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I want to implement top k multi keyword file retrieval using homomorphic encryption. Here vector space model is used for calculating scores and to provide rank of the file. tf-idf weighting scheme is used to calculate weight matrix for this application. For this calculation i want to use paillier encryption. How can i use this paillier.

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The answer may depend on your exact definitions of "homomorphic" and "malleable", but I'll give it a shot. Basically, homomorphic encryption denotes that, given encryptions $E_k(x)$ and $E_k(y)$ of some values $x$ and $y$, it is possible to obtain an encryption of $x\ast y$ under $k$ from $E_k(x)$ and $E_k(y)$, where $\ast$ is some binary operation, without ...

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This probably doesn't actually qualify as leveled-homomorphic, since it doesn't extend nicely. For integers $n$ and positive integers $m$, define $\operatorname{smod}$ ("signed mod" or "symmetric-ish mod") by $\;\;\;\;\; (q\hspace{-0.04 in}\cdot \hspace{-0.04 in}n)+r \: \operatorname{smod} \: m \;\; = \;\; r \;\;\;\;\;$ for integers $r$ such that $\;\; ... 1 Yes ElGamal and RSA (without padding) are both partially homomorphic (wrt. mulitiplication). I can not think of any applications that uses the homomorphic properties of these schemes in practice. However, in terms of efficiency they are probably about equal. Evaluating the homomorphism involves just one multiplication for RSA and two for ElGamal. As for ... 2 How about this: an electronic voting scheme. Votes are cast onto a publicly readable but append-only bulletin board as encryptions under the system public (Paillier) key. Anyone can homomorphically compute the sum of the cast votes. The vote admins each hold a share in the secret key; they must cooperate in order to decrypt anything. In this way, as long as ... 0 There is an auction system used every year by Danish sugar beet farmers to trade production rights. This system uses secure multiparty computation to keep the bids secret so that only the result of the auction is revealed. The system is described here https://eprint.iacr.org/2008/068 As far as I know it is the first real-world use of MPC. The company ... 2 IACR uses electronic, encrypted voting for their elections every year. They use Helios Sharemind has been used in a few applications (financial data analysis) CipherCloud claims to do a number of things on encrypted data. There was some discussion of their work on here that was partially removed due to a DMCA request. Skyhigh Networks does ... 0 For exponential ElGamal this is quite easy if all singe ciphertexts are public (you mentioned they are on a public bulletin board). Lets call$(c_1,c_2)=(g^my^r,g^r)$the ciphertext corresponding to the sum$m$of all single encrypted messages after your homomorphic summing (with$y=g^x\$ being the public key). The decrypting party simply provides a ...

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