1. Institute of Information Technology &
Management
presentation
On
Cryptography
Submitted to:- Submitted by:-
D.D Shrivastava Sir Suraj Shukla
Dept cs & it 0915IT091060
IT 3rd year

2. What is Cryptography
• Cryptography is the science of encrypting and
decrypting written communication. It comes from the
Greek word “kryptos ,” meaning hidden, and “graphia
,” meaning writing.
• Cryptography is a method of storing and transmitting
data in a form that only those it is intended for can
read and process. It is a science of protecting
information by encoding it into an unreadable format.
Cryptography is an effective way of protecting
sensitive information as it is stored on media or
transmitted through network communication paths

3. History of Cryptography
• Cryptography has roots that began around 2000
B.C. in Egypt when hieroglyphics were used to
decorate tombs to tell the story of the life of the
deceased.
• A Hebrew cryptographic method required the
alphabet to be flipped so that each letter in the
original alphabet is mapped to a different letter
in the flipped alphabet. The encryption method
was called atbash.
• ABCDEFGHI JK LMNOPQ R STU VW XYZ
• ZYXWVUTSR QP ONMLKJ I HGF ED CBA
• Security= hvxfirgb

4. Continue…
Around 400 B.C., the Spartans used a system of encrypting information by
writing a message on a sheet of papyrus, which was wrapped around a staff.

5. Continue…
• During World War II, simplistic encryption
device called Enigma machine used for
tactical communication

6. Cryptosystem Services
• Confidentiality
• Integrity
• Authenticity
• Nonrepudiation
• Access Control

7. Keyspace
• An algorithm contains a keyspace, which is a
range of values that can be used to construct a
key. The key is made up of random values
within the keyspace range. The larger the
keyspace, the more available values can be
used to represent different keys, and the more
random the keys are, the harder it is for
intruders to figure them out.

8. Generation of key

9. Types of Cryptography
• Stream-based Ciphers-a stream cipher treats the
message as a stream of bits or bytes and performs
mathematical functions on them individually.
• Block Ciphers- When a block cipher algorithm is
used for encryption and decryption purposes, the
message is divided into blocks of bits. These blocks
are then put through substitution , transposition ,
and other mathematical functions.

12. Cryptographic Methods
• Symmetric
– Same key for encryption and decryption
– Key distribution problem
• Asymmetric
– Mathematically related key pairs for encryption
and decryption
– Public and private keys
• Hybrid Encryption Methods(Public Key Cryptography)

13. Symmetric Algorithms
• Data Encryption Standard (DES)
– Modes: ECB, CBC, CFB, OFB, CM
• Triple-DES (3DES)
• Advanced Encryption Standard (AES)
• International Data Encryption Algorithm
(IDEA)
• Blowfish

14. Example of Symmetric algorithms

15. Strength and Weakness
• Strengths
• Much faster than asymmetric systems
• Hard to break if using a large key size
• Weaknesses
• Key distribution It requires a secure
mechanism to deliver keys properly.
• Limited security It can provide
confidentiality, but not authenticity.

16. Asymmetric Algorithms
• RSA(Ron Rivest, Adi Shamir, and Leonard Adleman)
• El Gamal
• Elliptic Curve Cryptography (ECC)

17. Example of Asymmetric algorithms

18. Strength and Weakness
• Strengths
• Better key distribution than symmetric
systems
• Better scalability than symmetric systems
• Can provide confidentiality, authentication,
and nonrepudiation
• Weaknesses
• Works much slower than symmetric systems

19. Hybrid Encryption
In the hybrid approach, the two different
approaches are used in a complementary
manner, with each performing a different
function. A symmetric algorithm creates keys
that are used for encrypting bulk data and an
asymmetric algorithm creates keys that are
used for automated key distribution.

20. Example of Hybrid Encryption

21. This is all about Cryptography
THANK YOU
Any Queries