Sunday 14 August 2016

Key Based Cryptographic Algorithms

Hello everyone. With my previous blogs, we have come to know a little about
Technique Based Cryptographic Algorithms and their working mechanisms. In this
blog, I will be discussing about Key Based Cryptographic Algorithms. Key based
algorithms are fairly harder than the Technique based algorithms. These involve
more complex concepts that make these algorithms far more secure than Technique
based algorithms.

Before going into the details of Key based algorithms, there is another small
classification of the algorithms that categorize into parts :

1. Stream Cipher -  In this cipher, one by one character is processed at a time.

2. Block Cipher -  In this cipher, a fixed size block is extracted from the whole
   plain text and then one by one character is processed at a time.

We will start to see the significance of this classification once we start digging into
the algorithm demonstrations.

So, let's come back to the classification of Key Based Algorithms. There are two types :

1. Symmetric Key Cryptography or Private Key Cryptography :
   In this type of cryptography, only one key is used and the same key is used to encrypt
   and decrypt the message. Both parties must agree upon the same key before any
   transmission begins. This key should be only known to the two parties and no one else.
   That's why it is also called as Private Key Cryptography or Secret Key Cryptography.
   Example - DES, IDEA, RC4, RC5, BlowFish, AES, etc.



2. Asymmetric Key Cryptography or Public Key Cryptography :
   In this type of cryptography, two different keys are used - one is public key which is
   available to all for encrypting the message and the other one is private key which is
   available only to the receiver for decrypting the message. Both the keys are generated
   by the receiver but only the public key is sent to the sender for encryption. Any sender
   can encrypt the message with the public key but only receiver can decrypt the message
   with the private key. This feature ensures that only the intended person can only read
   the message and no one else. That's why it is also called Public Key Cryptography.
   Example - Merkle's Puzzles, RSA, ElGamal, ECC, etc.



In my next blogs, I will start with the demonstrations of Symmetric Key Cryptographic
Algorithms. That's all for this blog.

I hope you find it useful. Till then keep coding.

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