14395

1334 دكتري

دكتري

مخابرات

اصفهان : دانشگاه صنعتي اصفهان

1397

دوازده، [۱۷۸]ص.: مصور، جدول، نمودار

مهدي برنجكوب، محمد دخيل عليان

علي فانيان

محمود سلماسي زاده، حميد ملا، مسعود عمومي

1397/12/06

كتابنامه

برق

مهندسي برق و كامپيوتر

1397/12/08

ID1334 دكتري

Privacy Preserving Digital Signatures Parvin Rastegari parvin rastegari@ec iut ac ir 28th January 2019 Department of Electrical and Computer EngineeringIsfahan University of Technology 84156 83111 Isfahan Iran1st Supervisor Dr Mehdi Berenjkoub brnjkb@cc iut ac ir 2nd Supervisor Dr Mohammad Dakhilalian mdalian@cc iut ac ir Advisor Dr Ali Fanian a fanian@cc iut ac ir Department Graduate Program Coordinator Dr Gholamreza Yousefi Isfahan University of Technology 84156 83111 Isfahan IranAbstractA digital signature is a well known primitive that provides integrity non repudiation and authenticity of mes sages in cryptographic protocols In an ordinary digital signature scheme the signer creates a signature whichis publicly verifiable by everyone Although this public verifiability of a traditional digital signature is usefulin many applications however there are also many scenarios in which the signer must be authenticaed withoutdisturbing his her privacy In this thesis we concentrated on two concepts of the privacy of the signer in digitalsignatures confidentiality and non transferability which are satisfied by signcryption and designated verifiersignature schemes respectively Consequently we solved some open problems and provided some contribu tions in these two fields It is important to note that we proved the security of all of our proposed schemes inthe standard model i e without the ideal assumptions Key WordsDigital Signature Privacy Confidentiality Signcryption Non Transferability Designated Verifier Signature Provable Security Standard Model IntroductionIn an ordinary digital signature the signer Alice creates a signature which is publicly veri fiable by everyone Rivest et al 1978 The privacy of Alice is not preserved in a traditionaldigital signature in two following senses The cofidentiality is not preserved as the message signed by Alice is not encrypted and is known to everyone A verifier Bob can convince any third party about Alice s signature by presenting her signature to the third party without the need of Alice s consent With regard to the first case one may think of encrypting the message and then creating asignature on the encrypted message However when both confidentiality and unforgeabilityare required at the same time a signcryption scheme offers a more efficient solution comparedto merely encrypting and signing the encrypted message consecutively Zheng 1997 With regard to the second case it must be noted that the public verifiability of digital sig natures is a useful and necessary property in some applications but it is not a desirable prop erty in some specific applications such as e votings e auctions and fair exchanges in whichintegrity and authenticity must be satisfied without disturbing the privacy of the signer In Jakobsson et al 1996 and Chaum 1996 the concept of designated verifier signature proof DVS DVP was proposed independently In a DVS scheme a signer Alice generates asignature which can only be verified by a designated verifier Bob Moreover Bob can not transfer his conviction about Alice s signature to any third party since he can produce

مهدي برنجكوب، محمد دخيل عليان

علي فانيان

محمود سلماسي زاده، حميد ملا، مسعود عمومي