Cryptography L01- Introduction

outline

Historically

What is cryptography

Cryptography goals

Cryptography sections

● Encryption

● Decryption

Cryptography keys and their importance

Types of Cryptography keys

● public Key

● private key

2

Historically

Information security is the practice of defending information from

unauthorized access, use, disclosure, disruption, modification,

perusal, inspection, recording or destruction. It is a general term that

can be used regardless of the form the data may take.

Information security uses cryptography to transform usable information into a form that renders it unusable by anyone other

than an authorized user; this process is called encryption.

3

What is cryptography

Known as encryption codes to convert the information is

understandable process , To prevent unauthorized persons from access to information or misunderstood.

It uses the science of mathematics is you can store sensitive

information transmitted over insecure networks and secure from

hackers and vandals tamper and thieves.

4

Cryptography goals

Confidentiality: keeping information secret from all but those who

are authorized to see it.

Integrity: ensuring information has not been altered by unauthorized

or unknown means.

Availability: keeping information accessible by authorized users

when required

5

Cryptography goals 6

Confidentiality

Availability Integrity

Cryptography sections

Encryption :

It is turning information into incomprehensible symbols using encryption

algorithms process.

It includes encryption texts, images, audio, ...

The picture shows texts encryption process:

7

Cryptography sections

Decryption :

It is the opposite of the encryption process is the conversion of non-

understood codes to understandable using Decryption algorithms

process.

8

Cryptography keys and their

importance

What is the key?

Is a secret number by the length algorithm type, for example(6-bit)it is

used for the encryption and decryption process.

► What is importance ?

No one can decryption data without the encryption key that has been done Encryption.

9

Types of Cryptography keys

Public key :

Is the number that is traded and spread among the rest of the users to

encrypt any information or customized for you e-mails is a public key

based encryption process nor can one decode that information else

you because they need a PIN number Let it is private key to complete

the calculation and access to the key figure basis and thus open the

files again.

10

Types of Cryptography keys

Private key :

The other half is supplementing public key to get to the base figure

and restore encrypted information to Normal before encryption , and

this is a key characteristic of all people from other users and serve as

an electronic identity enables the owner of any decryption encrypted

information sent to him on the basis of the public key so you must keep

the private key.

11

Example of public key

In this example it is used by the public key encryption without the

private key in the encryption and decryption process

12

Example of public and private key

In this example is the use of encryption

by the public and private key where

the public key for all seen while the private

key is not seen.

13

Example of public and private key

In this example encryption process is done by the public key is not

decryption only by the private key using the public key.

14

In this slide we have talked about the subject of encryption in general

and explain the tools used in encryption ..

In the (L02)we will talk about the types of

encryption depending on the type of the key And some of the things.

15

Thanks for watching

16