1. Crypto in information security
Elmira ebrahimi, nazanin bayati, mona porbidei, shaghayegh arabnia
Teacher:ms.raeisian
Fall2015
Shariaty technical college

3. Introduction Developing in computer network Secure data????
Crypto via key
The Roman Empire
Most users, especially "encrypt information, Governments and military users

4. Information security
The protection of information and information systems from unauthorized activities
reach out, Disclosure, read, copy or record, manipulate, change, wreck.

5. Information security
Significant impact on the privacy of information security
Fields can work:
Securing networks and Infrastructure
securing applications and data bases
security testing
auditing and information systems program review
Planning the continuation of trade and reviews of electronic crimes, etc.

6. Base concepts
As the definition of information security, privacy, integrity means and availability information from unauthorized individuals

7. "Availability"
"integrity“
"Confidentiality"

8. availability The information should be when needed
by authorized persons are available

9. integrity
Integrity means that the data will prevent unauthorized change
detection and change the information in the event of unauthorized
tampering

10. Confidentiality
means that prevent information disclosure to unauthorized individuals
In credit card, card number is encrypted
Privacy breach
Like s.o. look at your data or send your data by mobile

11. Access control To secure information Limited to authorized people
Higher secure higher mechanism
Mechanism use authorization

12. authorization
What u are?
What u have?
What u know?

13. Science of Encryption
Encryption
Decryption

14. Science of encryption The science of codes and passwords
Need to prove the identity of the sender and the recipient
The message In the meantime
Should not change the content of the message to make sure

15. Encryption The operational initial data using an algorithm and a key
becomes a non-understandable text
no access to key, access to information from the encrypted text is impossible

16. decryption A device or program
that encrypted data returns to the first State
The change of non-readable codes to text readable

17. Applications of cryptography
Credit card information
The issue of membership in the forums
Private information
Details of the personal information
Sensitive information in an organization
Information relating to bank accounts

18. Crypto Cryptography  making “secret codes”
Cryptanalysis  breaking “secret codes”
Crypto  all of the above (and more) 17

19. Definitions of cryptography
(plaintext)
(Ciphertext)
(key) 18

20. Algorithms Basic assumption This is known as Kerckhoffs’ Principle
The system is completely known to the attacker
Only the key is secret
That is, crypto algorithms are not secret
This is known as Kerckhoffs’ Principle
Why do we make this assumption? 19

21. History 20

22. Simple Substitution Ciphertext: Khoor Jxbv Shift by 3
Plaintext HELLO GUYS
Key: a b c d e f g h i j k l m n o p q r s t u v w x y D E F G H I J K L M N O P Q R S T U V W X Y Z A B z C
Plaintext
Ciphertext
Ciphertext:
Khoor Jxbv
Shift by 3 21

23. Caesar’s cipher 22

24. Double Transposition 23

25. One-time Pad: Encryption
e=000 h=001 i=010 k=011 l=100 r=101 s=110 t=111 24

26. Taxonomy of Cryptography
Symmetric Key
Same key for encryption and decryption
Two types: Stream ciphers _ like a one-time pad, Block ciphers
Public Key (or asymmetric crypto)
Two keys, one for encryption (public), and one for decryption (private)
Also, digital signatures  nothing comparable in symmetric key crypto
Hash algorithms
Sometimes viewed as “one way” crypto 25

27. Symmetric Key Crypto Stream Ciphers
Once upon a time, the king of crypto
Today, not as popular as block ciphers
A5/1
Based on shift registers
Used in GSM mobile phone system 26

28. A5/1 maj(x8, y10, z10)     X Y Z 27 x0 x1 x2 x3 x4 x5 x6 x7 x8 x9

29. Block Ciphers Plaintext and ciphertext consist of fixed-sized blocks
Ciphertext obtained from plaintext by iterating a round function
Input to round function consists of key and the output of previous round
Usually implemented in software
Data Encryption Standard(DES)
Advanced Encryption Standard(AES) 28

30. Public Key Cryptography
Two keys
Sender uses recipient’s public key to encrypt
Recipient uses private key to decrypt
Based on “trap door one way function”
RSA is the gold standard in public key crypto 29

31. Hash Function Crypto hash function h(x) must provide
Compression output length is small
Efficiency h(x) easy to compute for any x
One-way given a value y it is infeasible to find an x such that h(x) = y 30

32. Visual Cryptography If a pixel is black, randomly choose c or d
If a pixel is white, randomly choose a or b for Alice’s/Bob’s shares
If a pixel is black, randomly choose c or d
no info from one share 31

33. منابع http://wikipedia.org/wiki/(computer_security)
Wikipedia
hit.mums.ac.ir

34. Question ??

35. Thanks For Listening