{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/89129"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/89129","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Cryptographic agents","abstract":"Over the last decade or so, thanks to remarkable breakthroughs in cryptographic techniques, a wave of ''cryptographic objects'' -- identity-based encryption, fully-homomorphic encryption, functional encryption, and most recently, various forms of obfuscation -- have opened up exciting new possibilities for computing on encrypted data. Initial foundational results on this front consisted of strong impossibility results. Breakthrough constructions, as they emerged, often used specialized security definitions which avoided such impossibility results. However, as these objects and their constructions have become numerous and complex, often building on each other, the connections among these disparate cryptographic objects, and among their various security definitions, have become increasingly confusing. The goal of this work is to provide a clean and unifying framework for diverse cryptographic objects and their various security definitions, equipped with powerful 'reduction' and 'composition' theorems. We model the functionality desired from a cryptographic object via a 'schema' in an ideal world. Our new security definition, indistinguishability preservation, is parametrized by a family of 'test' functions. We say that a scheme securely implements a schema against a test family in the real world if for every test in the family, if test is able to hide some bit of information from all adversaries in the ideal world, then this bit should be hidden in the real world too. By choosing test families appropriately, we are able to place known security definitions (along with new ones) for a given object on the same canvas, enabling comparative analysis. Next, we explore the implications of a meaningful relaxation of our security definition, the one obtained by considering all-powerful adversaries in the ideal world. Thanks to our framework, we are not only able to substantially generalize known results connecting two important flavors of security definitions (simulation and indistinguishability) in cryptography under this relaxation, but significantly simplify them too. We also initiate a systematic study of the security of fundamental cryptographic primitives like public-key encryption under a new class of attacks that had not been considered so far in the literature. Once again, owing to the flexibility of our framework, we are able to model such attacks, along with existing ones, in a clean and satisfactory way.","abstract_html":"Over the last decade or so, thanks to remarkable breakthroughs in cryptographic techniques, a wave of ''cryptographic objects'' -- identity-based encryption, fully-homomorphic encryption, functional encryption, and most recently, various forms of obfuscation -- have opened up exciting new possibilities for computing on encrypted data. Initial foundational results on this front consisted of strong impossibility results. Breakthrough constructions, as they emerged, often used specialized security definitions which avoided such impossibility results. However, as these objects and their constructions have become numerous and complex, often building on each other, the connections among these disparate cryptographic objects, and among their various security definitions, have become increasingly confusing. The goal of this work is to provide a clean and unifying framework for diverse cryptographic objects and their various security definitions, equipped with powerful 'reduction' and 'composition' theorems. We model the functionality desired from a cryptographic object via a 'schema' in an ideal world. Our new security definition, indistinguishability preservation, is parametrized by a family of 'test' functions. We say that a scheme securely implements a schema against a test family in the real world if for every test in the family, if test is able to hide some bit of information from all adversaries in the ideal world, then this bit should be hidden in the real world too. By choosing test families appropriately, we are able to place known security definitions (along with new ones) for a given object on the same canvas, enabling comparative analysis. Next, we explore the implications of a meaningful relaxation of our security definition, the one obtained by considering all-powerful adversaries in the ideal world. Thanks to our framework, we are not only able to substantially generalize known results connecting two important flavors of security definitions (simulation and indistinguishability) in cryptography under this relaxation, but significantly simplify them too. We also initiate a systematic study of the security of fundamental cryptographic primitives like public-key encryption under a new class of attacks that had not been considered so far in the literature. Once again, owing to the flexibility of our framework, we are able to model such attacks, along with existing ones, in a clean and satisfactory way.","abstract_has_math":false,"creators":["Agrawal, Shashank"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Computer Science","degree_department":null,"school":null,"contributors":["Prabhakaran, Manoj","Gunter, Carl","Borisov, Nikita","Vaidya, Nitin","Vaikuntanathan, Vinod"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2016,"date_issued":"2016-03-02T20:23:49Z","date_published":"2016-03-02T20:23:49Z","updated_at":"2026-07-22T22:26:32Z","subjects":["cryptography","security framework","functional encryption","obfuscation"],"languages":["en"],"rights":["Copyright 2015 Shashank Agrawal"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/89129","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Prabhakaran, Manoj","Gunter, Carl","Borisov, Nikita","Vaidya, Nitin","Vaikuntanathan, Vinod"]},{"key":"dc:creator","label":"Author","values":["Agrawal, Shashank"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2016-03-02T20:23:49Z","2018-03-03T10:15:31Z","2015-12-01","2015-12"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Computer Science"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["cryptography","security framework","functional encryption","obfuscation"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2015 Shashank Agrawal"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/89129"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Over the last decade or so, thanks to remarkable breakthroughs in cryptographic techniques, a wave of ''cryptographic objects'' -- identity-based encryption, fully-homomorphic encryption, functional encryption, and most recently, various forms of obfuscation -- have opened up exciting new possibilities for computing on encrypted data. Initial foundational results on this front consisted of strong impossibility results. Breakthrough constructions, as they emerged, often used specialized security definitions which avoided such impossibility results. However, as these objects and their constructions have become numerous and complex, often building on each other, the connections among these disparate cryptographic objects, and among their various security definitions, have become increasingly confusing. The goal of this work is to provide a clean and unifying framework for diverse cryptographic objects and their various security definitions, equipped with powerful 'reduction' and 'composition' theorems. We model the functionality desired from a cryptographic object via a 'schema' in an ideal world. Our new security definition, indistinguishability preservation, is parametrized by a family of 'test' functions. We say that a scheme securely implements a schema against a test family in the real world if for every test in the family, if test is able to hide some bit of information from all adversaries in the ideal world, then this bit should be hidden in the real world too. By choosing test families appropriately, we are able to place known security definitions (along with new ones) for a given object on the same canvas, enabling comparative analysis. Next, we explore the implications of a meaningful relaxation of our security definition, the one obtained by considering all-powerful adversaries in the ideal world. Thanks to our framework, we are not only able to substantially generalize known results connecting two important flavors of security definitions (simulation and indistinguishability) in cryptography under this relaxation, but significantly simplify them too. We also initiate a systematic study of the security of fundamental cryptographic primitives like public-key encryption under a new class of attacks that had not been considered so far in the literature. Once again, owing to the flexibility of our framework, we are able to model such attacks, along with existing ones, in a clean and satisfactory way.","Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2017-12-01","The student, Shashank Agrawal, accepted the attached license on 2015-11-29 at 11:48.","The student, Shashank Agrawal, submitted this Dissertation for approval on 2015-11-29 at 12:26.","This Dissertation was approved for publication on 2015-12-01 at 16:15.","DSpace SAF Submission Ingestion Package generated from Vireo submission #8857 on 2016-03-02 at 14:06:40","Made available in DSpace on 2016-03-02T20:23:49Z (GMT). No. of bitstreams: 3 AGRAWAL-DISSERTATION-2015.pdf: 856650 bytes, checksum: 5d8562d3399ad332ece1cb3250da151a (MD5) thesis-files.zip: 2679642 bytes, checksum: 7b3bb086b4e37b04099f95cb4051baee (MD5) LICENSE.txt: 4213 bytes, checksum: 385ad8e9ee4b4aa7d3b2f0b57175b6ab (MD5) Previous issue date: 2015-12-01","Embargo set by: Seth Robbins for item 91331 Lift date: 2018-03-02T20:24:31Z Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD system","U of I Only Restriction Lifted for Item 91331 on 2018-03-03T10:15:31Z."]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Cryptographic agents"]}]}],"canonical_facts":{"dc:contributor":["Prabhakaran, Manoj","Gunter, Carl","Borisov, Nikita","Vaidya, Nitin","Vaikuntanathan, Vinod"],"dc:creator":["Agrawal, Shashank"],"dc:date":["2016-03-02T20:23:49Z","2018-03-03T10:15:31Z","2015-12-01","2015-12"],"dc:description":["Over the last decade or so, thanks to remarkable breakthroughs in cryptographic techniques, a wave of ''cryptographic objects'' -- identity-based encryption, fully-homomorphic encryption, functional encryption, and most recently, various forms of obfuscation -- have opened up exciting new possibilities for computing on encrypted data. Initial foundational results on this front consisted of strong impossibility results. Breakthrough constructions, as they emerged, often used specialized security definitions which avoided such impossibility results. However, as these objects and their constructions have become numerous and complex, often building on each other, the connections among these disparate cryptographic objects, and among their various security definitions, have become increasingly confusing. The goal of this work is to provide a clean and unifying framework for diverse cryptographic objects and their various security definitions, equipped with powerful 'reduction' and 'composition' theorems. We model the functionality desired from a cryptographic object via a 'schema' in an ideal world. Our new security definition, indistinguishability preservation, is parametrized by a family of 'test' functions. We say that a scheme securely implements a schema against a test family in the real world if for every test in the family, if test is able to hide some bit of information from all adversaries in the ideal world, then this bit should be hidden in the real world too. By choosing test families appropriately, we are able to place known security definitions (along with new ones) for a given object on the same canvas, enabling comparative analysis. Next, we explore the implications of a meaningful relaxation of our security definition, the one obtained by considering all-powerful adversaries in the ideal world. Thanks to our framework, we are not only able to substantially generalize known results connecting two important flavors of security definitions (simulation and indistinguishability) in cryptography under this relaxation, but significantly simplify them too. We also initiate a systematic study of the security of fundamental cryptographic primitives like public-key encryption under a new class of attacks that had not been considered so far in the literature. Once again, owing to the flexibility of our framework, we are able to model such attacks, along with existing ones, in a clean and satisfactory way.","Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2017-12-01","The student, Shashank Agrawal, accepted the attached license on 2015-11-29 at 11:48.","The student, Shashank Agrawal, submitted this Dissertation for approval on 2015-11-29 at 12:26.","This Dissertation was approved for publication on 2015-12-01 at 16:15.","DSpace SAF Submission Ingestion Package generated from Vireo submission #8857 on 2016-03-02 at 14:06:40","Made available in DSpace on 2016-03-02T20:23:49Z (GMT). No. of bitstreams: 3 AGRAWAL-DISSERTATION-2015.pdf: 856650 bytes, checksum: 5d8562d3399ad332ece1cb3250da151a (MD5) thesis-files.zip: 2679642 bytes, checksum: 7b3bb086b4e37b04099f95cb4051baee (MD5) LICENSE.txt: 4213 bytes, checksum: 385ad8e9ee4b4aa7d3b2f0b57175b6ab (MD5) Previous issue date: 2015-12-01","Embargo set by: Seth Robbins for item 91331 Lift date: 2018-03-02T20:24:31Z Reason: Author requested U of Illinois access only (OA after 2yrs) in Vireo ETD system","U of I Only Restriction Lifted for Item 91331 on 2018-03-03T10:15:31Z."],"dc:format":["application/pdf"],"dc:identifier":["http://hdl.handle.net/2142/89129"],"dc:language":["en"],"dc:rights":["Copyright 2015 Shashank Agrawal"],"dc:subject":["cryptography","security framework","functional encryption","obfuscation"],"dc:title":["Cryptographic agents"],"dc:type":["text"],"thesis:degree_discipline":["Computer Science"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:26:32Z"}