From: Enar Väikene Date: Thu, 21 Jul 2011 14:08:55 +0000 (+0300) Subject: Work started on the tutorial. X-Git-Url: https://vaikene.ee/gitweb/overview.html?a=commitdiff_plain;h=1d2a1e80abac012e9755cd23b264e3e099ccc3f5;p=evaf Work started on the tutorial. --- diff --git a/www/evaf.css b/www/evaf.css index 88bf274..ad5f778 100644 --- a/www/evaf.css +++ b/www/evaf.css @@ -27,6 +27,9 @@ h2 { font-size: 150%; margin-left: 20px; } +h3, h4 { + margin-left: 20px; +} p { margin-left: 1.5em; margin-right: 0.5em; diff --git a/www/index.html b/www/index.html index d407dff..bb4b222 100644 --- a/www/index.html +++ b/www/index.html @@ -21,6 +21,7 @@

diff --git a/www/pswgen01.html b/www/pswgen01.html new file mode 100644 index 0000000..4bc5917 --- /dev/null +++ b/www/pswgen01.html @@ -0,0 +1,98 @@ + + + + + + eVaf Tutorial - 01 - Introduction + + + + + + + + +

eVaf Tutorial

+ +

01 - Introduction

+ +

On this page we write an application using the eVaf application development framework. Knowledge of the + C++ programming language and Qt application and UI framework are required. The tutorial is written + for Linux, but with small modifications the same application can be written on Windows.

+ +

Specification

+ +

We try to be good programmers and start with a short specification for the application before writing any code.

+ +

In 2011 the PlayStation Network was hacked and sensitive data including user names and passwords stolen. I as many other normal + people used the same password on PSN as well as on many other online services. Once one of them was compromised, all the passwords needed + to be changed.

+ +

We are most secure when we use unique passwords for each and every web site and online service. So let us write an application that can + be used to generate unique passwords. We do it in such a way that whenever we need to re-enter a password, we can re-create it without + actually storing the password on our hard disks.

+ +

For this we are going to write a password generator using cryptographic hash functions. By feeding the password generator with the + same input data, we end up with the same password. All we need to remember is the input data we entered when generating the password.

+ +

For the input data, we can combine a name of the online service with a master password that only we know. We do not store the master + password, do not send it to any of the web pages nor can it be figured out from the generated password. Only things that we may want to + store are optional parameters for the password generator, like the length of the password.

+ +

The application is simple and, for example, Firefox already has many add-ons that do exactly what we are going to write. To make it an + eVaf application, we are going to split it into modules and define interfaces to work with them. Every module does it's on job and can + be easily replaced if we wanted so:

+ +

Generator -- Module that generates passwords using a cryptographic hash function. We are going to use simple MD5 hash function + in this tutorial, but it can be replaced with better methods that are more collision resistant than MD5.
Storage -- Module that stores optional parameters for the password generator. As these parameters are actually not sensitive + information, we do not use any encryption here, but the module can be replaced with another one that uses encryption.
User Interface -- Module that implements the GUI for the application.

+ +

Generator Module

+ +

The Generator module really needs to do only one job -- generate passwords in such a way that by feeding it with the same input data, + the same password gets generated. Input data for the password generator is:

+ +

Name -- Name of the application, online service or web page for which the password is generated. This could be, for example, + "facebook.com" or "google.com".
Master Password -- Password that only we know and is used for all the generated passwords.
Length -- Length of the generated password. We prefer passwords that are as long as possible, but some applications or web sites + may require passwords that are shorter.
Options -- Additional parameters for the password generator. We are not going to use these in this tutorial, but they could be + used to force the password generator to use a limited set of characters, like alpha-numeric only etc.

+ +

We also may want to know the maximum length of the generated password. The maximum length depends on + the cryptographic hash function used in the module and we need a function in the interface for this.

+ +

Storage Module

+ +

The Storage module stores non-sensitive data required to re-generate passwords:

+ +

Name -- The same name of the application, online service or web page that was used in the Generator module.
Length -- Length of the password.
Options -- Additional parameters for the password generator if they were used.

+ +

We need a function in the interface that can be used to store input data for the generator when a password is generated.

+ +

We also need functions to query stored data identified by the Name value. The query function could work with partial matches so that + when we enter "fa" into the user interface, it offers "facebook.com" if this record is found.

+ +

User Interface Module

+ +

The User Interface module provides us with a window where we can enter necessary input data and generate passwords. Once the password is + generated, we want it to store non-sensitive input data and optionally copy the generated password to the clipboard.

+ +

If the Storage module supports this, then the User Interface module could also offer existing names based on the initial input.

+ +

In the next section 02 - Preparations we prepare the development environment.

+ + + +