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Archive for the ‘Experiments’ Category

Anagram Solver in C

September 18, 2011 Leave a comment

Hi, Here’s a small anagram solver written in C. It works based on generating permutations of given string and comparing them using a dictionary. For fast search in dictionary, the program first creates an index of the starting location of each alphabet. It takes a few minutes to process long words.

Here’s the source code. Suggestions are always welcome, Greetings 🙂

Update: There’s a little problem in using the term ‘anagram solver’ here. An anagram solver finds words from another valid word – But this program finds words from the characters of given valid/invalid word.  Thanks to technikhil for the info 🙂

A cryptographic tool that converts weak password into a strong password before encrypting

Here’s a small encryption/decryption tool that works based on AES algorithm. No matter how weak your password is, the program converts it to a  32 digits hexadecimal number  before encrypting. This is achieved by finding the MD5 hash of the password using hashlib python module. This hash is used to encrypt the file.

The source file is here

The idea in my mind while writing this program was this:

Suppose a cracker gets an encrypted file and he figures out it’s encrypted using AES somehow. Then he starts brute force attack on it to find the key and extract information. If the password used to encrypt that file is weak and if it’s based on a dictionary word, the cracker can easily figure out the password. Hence the password  given by the user must be made stronger by the encrypting program. And the best way to make a password strong is by using  digest algorithms since it’s unique to a string.

What do you think? Am I wrong? Thank you 🙂

 

A small and simple note taking app

Wrote a small python script that can be used with your favorite text editor as a simple note taking application. Hope you like it, suggestions are always welcome 🙂

Here’s the code!

Thank you 🙂

C program to extract email IDs from a file

Here’s a small program to extract email IDs from an input file. It could have done using regex (in Python or  in any other high level language), but doing it in C is more fun, eh? 🙂

The code is here!

Usage: parseEmail [FILE]

Suggestions and improvements are always welcome 🙂 Thank you!

Setting up a Debian repo in LAN

It was really a nice experience going to MES College Of Engineering, Kuttippuram last week to attend Debian Mini Conf 2011. Met friends, made new friendships and learned many new things from there. Thanks to Jishnu ettan, for giving me a 50GB Debian repo that contains all the packages of squeeze of both i686 and amd64 architectures. Today, I will explain how to set up a Debian repo (squeeze) so that it be can shared over LAN.

First, run terminal and switch to root user.

$su

If you have the repo as an ISO image file, we need to mount it to a directory. The following command does that:

#mount <path-to-iso> <path-to-mount> -o loop

Edit /etc/apt/source.lst and add the repo we mounted. Append the following line to the file:

deb file:///<mounted-path> squeeze main

Update the package list:

#apt-get update

We are going to share the files using http, hence we need a webserver. To install apache:

#apt-get install apache2

Make a symbolic link of <mounted-path> in /var/www

#ln -s /var/www/repo <mounted-path>

Done! Now add this machine as a repository in other Debian systems in LAN, edit /etc/apt/source.lst to:

deb http://<ip-of-server>/repo squeeze main

The same can be done using a FTP server. All you have to do is to make the symbolic link in FTP’s configured path and use ftp:// instead of http:// in /etc/apt/source.lst. Thank you 🙂

A sudoku checking program in C :)

It just started when my younger bro, Shafeeq who reads hacker news everyday, found a little interesting blog post. It was about the authors experience in applying for an internship at Google. The candidate was asked to write a program to check a completed sudoku during the telephone interview  for errors, in his favorite programming language. I asked bro, “Why don’t you give it a try?!”. He’s now in 11th standard and started coding in C++ which he learns in Computer Science subject.  He came up with the code in one day, and then it was my turn to do that 🙂 Here’s the way I solved the problem and it’s in pure C.

You can find the code here, in github. The input is given as a plain text file that contains 9×9 numbers separated by space. A sample input is given below:

7 2 3 8 4 6 1 5 9
6 1 5 3 9 2 4 7 8
8 4 9 7 1 5 6 3 2
3 7 8 6 5 4 9 2 1
1 9 4 2 8 7 3 6 5
2 5 6 9 3 1 8 4 7
5 6 1 4 7 9 2 8 3
4 8 7 1 2 3 5 9 6
9 3 2 5 6 8 7 1 4

And to check for errors, please call the program with the file as argument, like this –

$checksudoku <data_file>

Hope you enjoyed it, Please go through the code and feel free to post your valuable comments and suggestions here. Thank you 🙂

The little twitter client I use :)

Here’s a small python script to update and read tweets from different timelines. You can use it with head/tail commands to customize the output. Actually, I wrote this script just for personal use and now I would like to share it with you 🙂 Thanks to tweepy python module, make sure it’s installed before trying the script 🙂

#!/usr/bin/env python
# Copyright 2011 Ershad K <ershad92@[nospam]gmail.com>
# Licensed under GPL Version 3

import sys
import tweepy

CONSUMER_KEY = ' Fill here'
CONSUMER_SECRET = ' File here too'
ACCESS_KEY = ' Type yours here'
ACCESS_SECRET = 'Type yours here too'

auth = tweepy.OAuthHandler(CONSUMER_KEY, CONSUMER_SECRET)
auth.set_access_token(ACCESS_KEY, ACCESS_SECRET)
api = tweepy.API(auth)

if sys.argv[1] == 'u':
    api.update_status(sys.argv[2])

elif sys.argv[1] == 'p':
    public_tweets = api.public_timeline()
    for tweet in public_tweets:
        print tweet.user.screen_name,":",tweet.text
        print ""

elif sys.argv[1] == 'r':
    mention_tweets = api.mentions()
    for mtweet in mention_tweets:
        print mtweet.user.screen_name,":",mtweet.text
        print ""

elif sys.argv[1] == 'h':
    friends_tweets = api.home_timeline()
    for ftweet in friends_tweets:
        print ftweet.user.screen_name,":", ftweet.text
        print ""

Hope you like it 🙂