SHA256 using OpenSSL library (Linux)

I love cryptography and it was one of my favorite subjects in college. So recently when at work, I was asked to compute SHA256 for some data, I did some reading and learnt a lot of new stuff. I love learning anything new so enjoyed this exercise a lot. One of those days when work can be actually fun!

“A cryptographic hash (sometimes called ‘digest’) is a kind of ‘signature’ for a text or a data file. SHA-256 generates an almost-unique 256-bit (32-byte) signature for a text. A hash is not ‘encryption’ – it cannot be decrypted back to the original text (it is a ‘one-way’ cryptographic function, and is a fixed size for any size of source text). This makes it suitable when it is appropriate to compare ‘hashed’ versions of texts, as opposed to decrypting the text to obtain the original version. Such applications include stored passwords, challenge handshake authentication, and digital signatures.” (taken from here).

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Using Crontab

Crontab command is used to edit crontab files. These files have a list of commands that are to be executed on a particular day at a given time. They are most useful when you want to run some tests or some cleanup commands or something that needs to be run regularly – say weekly or monthly. The commands specified are executed automatically and logs can also be collected from those commands, along with an email that will be sent to the user. I had not used this feature until recently when I was asked to use them at my job. These crontab files are maintained per user, so each user can configure his own commands to be run.

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Ubuntu on my Macbook

I own a Macbook Pro for sometime now and had installed windows on it along with Mac OS. Windows kept crashing every few days and I had to reinstall it repeatedly. Finally, I got fed up and removed it completely from my Macbook. I have always loved Ubuntu as it is extremely user friendly and is powerful, owing to the fact that it has Linux Kernel. Having used Ubuntu while I was in University, I have a special kind of liking towards it. That was when I decided that I want to install Ubuntu on my Macbook.

How did I install Ubuntu?


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Mac or a PC?


Who : Avada Kedavra
What : Mac or a PC?
Spicy : Not everyday do you get a technical post from Avada Kedavra. In this post you get to know the technical gyaan on whether to go for a Mac or a PC. Read it now.


The age old battle of which operating system is better for a computer is still ON! Just yesterday we had a battle at my workplace where in some of my teammates were Windows supporters and some Linux and Mac. We spent almost one and a half hours arguing which one was better. Each has its own advantages and disadvantages and neither of them is the best OS in market for sure.

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Leaps in technology

Back to my same old theme.. 😀  I was thinking about how the technology is getting advanced day by day.. I mean, there was a time when people did not have a computing machine or even a calculator.. Everything was done manually.. Today, we even have PDAs and Iphones.. I recently watched an episode about Chimpanzees.. They are our closest ancestors.. Even though they are intellectually almost as good as a human, we are studying about them and it is not vice versa..

I remember those days when the computer came to India.. We were so small and in school and we had a computer science subject.. We just had one huge computer in the entire school and the teacher would take us to the room, which had so much of air conditioning that any person would catch cold.. You have to remove your slippers before entering the room (as if it was a god and you are entering a temple 😛 ) We got so much fascinated after seeing it and reading about CPU or ALU etc and they just had DOS as the operating system initially.. Then after some years, they invented Windows 3.1 operating system which had all the fancy stuff like Program manager and all the nonsense… Yes! I had learnt Windows 3.1 then.. It introduced all the new concepts like that of an icon and I guess, a device called “Mouse” came into existence after that.. But still the machines were so huge and were so bulky too..


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Wireless card setup in Linux

I am a newbie in Linux…havent used it much other than for the curriculum projects… I had to set up wireless network on my laptop since I wanted to access Internet from Linux… I had found an alternative for this by using the Ethernet cable from the modem.. But it was very inconvenient since I had to sit in the vicinity of that cable in order to have internet access while working in Linux.. I googled a lot and read through lot of articles in the linux forums and finally did the following in order to set it up:

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