Introduction to Cryptography

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.

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

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 data. Key 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)


1. Symmetric Key Cryptography (Secret Key Cryptography)

a). The Same Key is used by both parties

b). Simpler and Faster

2. Asymmetric Key Cryptography (Public Key Cryptography)

a). Two different keys are used  Users get the Key from a 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 the certification authority.


a). Uses mathematical transformation to irreversibly encrypt information.

b). It is a one-way encryption

c). Uses no key for encryption and decryption.