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how to provide security for network

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NETWORK SECURITY & CRYPTOGRAPHY P.HARISH REDDY VI th CSE

CONTENTS:

CONTENTS Basic Idea Encryption and decryption Strong cryptography How does cryptography work? Cryptographic Algorithms Conventional cryptography Public key cryptography Digital signatures Hash functions QUANTUM CRYPTOGRAPHY - Basic Ideas Uses of QUANTUM CRYPTOGRAPHY Eavesdropping MAN - IN THE - MIDDLE ATTACK Advantages and Disadvantages Conclusion

Network security problems :

Network security problems Privacy : Privacy means that the sender and the receiver expect the confidentiality. Data integrity : Ensure that data is not changed from source to destination Non-repudiation : the sender has strong evidence that the receiver has received the message, and the receiver has strong evidence of the sender identity

Basic Idea :

Basic Idea The goal of cryptography is to make it possible that two people to exchange a message in such a way that other people cannot understand. There is no end that number of ways this can be done, but here we will be concerned with the methods of altering the text in such a way that the recipient can undo the alteration and discover the original text.

Encryption and decryption :

Encryption and decryption Encryption and decryption Encryption and decryption Fig :-Encryption and decryption

Strong cryptography :

Strong cryptography Cryptographic strength is measured in the time and resources it would require to recover the plaintext. How difficult ?

How does cryptography work? :

How does cryptography work? A cryptographic algorithm works in Combination with a key—a word, number, or phrase—to encrypt the plaintext. The same plaintext encrypts to different cipher text with different keys. The security of encrypted data is entirely dependent on two things - strength of the cryptographic algorithm - the secrecy of the key

Cryptographic Algorithms :

Cryptographic Algorithms Conventional Cryptography (Symmetric algorithms, Private keys). 2. Public key Cryptography (Asymmetric algorithms, public keys). 3. Hash function algorithm.

Cryptographic implementation :

Cryptographic implementation Cryptographic algorithms can implemented either hardware or in software

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Conventional cryptography Fig:-Conventional cryptography

Public key cryptography :

Public key cryptography

Digital signatures :

Digital signatures

Hash functions :

Hash functions

QUANTUM CRYPTOGRAPHY - Basic Ideas :

QUANTUM CRYPTOGRAPHY - Basic Ideas Detection works only after the information was taken. Usually requires classical information channel for effective communication.

QUANTUM CRYPTOGRAPHY - Basic Ideas :

QUANTUM CRYPTOGRAPHY - Basic Ideas

Data Representation :

Data Representation Two bases are used: Vertical Diagonal

The Exchange :

The Exchange The Sequence of events: A generates random key and encoding basis. A sends the polarized photons to B. A announces the polarization for each bit. B generates random encoding basis. B measures photons with random basis. B announces which basis are the same as A’s. Finally, the matching bits are used as the key for a classical channel

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The Exchange

Sequential View :

Sequential View

Uses of QUANTUM CRYPTOGRAPHY:

Uses of QUANTUM CRYPTOGRAPHY Primarily used for key exchange for classical cryptography. Key doesn’t have any information value. The receiver knows if any parts of the key are intercepted. Key is random, if intercepted then just generates a new one.

Eavesdropping: :

Eavesdropping:

MAN - IN THE - MIDDLE ATTACK :

MAN - IN THE - MIDDLE ATTACK

Advantages and Disadvantages: :

Advantages and Disadvantages: Based on natural quantum laws Computational Complexity Expires. There is no expiration date on the security of QC messages. Perfect for public communication Easy to detect an eavesdropper. Severally limited by technology Practical systems are limited by distance. Photon emitters and detectors are far from perfect, causing a lot of errors. Most protocols require a classical channel.

Conclusion: :

Conclusion: The security field is a new, fast-moving career. A focus on security stabilizes course material, reduces worry about student hacking. Even though we are providing high security by cryptography there are many pitfalls in it also. Cryptography is one of the way to provide network security but it is not only the path to achieve network security. Emphasize the application of security tools.

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