Concept explainers
We describe a basis key exchange protocol using private key cryptography upon which more sophisticated protocols for key exchange are based. Encryption with protocol is done using a private key cryptosystem (such as AES) that is considered secure. The Protocol involves there parties, Alice and Bob, who wish to exchange a key, and a trusted third party Cathy. Assume that Alice has a secret key kAlicethat only she and Cathy know, and Bob has a secret key kBobwhich only he and Cathy know. The protocal has there steps:
- Alice sends the trusted third party Cathy the meassage “request a shared key with Bob” encrypted using Alice’s key kAlice.
- Cathy send back to Alice a key kAlice,Bob, which she generates, encrypted using the key kAlice,followed by this same key kAlice,Bob, encrypted using Bob’s key, kBob
- Alice sends to Bob the key kAlice,Bob,encrypted using kBob, known only to bob and to cathy
Explain why this protocol allows Alice and Bob to share the secret key kAlice,Bob,known only to them and to Cathy.
The Paillier cryptosystem is a public key cryptosystem described in 1999 by P. Paillier, used in some electronic voting systems. A public key (n,g) and a corresponding private key (pq) are created by randomly selecting primes p and q so that
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Discrete Mathematics and Its Applications ( 8th International Edition ) ISBN:9781260091991
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