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Salutare baieti, Am realizat acum ceva timp o aplicatie pentru facultate ce avea ca scop ascunderea textelor in imagini (steganografie). M-am gandit sa o periez putin si sa imbunatatesc algoritmul de ascundere astfel incat sa fie cat mai sigur pentru a o putea impartasi cu voi. Uitati ce am obtinut: [#] Teorie Despre steganografie puteti citi putin aici. Steganografia presupune ascunderea informatiei de interes intr-un mediu neobisnuit astfel incat nimeni sa nu suspecteze prezenta informatiei acolo. Pentru a ascunde textul in imagine, m-am folosit de metoda modificarii bitilor cel mai putin semnificativi (LSB) + un algoritm de criptare a mesajului pe baza unei parole. Desi steganografia nu presupune neaparat criptarea informatiei ascunse, este un pas necesar si linistitor pentru cazul in care apar curiosi. [#] Detalii tehnice: - proiect realizat in Visual Studio 2012 - C# - WPF - framework 4.0; - necesita Windows XP sau mai sus cu .NET framework 4.0 instalat; - nu necesita drepturi de administrator, nu necesita instalare; [#] Mod de utilizare: 1. Pentru ascunderea textului in imagine: - selectati imaginea gazda; - introduceti o parola (optional, dar recomandat); - selectati nuantele de culori ce vor fi afectate de modificari (red - green - blue); - selectati gradul de deteriorare al imaginii (1-2-3 biti); - introduceti textul pe care doriti sa il ascundeti; - apasati lacatelul rosu si salvati noua imagine unde doriti. 2. Pentru recuperarea textului - selectati imaginea ce contine textul ascuns; - introduceti parola (daca ati folosit vreo parola); - apasati lacatelul verde. [#] Cazuri tipice de utilizare - Sunteti la birou si doriti sa va salvati vreo lista de mailuri? Sau poate credentiale foarte importante de logare de la vreo cateva servere? Cautati pe net o poza cu o pisica nebuna, ascundeti informatiile in poza si trimiteti poza intregului departament + mailului personal. Toata lumea va rade, nimeni nu va suspecta o scurgere de informatii. - Ati muncit toata noaptea ca sa obtineti un SQLi in fbi.com? Salvati-va sintaxa intr-o poza cu voi la mare si mergeti la somn. Daca va ia politia peste noapte, nu vor gasi si sintaxa salvata intr-un fisier text. - Vreti sa aveti un jurnal personal, dar nu vreti ca altcineva sa va poata citi gandurile? Scrieti orice trece prin cap si salvati totul in colectia personala de poze porno. Serios vorbind, aplicatia este ideala pentru a ascunde informatii sensibile de ochii curiosilor. [#] Performante - Pentru texte scurte, codarea si decodarea textului in imagine se face instant; - Pentru texte mari, va trebui sa asteptati putin. Pe un quad core cu suficient ram dureaza cam 2 minute pentru a coda sau decoda 25.000 de caractere. - Daca va intrebati cat text are loc intr-o imagine, raspunsul este: destul. Intr-o poza 600x600 am reusit sa introduc vreo 40.000 de caractere. - Puteti sa salvati pozele ca BMP sau PNG; nu vor avea dimensiune mai mare decat alte imagini in formatul respectiv, iar diferentele intre culorile afectate nu sunt sesizabile cu ochiul liber. In final, as vrea sa mentionez ca am acordul lui Nytro pentru a pune acest topic la RST Power. Puteti (si chiar va rog) sa umpleti acest topic cu discutii despre criptografie / steganografie / aplicatie. [#] Download: Multumesc pentru atentie. Stay safe! ~~~~~~~~~~~~~~~ Castigatori treasure hunt: 1. black_death_c4t 2. curiosul 3. Matt Felicitari celor 3! Celor care rezolva in continuare, le pot oferi sursa proiectului.

This tutorial will demonstrate the basics of using LINQ to SQL in C#. What is LINQ Suppose you are writing an application using .NET. Chances are high that at some point you’ll need to persist objects to a database, query the database, and load the results back into objects. The problem is that in most cases, at least with relational databases, there is a gap between your programming language and the database. Good attempts have been made to provide object-oriented databases, which would be closer to object-oriented platforms and imperative programming languages such as C# and VB.NET. However, after all these years, relational databases are still pervasive, and you still have to struggle with data access and persistence in all of your programs. The original motivation behind LINQ was to address the conceptual and technical difficulties encountered when using databases with .NET programming languages. With LINQ, Microsoft’s intention was to provide a solution for the problem of object-relational mapping, as well as to simplify the interaction between objects and data sources. LINQ eventually evolved into a general-purpose language-integrated querying toolset. This toolset can be used to access data coming from in-memory objects (LINQ to Objects), databases (LINQ to SQL), XML documents (LINQ to XML), a file-system, or any other source. So now that we know what LINK is, lets see it in action. We will be implementing a very basic Phonebook. Step 1 - Defining the database You can use agenda.sql file to create the database automatically. Create the two tables in you're SQL server. Persons CREATE TABLE [dbo].[Persons]( [PersonID] [int] NOT NULL, [Name] [nvarchar](30), [Address] [nvarchar](100) Phones CREATE TABLE [dbo].[Phones]( [PhoneID] [int] NOT NULL, [PersonID] [int] NOT NULL, [Number] [char](15), [Description] [nvarchar](50) Step 2 - LINQ to SQL Now we need to link the two tables from the database to our LINQ map(DBML). Open Agenda_Linq.dbml file, delete any tables there and using the Server Explorer from VS drag and drop the two tables from the database in the DBML designer. Now we need to create an association between the two tables: right click-->add-->association. Select Parent class - Persons and Child class and link the files PersonID in the two tables. Now the linking to your database is done. Step 3 - Use LINQ to work with the database Select all persons from Persons table /// <summary> /// Gets all persons. /// </summary> /// <returns></returns> public IEnumerable<Person> GetAllPersons() { Agenda_LinqDataContext agenda = new Agenda_LinqDataContext(); DataLoadOptions option = new DataLoadOptions(); option.LoadWith<Person>(person => person.Phones); agenda.LoadOptions = option; var query = from person in agenda.Persons orderby person.Name select person; var listOfPersons = query.ToList(); agenda.Dispose(); return listOfPersons; } Add/Delete Person internal void AddNewPerson(Person p) { Agenda_LinqDataContext agenda = new Agenda_LinqDataContext(); agenda.Persons.InsertOnSubmit(p); agenda.SubmitChanges(); agenda.Dispose(); } internal void DeletePerson(Person selectedPerson) { Agenda_LinqDataContext agenda = new Agenda_LinqDataContext(); agenda.Persons.Attach(selectedPerson); agenda.Persons.DeleteOnSubmit(selectedPerson); agenda.SubmitChanges(); agenda.Dispose(); } Add/Delete Phone internal void AddPhone(Phone p) { Agenda_LinqDataContext agenda = new Agenda_LinqDataContext(); agenda.Phones.InsertOnSubmit(p); agenda.SubmitChanges(); agenda.Dispose(); } internal void DeletePhone(Phone phone) { Agenda_LinqDataContext agenda = new Agenda_LinqDataContext(); agenda.Phones.Attach(phone); agenda.Phones.DeleteOnSubmit(phone); agenda.SubmitChanges(); agenda.Dispose(); } You get the picture. As you can see the database is transformed in C# classes by the DBML and you are using now those classes instead of the actual database. Full source code here: hg clone https://bitbucket.org/rokill3r/linqagenda Alien