# Introduction to Cryptography

By: HakTuts

June 17, 2015

#### What is cryptography?

Cryptography derives its name from the Greek word “Kryptos,” which means “Hidden Secrets.” Cryptography is the practice and study of hiding information. It's the Art or Science of converting a plain intelligible data into unintelligible data and again re-transforming that message into its original form. It provides: Confidentiality, Integrity, Accuracy.

#### Encryption

The process of converting plain text into an unintelligible format (cipher text) is called Encryption.

#### Decryption

The process of converting cipher text into a plain text is called Decryption.

#### What's Key?

In cryptography, a key is a variable value that is applied using an algorithm to a string or block of unencrypted text to produce encrypted text, or to decrypt encrypted text. The length of the key is a factor in considering how difficult it will be to decrypt the text in a given message.

#### What is a Block Cipher?

A method of encrypting / decrypting dataKey is used for encryption / decryption.Same size of I/P and O/P

#### What is Initialization Vector?

An initialization vector (IV) is an arbitrary number that can be used along with a secret key for data encryption.It is a group of hex values.

#### Types of Cryptography

1. Symmetric Key Cryptography (Secret Key Cryptography)2. Asymmetric Key Cryptography (Public Key Cryptography)3. HASH FUNCTION 1. Symmetric Key Cryptography (Secret Key Cryptography)a). Same Key is used by both partiesb). Simpler and Faster2. Asymmetric Key Cryptography (Public Key Cryptography)a). Two  different keys are used  Users get the Key from an Certificate Authority.b). Authentication in asymmetric cryptography is more secured but the process is relatively more complex as the certificate has to be obtained from certification authority.3. HASH FUNCTIONa). Uses mathematical transformation to irreversibly  encrypt information.b). It is a one-way encryptionc). Uses no key for encryption and decryption Image credit: @infosectdk