Lec6 - Key Agreement Protocol Sheng Zhong Public Key...

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Key Agreement Protocol Sheng Zhong
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Public Key Cryptosystem vs. Private Key Cryptosystem Public key Cryptosystem: +Allows sending message without a shared secret key. - Slower. Private key Cryptosystem: + Faster - Needs a shared secret key. Question: How to send a lot of data without a shared secret key?
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Hybrid Cryptosystem To send a lot of data without a shared secret key: Pick a key K at random. Use a public key cryptosystem to encrypt K under the receiver’s public key. Use a private key cryptosystem to encrypt data under key K.
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Advantages & Disadvantages of Hybrid Cryptosystem Advantages: Sending data without shared secret key. Faster than public key cryptosystem. Disadvantages: Ephemeral Key K is chosen solely by sender. If the receiver leaks her private key in the future, all old messages are subject to decryption by adversary.
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Key Exchange Protocol To avoid disadvantages of hybrid cryptosystem, we need a protocol: That sets up a shared key between two
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This note was uploaded on 09/27/2010 for the course CSE 664 taught by Professor Shengzhong during the Spring '10 term at SUNY Buffalo.

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Lec6 - Key Agreement Protocol Sheng Zhong Public Key...

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