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
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
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
Continue…Around 400 B.C., the Spartans used a system of encrypting information bywriting a message on a sheet of papyrus, which was wrapped around a staff.
Continue…• During World War II, simplistic encryption device called Enigma machine used for tactical communication
Cryptosystem Services• Confidentiality• Integrity• Authenticity• Nonrepudiation• Access Control
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.
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.
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)
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
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.
Asymmetric Algorithms• RSA(Ron Rivest, Adi Shamir, and Leonard Adleman)• El Gamal• Elliptic Curve Cryptography (ECC)
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
Hybrid EncryptionIn the hybrid approach, the two differentapproaches are used in a complementarymanner, with each performing a differentfunction. A symmetric algorithm creates keysthat are used for encrypting bulk data and anasymmetric algorithm creates keys that areused for automated key distribution.