Thursday, March 28, 2019
What is Cryptography and how does it works?
Cryptography
Cryptography is essentially important because it allows you
to securely protect data that you don't want anyone else to have access to. It
is used to protect corporate secrets secure classified information and to
protect personal information to guard against things like identity theft.
Hi
guys my name is Sagar Panta and I welcome you all to another session on cyber
security and today's post is basically going to be about cryptography. Now
before we actually jump into the session let me give you guys a brief on the
topics that we're going to cover today. So, first of all we're going to cover
what is cryptography to the help of a very simplistic scenario then we are
going to go through the classifications of cryptography and how the different
classification of algorithm works. So, let's get started.
Now I'm going to take
the help of an example or a scenario to actually explain what is cryptography.
All right so let's say we have a person and let's call him Andy I suppose Andy
sends a message to his friend Sam who is on the other side of the world now
obviously. He wants this message to be private and nobody else should have
access to the message now he uses a public forum for example the internet for
sending this message. The goal is to actually secure this communication and of
course we have to be secure against someone. Now, let's say there is a smart
guy called Eve who is secretly got access to your communication channel. Since,
this guy has access to your communication he can do much more than just
eavesdrop. For example, he can try to change the message in itself. Now, this
is just a small example what if Eve actually gets access to your private
information. Well, that could actually result in a big catastrophe. So, how can
Andy be sure that nobody in the middle could access the message sent to Sam??
The
goal here is to make communication secure and that's where cryptography comes
in. So what exactly is cryptography?? Well
cryptography is the practice and the study of techniques for securing
communication and data in the presence of adversaries so let me take a moment
to explain how that actually happens. Well first of all we have a message, this
message is firstly converted into a numeric form and then this numeric form is
applied with a key called an encryption key and this encryption key is used in
an encryption algorithm. So, once the numeric message and the encryption key
has been applied in an encryption algorithm what we get is called a Ciphertext.
Now, this Ciphertext is sent over the network to the other side of the world
where the other person whose message is intended for will actually use a
decryption key and use the ciphertext as a parameter of a decryption algorithm
and then he'll get what we actually sent as a message. If some error had actually occurred he'd get
an error. So, let's see how cryptography can help secure the connection between
Andy and Sam. So, to protect his message Andy first converts his readable
message to an unreadable form. Here he converts a message to some random
numbers and after that he uses a key to encrypt his message. After applying
this key to the numerical form of his message he gets a new value in
cryptography we call this ciphertext. So now, if Andy sends the cipher text or
encrypted message over communication channel he won't have to worry about
somebody in the middle of discovering the private message. Even if somebody
manages to discover the message he won't be able to decrypt the message without
having a proper key to unlock this message. So suppose Eve here discovers the
message and he somehow manages to tamper with the message and message finally
reaches Sam. Sam would need a key to decrypt the message to recover the
original plain text. So, using the key he would convert a ciphertext to
numerical value corresponding to the plain text.
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