I found that Piccolo is considerably faster for some of the workloads, so I went back.

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  • How to recursively serialize an object using reflection ?

    - by Tony
    I want to navigate to the N-th level of an object, and serialize it's properties in String format. For Example: class Animal { public String name; public int weight; public Animal friend; public Set<Animal> children = new HashSet<Animal>() ; } should be serialized like this: {name:"Monkey", weight:200, friend:{name:"Monkey Friend",weight:300 ,children:{...if has children}}, children:{name:"MonkeyChild1",weight:100,children:{... recursively nested}} } And you may probably notice that it is similar to serializing an object to json. I know there're many libs can do this, can you give me some instructive ideas on how to write this?

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  • What can I access in Androids Native libraries? And How?

    - by Donal Rafferty
    I am completely new to the NDK. I have done a couple of the tutorials including the hello from jni one and another one that calculates the sum of two numbers. They involved using cygwin and the ndk to create the library so file and I have a bit of a grasp on how to insert my own libraries into the libraries layer of Android. I have now been asked to access the native libraries on Android and see what I can use them for. My question is can I do this? The STABLE-APIS.txt document is a bit vague and mentions the following as Stable C++ API's in Android 1.5 cstddef new utility stl_pair.h Does that mean I can access them? If so then how do I go about it? I dont think that following the tutorials I have already done would be any help? Any pointers on how to do this or links to tutorials etc.. would be greatly appreciated

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