Introduction to DECRYPTION , which is the basis for the security and protection of information, you will learn the meaning of encryption and decryption and encryption keys used in the examples.

1. Cryptography
L01- Introduction

2. outline
 Historically
 What is cryptography
 Cryptography goals
 Cryptography sections
● Encryption
● Decryption
 Cryptography keys and their importance
 Types of Cryptography keys
● public Key
● private key
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3. 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.
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4. 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.
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5. 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
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6. Cryptography goals 6
Confidentiality
Availability Integrity

7. 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:
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8. Cryptography sections
 Decryption :
It is the opposite of the encryption process is the conversion of non-
understood codes to understandable using Decryption algorithms
process.
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9. 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.
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10. 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.
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11. 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.
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12. 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
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13. 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.
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14. 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.
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15. 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.
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16. Thanks for watching
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