Everything you need to know about the basics of Cryptography

Well, In this everyday changing technology, we all need secure communication from one medium to another. Cryptography plays an important role in maintaining the integrity of the data transferred to ensure that data is not altered/accessed by unauthorized folks. In this article, I will be briefing about the basics and types of cryptography that we use in our digital transactions.

What is Cryptography?

Cryptography is the method of securing data, information, and communications through the use of encrypted codes so that only those persons for whom the information is meant can understand it and process it. Thus preventing unauthorized access to information. The prefix “crypt” means “hidden” and the suffix “graphy” means “writing”. It not only protects data from theft or modification but can also be utilized for user authentication.

Types of Cryptography:

Symmetric Key Cryptography-

Symmetric Key: An encryption technique in which the sender & receiver of a message share a single, common key that is used to encrypt & decrypt the message. The most popular symmetric key system is the Data Encryption Standard (DES).

Symmetric Key is broken down further into two categories- Classical & Modern Cryptography.

Classical Cryptography consists of two types- Transposition & Substitution Cipher as described below:

Transposition Cipher: It is a method of encryption by which the positions held by units of plaintext (which are commonly characters) rearrange the order of the letters in the ciphertext so that the ciphertext comprises a permutation of the plaintext.

Substitution cipher: It is a method of encrypting by which plaintext is replaced with ciphertext, specifically replacing in the ciphertext all the letters of the first row with the letters associated with the second row.

Modern Cryptography is sub-divided into two types: Stream and Block Cipher

Stream Cipher: It is a symmetric key cipher where the conversion of plain text combined with a pseudorandom cipher digit stream by taking one byte of the plain text at a time. In a stream cipher, each plaintext digit is encrypted one at a time with the related digit of the keystream, to give a digit of the ciphertext stream. It uses 8 bits and decryption of text is easy. Hence, not in use nowadays.

Block Cipher: It is a deterministic algorithm that works on fixed-length groups of bits, called blocks to produce a seemingly-random output of the same size. It uses a symmetric key and complexity is quite simple. Block Cipher uses either 64 bits or more than 64 bits which makes it harder to decrypt the text.

Asymmetric Key: Aka, Public-Key Cryptography is a cryptographic system that requires the use of a public-key and a private key. Public keys can be distributed widely, and private keys are known only to the owner.

Example of Asymmetric Key:

RSA Algorithm: RSA (Rivest–Shamir–Adleman) is an algorithm used by modern computers to encrypt and decrypt messages which is an asymmetric cryptography algorithm; this means that it uses a public key and a private key (i.e two different, mathematically linked keys). This is also called public-key cryptography because one of the keys can be accessed by anyone. An example is shown below:

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