applied cryptography - protocols, algorithms, and source code in c

Designed by michael merritt 452 1076 453 it is so

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Unformatted text preview: two of them got together, they could correlate databases and figure out who voted for whom. Voting with a Single Central Facility A more complex protocol can be used to overcome the danger of collusion between the CLA and the CTF [1373]. This protocol is identical to the previous one, with two modifications: — The CLA and the CTF are one organization, and — ANDOS (see Section 4.13) is used to anonymously distribute validation numbers in step (2). Since the anonymous key distribution protocol prevents the CTF from knowing which voter got which validation number, there is no way for the CTF to correlate validation numbers with votes received. The CTF still has to be trusted not to give validation numbers to ineligible voters, though. You can also solve this problem with blind signatures. Improved Voting with a Single Central Facility This protocol also uses ANDOS [1175]. It satisfies all six requirements of a good voting protocol. It doesn’t satisfy the seventh requirement, but has two properties additional to the six listed at the beginning of the section: 7. A voter can change his mind (i.e., retract his vote and vote again) within a given period of time. 8. If a voter finds out that his vote is miscounted, he can identify and correct the problem without jeopardizing the secrecy of his ballot. Here’s the protocol: (1) The CTF publishes a list of all legitimate voters. (2) Within a specified deadline, each voter tells the CTF whether he intends to vote. (3) The CTF publishes a list of voters participating in the election. (4) Each voter receives an identification number, I, using an ANDOS protocol. (5) Each voter generates a public-key/private-key key pair: k, d. If v is the vote, he generates the following message and sends it to the CTF: I,Ek(I,v) This message must be sent anonymously. (6) The CTF acknowledges receipt of the vote by publishing: Ek(I,v) (7) Each voter sends the CTF: I,d (8) The CTF decrypts the votes. At the end of the election, it publishes the results of the election and, for ea...
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