What is Encryption and Decryption? - The Hackash

Learn about Cryptography Basics Encryption and decryption

 In this post, we will talk about some of the basics of cryptography like what is cryptography and why do we need it etc. After that we will discuss the traditional cryptography model which is based on encryption and decryption of messages.

 So let's start. When we are talking about communication over a network we need to make sure that there is some sort of security for the information being communicated. Now a question might pop up in your mind  as to why do we need this security during transmission?

Let me explain this with an example. Suppose you are shopping online with your laptop and you use your credit card for payments.  At this time your credit card information is sent to the server for verification.  Now the server at the end of this line might provide security for your information

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  when the information is within the server. But what about the time when it is under transmission?  If there is no security here, the information is vulnerable.  A hacker might easily tap out your credit card information and empty your pockets! You wouldn't want that, do you?  So the information needs to be protected when it is travelling through the network.

 If you just think about the things you do over the internet it is easy to point out many such examples where you need security. Whether it is sending personal emails or any web transactions or confidential information being transmitted between military organizations everywhere SECURITY is an important requirement!

 So how do we provide this security during transmission then? Well, One way of ensuring security can be use of CRYPTOGRAPHY Cryptography is a field of network security which deals with hiding "real" infromation when it is under transmission between two parties. Usually, the real information is transformed or hidden into another message and transmitted over the network.

 This transformed message in itself will make no sense even if any hacker gets hold of this information.  When it reaches the destination the reciepent will know a method to de-transform the garbage message into its original message which was sent by the Sender I will give you a simple Example.

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Let us say a boy Bob wants to send a message "I love you" to his girlfriend Alice Now he wouldnt want anyone else to see this message Let us say he uses a software to convert the message  into some numbers say "143" and this software is available is only with Alice and Bob and nobody else Now 143 is sent across the network to Alice.

If a hacker gets hold of this message 143 he will not be able to guess what is the real information  because he does not have this conversion software So the real information is safe When the message reaches Alice,  she will use the same software to convert 143 to real message, "I love you" And she will be happy seeing the message,won't she!

 So this method of transforming message at sender's side and de transforming at reciever's side forms the basic model of Cryptography. Converting real information into what looks like garbage value this process is called as Encryption

Encryption meaning to say you are hiding or locking the real information into some other form And the process of extracting real information back from this meaningless text is called as Decryption meaning to say we are unlocking or extracting the original message that was sent Let us now see this cryptography model a little more technically.

So this is the skeletion of the model Let us define it more clearly First, the information to be transmitted is called as plain text(or message) is fed to an Encryption system. The Encyrption system uses a key to convert the plain text to encyrpted form which looks like garbage value This is also called as cipher text.

 A corresponding key is used at the other end to decrypt the cipher text back to original message When we say a "key" it actually means a piece of string value which is fed to encyprtion and decryption algorithms along with the text for transformation This is similar to locking your valuable things in a box and sending it across At the other end the reciever will use the secret key to open the box and read the message you (Sender) sent.

 If a hacker were to tap out the message being transmitted in the network he will get the encrypted message, say "143" Now he will not have the key to decrypt this message so this cipher text will not mean anything to him.

He may try to use several methods to break this code and get the hidden message out of this This art of trying to break ciphers forms a different branch of study called as Cryptanalysis but we will not go into that right now This Encrption and Decryption together ensure security of the message being transmitted across the network.

This whole encryption and decryption strategy is based on the premise that both sender and reciever share some unique keys which is not known by any outsiders, like the hackers.

Depending on how the keys are shared we can classify crytography as Symmetric and Asymmetric If the keys used by both parties are same then it is called symmetric key cryptography or private key cryptography .

If both parties use different keys for encyrption and decryption then it is called asymmetric key cryptography or public key cryptography We will stop it here for this video In our next videos in cryptography series we will discuss private and public key cryptography in detail and also the various methods and algorithms used under these to ensure security of messages.