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Unformatted text preview: Introduction Public Key Cryptography Cryptography and Protocols Andrei Bulatov Cryptography and Protocols Public Key Cryptography 142 Asymmetric Encryption Schemes Main idea: Use two keys, public and private Everyone can encrypt, but to decrypt one needs the private key Useful if we need to communicate with someone we dont have any preliminary agreements Usually slower and more expensive than private cryptography This defines usual applications: key distribution digital signatures Cryptography and Protocols Public Key Cryptography 143 Asymmetric Encryption Schemes (cntd) Definition An asymmetric encryption scheme (AES) is a triple of algorithms (K,E,D): keys: (e,d) e is a public encryption key d is a private decryption key encryption:  decryption: C P E e = ) ( C P D d = ) ( Cryptography and Protocols Public Key Cryptography 144 Trapdoor Functions Requirement to a AES: it has to be a trapdoor function: All algorithms are polynomial time (efficient) K: is a randomized algorithm : is a permutation on some set...
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This note was uploaded on 03/05/2012 for the course CMPT 404 taught by Professor Andreia.bulatov during the Spring '12 term at Simon Fraser.
 Spring '12
 AndreiA.Bulatov

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