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Unformatted text preview: 09/28/10 CSE565: S. Upadhyaya Lec 9.1 UB Fall 2010 CSE565: S. Upadhyaya Lec 9.1 CSE565: Computer Security Lecture 9 Public Key Cryptography and RSA Shambhu Upadhyaya Computer Science & Eng. University at Buffalo Buffalo, New York 14260 09/28/10 UB Fall 2010 CSE565: S. Upadhyaya Lec 9.2 Acknowledgments Material for some slides is drawn from Lawrie Brown’s slides 09/28/10 UB Fall 2010 CSE565: S. Upadhyaya Lec 9.3 Motivation (1) Public Key Cryptography Perhaps the only true revolution in the history of cryptography Based on mathematical functions unlike conventional ones DES is a significant advance by IBM, but based on substitution and permutation PKEs are asymmetric techniques  use two separate keys Enhance confidentiality, key distribution and authentication 09/28/10 UB Fall 2010 CSE565: S. Upadhyaya Lec 9.4 Motivation (2) Addresses two key issues: Key distribution – how to have secure communications in general without having to trust a KDC with your key Digital signatures – how to verify a message comes intact from the claimed sender Public invention due to Whitfield Diffie & Martin Hellman at Stanford in 1976 Known earlier in classified community 09/28/10 UB Fall 2010 CSE565: S. Upadhyaya Lec 9.5 Advantages Advantages of PKE Anyone can send a secret message to a user with fewer keys Conventional systems require a separate key for every pair of users Illustration A,B,C want to set up communication channels in pairs Keys needed  kAB, kAC, kBC n user system requires n(n1)/2 keys 09/28/10 UB Fall 2010 CSE565: S. Upadhyaya Lec 9.6 PublicKey Characteristics (1) PublicKey algorithms rely on two keys with the characteristics that it is: Computationally infeasible to find decryption key knowing only algorithm & encryption key Computationally easy to en/decrypt messages when the relevant (en/decrypt) key is known Either of the two related keys can be used for encryption, with the other used for decryption (in some schemes) 09/28/10 UB Fall 2010 CSE565: S. Upadhyaya Lec 9.7 PKE Characteristics (2) Each user has two keys A public key and a private key...
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This note was uploaded on 10/12/2010 for the course CSE 565 taught by Professor Shambhu during the Fall '09 term at SUNY Buffalo.
 Fall '09
 shambhu
 Computer Security

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