Introduction of Cryptography Computer Science YouTube Lecture Handouts

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Introduction of Cryptography

1. Introduction of Cryptography

2. What is Cryptography?

3. Processes of cryptography

4. How it works

5. Types of Cryptography

6. Symmetric Key Cryptography

7. Asymmetric Key Cryptography

8. Public key

9. Private Key

10. MCQs

Introduction of Cryptography

Introduction of Cryptography

Cryptography is a an art by which we can protect our data and information. The word Cryptography is derived from the Greek word called “Kryptos” which means “Hidden Secrets” .

What is Cryptography?

This is a technique by which we convert plain text to cipher text and cipher text are again converted to plain text.

A Plain text means a message that anyone can read and understand its meaning. But ciphers text is a message that can be read but cannot be understood that what it is written and what it means. This data can be read only by the one who has the secret key to decrypt it. It is used to protect email message credit card details and other important information. It provides Confidentiality, Integrity, and Accuracy.

Processes of Cryptography

Cryptography has two important processes, encryption and decryption.

In Encryption plaintext is converted to cipher text.

Decryption again converts the cipher text to plain text.

How It Work

It converts the service message into code, scrambles it and creates the encryption key. After this only one can unlock this message for which the message is.

Types of Cryptography

There are two types of Cryptography

  • Symmetric Key Cryptography
  • Asymmetric Key Cryptography
Types of Cryptography

Symmetric Key Cryptography

Only one key is used meaning that it has the same key for encryption and decryption. In this, data or information is encrypted and decrypted using a same key.


It is simple and fast


Less secured.


Asymmetric Key Cryptography

It has different keys for both encryption and decryption. In this Public key and private key are two types of keys and both key are interrelated.

  • Public key is used to encryption.
  • Private Key is used to decryption.


It is more secure & Authentication


Very complex


Public Key

  • Public key is used for encryption, hence it is also called encryption key.
  • The public key belongs to the receiver but receiver shares it with the sender, through which the sender encrypt its message and send it to the receiver via the channel.

Private Key

  • Private is the key that the receiver does not share with anyone.
  • When the sender encrypts the message with the public key, the receiver can read it by decrypting it via the private key. This keeps the security.

Advantages of Cryptography

Cryptography has many advantages because encryption makes data completely safe and secure. After encrypting the data, even if it is hacked or stolen, no one can access or read the data.


With the use of Cryptography technology, the data can be kept safe and secure, by it use it remains and appropriate unit of privacy, authentication, integrity, access control and data availability.


Q1. What do you mean by cipher text?


1. Ordinary text

2. Encrypted text

3. Readable text

4. Decrypted

Answer: 2

Q2. What is the use of the public key for?

1. Encryption.

2. Description.

3. Encryption and description both

4. None of these

Answer: 1

Q3. How many keys use in Asymmetric Key Cryptography?

1. Only one key

2. Two different key

3. Four key

4. None of these

Answer: 2

Topics discussed:

#Introduction of Cryptography

#What is Cryptography

#Processes of cryptography

#How it work

#Types of Cryptography

#Symmetric Key Cryptography

#Asymmetric Key Cryptography

#Public key

#Private key