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# Cryptography

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### Cryptography

1. 1. CRYPTOGRAPHY
2. 2. CONTENTS• What is Cryptography ?• Types of Cryptographic Techniques• Why Different Encryption Techniques ?• Drawbacks of Classical Cryptography• Need for New Techniques• New Trends in Cryptography• Conclusion
3. 3. What is Cryptography ?• Cryptography is the practice and study of hiding information.• It is a branch of both mathematics and computer science , and is affiliated closely with information theory, computer security, and engineering.• Cryptography is used in applications present in technologically advanced societies.• Ex: ATM cards, computer passwords, and electronic commerce etc.
4. 4. Types of Cryptographic Techniques• They are categorized based on the number of keys that are employed for encryption and decryption.• The three types are :- • Secret Key Cryptography • Public Key Cryptography • Hash Functions
5. 5. Secret Key Cryptography• Secret-key Cryptography involves using the same key for encryption and decryption.• Key used for Encryption must be as long as the message.• The main disadvantages of Secret Key Cryptography is exchange of keys.
6. 6. Public Key Cryptography• Public-key cryptography requires two separate keys, one of which is secret and one of which is public.• In this public key is used for encryption and private key is used for decryption.
7. 7. Hash Functions•It does not use any key for encryption.•It uses a mathematical transformation to irreversibly "encrypt" information.•Here the message is converted into a fixed length hash value.
8. 8. Why Different Encryption Techniques ?•Hash Function are used for ensuring data integrity.•Secret key cryptography is ideally suitable for encrypting messages.•Public key cryptography is also used for encrypting messages but here differentkeys are used for encryption and decryption, so it is more secured than secretkey cryptography.
9. 9. Drawbacks of Classical Cryptography•Here the Encryption and Decryption Algorithms are publicly available.•The privacy of the data transmission depends only on secrecy of a key.•Thus if the key is revealed then the data can be compromised.
10. 10. Need for new Techniques•Today everything is on the internet.•Thus Security plays a vital role in maintaining data.•The older techniques are vulnerable to attacks .•So to keep the data secure new techniques are required which are notvulnerable.
11. 11. New Trends in Cryptography•The two new Technologies include : • Elliptic Curve Cryptography • Quantum Cryptography • Pairing based cryptography
12. 12. Elliptic Curve CryptographyElliptic Curve Cryptography was proposed in 1985 by Victor Miller.Two Points P and Q are given where Q is the public key.Consider an integer n such that P=nQ .An attacker might know P and Q but it is very difficult to find n which is the private key.
13. 13. Quantum cryptographyIt describes use of quantum mechanical effects to perform cryptographic tasksQuantum communication to securely exchange a keyQuantum computers can only break into such encryption schemes
14. 14. Pairing based cryptographyPairs elements of two groups to construct a hybrid cryptographic systemEg bilinear mappingUsing two or more vectors to yield a third vector to be used as key
15. 15. CONCLUSION