L03_publickeycrypto

# One should algorithms one avoid using public key

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Unformatted text preview: an secret key ones. One should algorithms One avoid using public key algorithms to encrypt large amount of data (long messages) (long Use Public-key encryption to “seal” a digital envelope The sender picks a “secret” Session Key to encrypt the long message The using a secret key algorithm, e.g. AES. using By encrypting the session key with the Recipient’s public key, the By session key can be delivered securely to the recipient without any presession shared secret between the 2 parties Conversely, we can consider this as doing a secure session-key Conversely, exchange using public key encryption exchange History of Public Key Cryptography in “public” world Diffie was a graduate student in Stanford, working with Prof. Hellman on Diffie solving the “key distribution problem”. solving They proposed the concept of a “Public-Key Cryptosystem” (PKC). (This They concept remarkable idea developed jointly with Merkle.) which can: remarkable solve the key distribution problem of a symmetric key system and Even more amazingly, introduce the notion of digital signature However, they were unable to find the necessary functions to realize such a However, were system, namely, to find a pair of functions D( ) and E( ) such that: system, D(E(m)) = E(D(m)) = m and D( ) can be kept secret while E( ) is known to the public E( It is impossible to derive D( ) by knowing E( ) It D( E( Instead, they were able to find a way for communication parties to establish Instead, a shared secret via open communications only shared => This is the Diffie-Hellman Key exchange algorithm => The Beginning of Public Key Cryptography in “public” world (cont’d) Diffie and Hellman published their ideas and findings in “New Diffie Directions in Cryptography” Nov ’76, together with the open problem of realizing PKC of Ron Rivest saw Diffie and Hellman’s paper and was intrigued by it. Ron He enlisted the help of Shamir and Adleman, all from MIT, to work on the open problem and came up with the solution in 1977 --- this is the RSA algorithm RSA Diffie, Hellman, Merkle, Rivest, Shamir, Adleman were commonly Diffie,...
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