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ECE509 Cyber Security : Concept, Theory, and Practice

ECE509 Cyber Security : Concept, Theory, and Practice. Key Management Spring 2014. Key Management. addresses key distribution problems Two issues are handled distribution of public keys using public-key encryption to distribute secret keys. Distribution of Public Keys.

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ECE509 Cyber Security : Concept, Theory, and Practice

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  1. ECE509 Cyber Security :Concept, Theory, and Practice Key Management Spring 2014

  2. Key Management • addresses key distribution problems • Two issues are handled • distribution of public keys • using public-key encryption to distribute secret keys

  3. Distribution of Public Keys • Public announcement • Publicly available directory • Public-key authority • Public-key certificates

  4. Public Announcement • Users distribute public keys to recipients • Problems: • Authentication: anyone can create a key claiming to be someone else

  5. Public-Key Directory • Registering keys to a public directory • Required Properties: • Continuous Update • Authentication before adding or changing keys • Identification {ID, public-key} entry • Allow to change key at any time • API to access the directory • Problems: • Tampering or forgery

  6. Public-Key Authority • This is an improvement on the public key-directory. It constricts the access to the distribution of public keys. • Users access in real-time the directory and obtain the public keys by securely interacting with it and by using the directory’s public key.

  7. Public-Key Certificates • Similar to the Public-Key Authority but not in real-time. It uses certificates to allow public key exchange. The authority for certificates is called Certificate Authority(CA). • A certificate is binds an identity to a public key. It may also have other information. • The certificate can be checked by any one who has the public key of the CA.

  8. Public-Key Distribution Methods • They are used to obtain public-key • The rarely are used for encryption because public-key algorithms are slow • Symmetric key encryption are used to protect message contents. And those are changed based on the concept of sessions.

  9. Simple Secret Key Distribution • Merklein 1979 • Alice generates a new temporary public key pair • Alice sends Bob the public key and its identity • Bob generates a session key K sends it to Alice encrypted using the supplied public key • Alice decrypts the session key and both use • Problem: • The adversary can intercept and impersonate any of the participants.

  10. Diffie-Hellman Key Exchange • The first public-key technique that was proposed by Diffie & Hellman in 1976. • It is a very practical method for public exchange of a secret key • It is commercially used

  11. Diffie-Hellman Key Exchange • It is used for public-key distribution • The value of the key depends on the participants • It is based on exponentiation in a Galois field (modulo a prime or a polynomial) • It is depends on time and on the difficulty of computing discrete logarithms

  12. Source: [ https://www.youtube.com/watch?v=3QnD2c4Xovk ]

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