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Nov 02, 2014




  • 1. Institute of Information Technology &ManagementpresentationOn Cryptography Submitted to:-Submitted by:- D.D Shrivastava Sir Suraj Shukla Dept cs & it0915IT091060 IT 3rd year

2. What is Cryptography Cryptography is the science of encrypting anddecrypting written communication. It comes from theGreek word kryptos , meaning hidden, and graphia, meaning writing. Cryptography is a method of storing and transmittingdata in a form that only those it is intended for canread and process. It is a science of protectinginformation by encoding it into an unreadable format.Cryptography is an effective way of protectingsensitive information as it is stored on media ortransmitted through network communication paths 3. History of Cryptography Cryptography has roots that began around 2000B.C. in Egypt when hieroglyphics were used todecorate tombs to tell the story of the life of thedeceased. A Hebrew cryptographic method required thealphabet to be flipped so that each letter in theoriginal alphabet is mapped to a different letterin the flipped alphabet. The encryption methodwas called atbash. ABCDEFGHI JK LMNOPQ R STU VW XYZ ZYXWVUTSR QP ONMLKJ I HGF ED CBA Security= hvxfirgb 4. ContinueAround 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. 5. Continue During World War II, simplistic encryptiondevice called Enigma machine used fortactical communication 6. Cryptosystem Services Confidentiality Integrity Authenticity Nonrepudiation Access Control 7. Keyspace An algorithm contains a keyspace, which is arange of values that can be used to construct akey. The key is made up of random valueswithin the keyspace range. The larger thekeyspace, the more available values can beused to represent different keys, and the morerandom the keys are, the harder it is forintruders to figure them out. 8. Generation of key 9. Types of Cryptography Stream-based Ciphers-a stream cipher treats themessage as a stream of bits or bytes and performsmathematical functions on them individually. Block Ciphers- When a block cipher algorithm isused for encryption and decryption purposes, themessage is divided into blocks of bits. These blocksare then put through substitution , transposition ,and other mathematical functions. 10. 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) 11. 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 12. Example of Symmetric algorithms 13. Strength and Weakness Strengths Much faster than asymmetric systems Hard to break if using a large key size Weaknesses Key distribution It requires a securemechanism to deliver keys properly. Limited security It can provideconfidentiality, but not authenticity. 14. Asymmetric Algorithms RSA(Ron Rivest, Adi Shamir, and Leonard Adleman) El Gamal Elliptic Curve Cryptography (ECC) 15. Example of Asymmetric algorithms 16. Strength and Weakness Strengths Better key distribution than symmetricsystems Better scalability than symmetric systems Can provide confidentiality, authentication,and nonrepudiation Weaknesses Works much slower than symmetric systems 17. 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. 18. Example of Hybrid Encryption 19. This is all about CryptographyTHANK YOUAny Queries