University of Kentucky UKnowledge University of Kentucky Doctoral Dissertations Graduate School 2011 CONSTRUCTION OF EFFICIENT AUTHENTICATION SCHEMES USING TRAPDOOR HASH FUNCTIONS Santosh Chandrasekhar University of Kentucky, [email protected] Right click to open a feedback form in a new tab to let us know how this document benefits ou.y Recommended Citation Chandrasekhar, Santosh, "CONSTRUCTION OF EFFICIENT AUTHENTICATION SCHEMES USING TRAPDOOR HASH FUNCTIONS" (2011). University of Kentucky Doctoral Dissertations. 162. https://uknowledge.uky.edu/gradschool_diss/162 This Dissertation is brought to you for free and open access by the Graduate School at UKnowledge. It has been accepted for inclusion in University of Kentucky Doctoral Dissertations by an authorized administrator of UKnowledge. For more information, please contact [email protected]. ABSTRACT OF DISSERTATION Santosh Chandrasekhar The Graduate School University of Kentucky 2011 CONSTRUCTION OF EFFICIENT AUTHENTICATION SCHEMES USING TRAPDOOR HASH FUNCTIONS ABSTRACT OF DISSERTATION A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the College of Engineering at the University of Kentucky By Santosh Chandrasekhar Lexington, Kentucky Director: Dr. Mukesh Singhal Lexington, Kentucky 2011 Copyright c Santosh Chandrasekhar 2011 ABSTRACT OF DISSERTATION CONSTRUCTION OF EFFICIENT AUTHENTICATION SCHEMES USING TRAPDOOR HASH FUNCTIONS In large-scale distributed systems, where adversarial attacks can have widespread impact, authentication provides protection from threats involving impersonation of entities and tampering of data. Practical solutions to authentication problems in distributed systems must meet specific constraints of the target system, and provide a reasonable balance between security and cost. The goal of this dissertation is to address the problem of building practical and efficient authentication mechanisms to secure distributed applications. This dissertation presents techniques to construct efficient digital signature schemes using trapdoor hash functions for various distributed applications. Trapdoor hash functions are collision-resistant hash functions associated with a secret trapdoor key that allows the key- holder to find collisions between hashes of different messages. The main contributions of this dissertation are as follows: 1. A common problem with conventional trapdoor hash functions is that revealing a collision producing message pair allows an entity to compute additional collisions without knowledge of the trapdoor key. To overcome this problem, we design an efficient trapdoor hash function that prevents all entities except the trapdoor key- holder from computing collisions regardless of whether collision producing message pairs are revealed by the key-holder. 2. We design a technique to construct efficient proxy signatures using trapdoor hash functions to authenticate and authorize agents acting on behalf of users in agent- based computing systems. Our technique provides agent authentication, assurance of agreement between delegator and agent, security without relying on secure communication channels and control over an agent’s capabilities. 3. We develop a trapdoor hash-based signature amortization technique for authenticating real-time, delay-sensitive streams. Our technique provides independent verifiability of blocks comprising a stream, minimizes sender-side and receiver-side delays, minimizes communication overhead, and avoids transmission of redundant information. 4. We demonstrate the practical efficacy of our trapdoor hash-based techniques for signature amortization and proxy signature construction by presenting discrete log- based instantiations of the generic techniques that are efficient to compute, and produce short signatures. Our detailed performance analyses demonstrate that the proposed schemes outperform existing schemes in computation cost and signature size. We also present proofs for security of the proposed discrete-log based instantiations against forgery attacks under the discrete- log assumption. Keywords: Authentication, digital signature, proxy signature, signature amortization, trapdoor hash functions Santosh Chandrasekhar May 3, 2011 CONSTRUCTION OF EFFICIENT AUTHENTICATION SCHEMES USING TRAPDOOR HASH FUNCTIONS By Santosh Chandrasekhar Dr. Mukesh Singhal Director of Dissertation Dr. Raphael A. Finkel Director of Graduate Studies May 3, 2011 RULES FOR THE USE OF DISSERTATIONS Unpublished dissertations submitted for the Doctor’s degree and deposited in the University of Kentucky Library are as a rule open for inspection, but are to be used only with due regard to the rights of the authors. Bibliographical references may be noted, but quotations or summaries of parts may be published only with the permission of the author, and with the usual scholarly acknowledgements. Extensive copying or publication of the dissertation in whole or in part also requires the consent of the Dean of the Graduate School of the University of Kentucky. A library that borrows this dissertation for use by its patrons is expected to secure the signature of each user. Name Date DISSERTATION Santosh Chandrasekhar The Graduate School University of Kentucky 2011 CONSTRUCTION OF EFFICIENT AUTHENTICATION SCHEMES USING TRAPDOOR HASH FUNCTIONS DISSERTATION A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the College of Engineering at the University of Kentucky By Santosh Chandrasekhar Lexington, Kentucky Director: Dr. Mukesh Singhal Lexington, Kentucky 2011 Copyright c Santosh Chandrasekhar 2011 DEDICATION Dedicated to my mother, Meenakshi Chandrasekhar, my father, Air Commodore C. D. Chandrasekhar (1944 - 1997) and my brother, Anand Chandrasekhar (1978 - 1996). ACKNOWLEDGMENTS I thank my advisor, Dr. Mukesh Singhal, for his guidance, support, counseling and technical advice throughout my graduate tenure. I thank Dr. Kenneth L. Calvert for his advice, support and constructive comments that helped me with both technical and personal challenges. Thanks to Dr. Dakshnamoorthy Manivannan, Dr. Uwe Nagel and Dr. Ting- Wen Wu for serving on my dissertation committee, and providing critical and constructive comments on my research work and dissertation. I thank Dr. Raphael A. Finkel for his support as the Director of Graduate Studies and for his corrections to my dissertation. I thank the remaining computer science faculty at the University of Kentucky for helping me build a strong academic foundation and prepare myself for future endeavors. I extend a special token of appreciation to Saikat Chakrabarti for his support, guidance and friendship that provided focus to my research work and helped shape my Ph.D tenure. Saikat, I thoroughly enjoyed our working relationship and I am glad for our continuing friendship. Thanks to Lei Zhu and Ashley Ritchie, for their support, advice and friendship during my Ph.D. tenure: it meant a lot to me and helped me get through some tough times. My mother’s blessings, her unconditional love and support, her immense sacrifices, her insightful advice and teachings are the reason for all my achievements. My father and brother showered me with love and affection, and instilled values in me that will always dictate my individuality. Their presence has been and always will be a guiding force behind shaping my life. iii Table of Contents Acknowledgment ..................................... iii ListofTables....................................... vi ListofFigures ...................................... vii Chapter1Introduction ............................... ... 1 1.1 Researchmotivation .............................. 3 1.2 Thesiscontributions .. .. .. .. .. .. .. .. 4 1.2.1 Building an efficient key-exposure-resistant trapdoor hash function . 5 1.2.2 Proxy signatures for authenticating agents in agent-based computing systems .................................. 6 1.2.3 A trapdoor hash based mechanism for stream authentication . 7 1.3 Thesisorganization.............................. 8 Chapter2Backgroundandrelatedwork . ...... 9 2.1 Cryptographic concepts and terminologies . ........ 9 2.2 Digitalsignatures............................... 13 2.2.1 Security of digital signatures . 13 2.2.2 Discrete log-based signatures . 14 2.2.3 Proxysignatures ............................. 17 2.2.4 Signature-based stream authentication techniques . .......... 18 2.3 Trapdoorhashfunctions . 19 2.3.1 Security properties of trapdoor hash functions . ....... 20 2.3.2 A discrete log-based trapdoor hash function . ...... 21 2.3.3 Applications of trapdoor hash functions . ..... 22 2.4 Summary ..................................... 23 Chapter 3 Building an efficient key-exposure-resistant trapdoor hash function . 25 3.1 Introduction.................................... 25 3.1.1 Problemstatement............................ 26 3.1.2 Contributions............................... 27 3.2 Definitions..................................... 28 3.3 Proposed key-exposure-free trapdoor hashing scheme, DL-MTH ........ 31 3.4 Analysis of the DL-MTH trapdoorhashingscheme . 33 3.4.1 Correctness ................................ 33 3.4.2 Security .................................. 33 3.4.3 Performance ............................... 35 3.5 Summary ..................................... 36 Chapter 4 Efficient proxy signatures based on trapdoor hash functions . 37 4.1 Introduction.................................... 37 4.1.1 Addressing security in agent-based systems . ...... 37 4.1.2