... PRIVACY PRESERVING DATA MINING (Nghiên cu xây dng mt s gii pháp đm bo an toàn thông tin trong quá trình khai phá d liu) LUN ÁN TIN S TOÁN HC Hà Ni ... encryption depends onnew random values being used for each encryption. In the frequency miningprotocol, the xl, yl, pl, and qlare random values, and associated X and Y ,cannot be reused in ... Paillier cryptosystem [50] and then improvedby Damgard and Jurik [12].2.2.4. Variant ElGamal CryptosystemOur protocols in Chapter 3 and 4 are based on the standard variant ofthe ElGamal encryption...