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Cryptography

Cryptography is a technique to secure data and communication. It is a method of protecting information and communications through the use of codes, so that only those for whom the information is intended can read and process it. Cryptography is used to protect data in transit, at rest, and in use. The prefix crypt means "hidden" or "secret", and the suffix graphy means "writing".

In Cryptography the techniques which are use to protect information are obtained from mathematical concepts and a set of rule based calculations known as algorithms to convert messages in ways that make it hard to decode it. These algorithms are used for cryptographic key generation, digital signing, verification to protect data privacy, web browsing on internet and to protect confidential transactions such as credit card and debit card transactions.

Techniques used For Cryptography

In today’s age of computers cryptography is often associated with the process where an ordinary plain text is converted to cipher text which is the text made such that intended receiver of the text can only decode it and hence this process is known as encryption. The process of conversion of cipher text to plain text this is known as decryption.

Encryption

Encryption is the process of converting plain text to cipher text. The process of encryption is done by using a key which is a secret code. The key is used to encrypt the plain text and the cipher text is obtained. The key is used to decrypt the cipher text and the plain text is obtained. The key is kept secret and is known only to the sender and the receiver of the message.

Decryption

Decryption is the process of converting cipher text to plain text. The process of decryption is done by using a key which is a secret code. The key is used to decrypt the cipher text and the plain text is obtained. The key is used to encrypt the plain text and the cipher text is obtained. The key is kept secret and is known only to the sender and the receiver of the message.

Types of Cryptography

There are two types of cryptography:

  1. Symmetric Cryptography
  2. Asymmetric Cryptography

Symmetric Cryptography

In symmetric cryptography the same key is used for encryption and decryption. The key is kept secret and is known only to the sender and the receiver of the message. The key is used to encrypt the plain text and the cipher text is obtained. The key is used to decrypt the cipher text and the plain text is obtained. The key is kept secret and is known only to the sender and the receiver of the message.

Asymmetric Cryptography

In asymmetric cryptography two different keys are used for encryption and decryption. One key is used for encryption and the other key is used for decryption. The key used for encryption is known as public key and the key used for decryption is known as private key. The public key is made public and is known to everyone. The private key is kept secret and is known only to the sender and the receiver of the message. The public key is used to encrypt the plain text and the cipher text is obtained. The private key is used to decrypt the cipher text and the plain text is obtained. The key is kept secret and is known only to the sender and the receiver of the message.

Hash Functions

Hash functions are used to map data of arbitrary size to data of fixed size. The values returned by a hash function are called hash values, hash codes, digests, or simply hashes. The values are used to index a fixed-size table called a hash table. Use of a hash function to index a hash table is called hashing or scatter storage addressing.

Popular Cryptography Algorithms

  1. Caesar Cipher
  2. Vigenere Cipher
  3. Playfair Cipher
  4. DES
  5. AES
  6. RSA
  7. Diffie-Hellman Key Exchange
  8. ElGamal
  9. Digital Signature Algorithm
  10. Elliptic Curve Cryptography

NOTE:

1. *RSA* means Rivest–Shamir–Adleman. 
2. *DES* means Data Encryption Standard. 
3. *AES* means Advanced Encryption Standard.

Features Of Cryptography are as follows:

Confidentiality:

Information can only be accessed by the person for whom it is intended and no other person except him can access it.

Integrity:

Information cannot be modified in storage or transition between sender and intended receiver without any addition to information being detected.

Non-repudiation:

The creator/sender of information cannot deny his intention to send information at later stage.

Authentication:

The identities of sender and receiver are confirmed. As well as destination/origin of information is confirmed.

Crypto Currency

Crypto currency is a digital currency in which encryption techniques are used to regulate the generation of units of currency and verify the transfer of funds, operating independently of a central bank. Cryptocurrencies use decentralized control as opposed to centralized digital currency and central banking systems. The decentralized control of each cryptocurrency works through distributed ledger technology, typically a blockchain, that serves as a public financial transaction database. A defining feature of a cryptocurrency, and arguably its most endearing allure, is its organic nature; it is not issued by any central authority, rendering it theoretically immune to government interference or manipulation.

Features of Crypto Currency are as follows:

  1. Decentralized
  2. Anonymous
  3. Secure
  4. Transparent
  5. Immutable
  6. Fast

Types of Crypto Currency are as follows:

  1. Proof of Work
  2. Proof of Stake

Proof of Work

Proof of work (PoW) describes a system that requires a not-insignificant but feasible amount of effort in order to deter frivolous or malicious uses of computing power, such as sending spam emails or launching denial of service attacks. The concept was subsequently adapted to securing digital money by Hal Finney in 2004 through the idea of "reusable proof of work" using the SHA-256 hashing algorithm.

Most Popular Proof of Work Crypto Currency are as follows:

  1. Bitcoin
  2. Litecoin
  3. Dogecoin

Proof of Stake

Proof-of-stake is a cryptocurrency consensus mechanism for processing transactions and creating new blocks in a blockchain. A consensus mechanism is a method for validating entries into a distributed database and keeping the database secure. In the case of cryptocurrency, the database is called a blockchain—so the consensus mechanism secures the blockchain.

Most Popular Proof of Stake Crypto Currency are as follows:

  1. Ethereum
  2. EOS
  3. Cardano

Blockchain

Blockchain is a distributed database that maintains a continuously growing list of ordered records called blocks. Each block contains a cryptographic hash of the previous block, a timestamp, and transaction data. By design, a blockchain is resistant to modification of the data. It is "an open, distributed ledger that can record transactions between two parties efficiently and in a verifiable and permanent way".

Features of Blockchain are as follows:

  1. Decentralized
  2. Immutable
  3. Transparent
  4. Secure

Types of Blockchain are as follows:

  1. Public Blockchain
  2. Private Blockchain

Public Blockchain

A public blockchain is a blockchain that is accessible to anyone. Public blockchains are open to anyone who wants to participate in the network. This means that anyone can view the blockchain and its transactions, and anyone can participate in the network by mining and validating transactions. Public blockchains are also known as permissionless blockchains.

Private Blockchain

A private blockchain is a blockchain that is only accessible to a select group of people. Private blockchains are not open to the public. This means that only a select group of people can view the blockchain and its transactions, and only a select group of people can participate in the network by mining and validating transactions. Private blockchains are also known as permissioned blockchains.