{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/109360"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/109360","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Proof-of-stake longest chain protocols: security vs predicability","abstract":"The Nakamoto longest chain protocol is remarkably simple and has been proven to provide security against any adversary with less than 50% of the total hashing power. Proof-of-stake (PoS) protocols are an energy-efficient alternative; however existing protocols adopting Nakamoto’s longest chain design achieve provable security only by allowing long-term predictability, subjecting the system to serious bribery attacks. In this thesis, we prove that a natural longest chain PoS protocol with predictability similar to that of Nakamoto’s PoW protocol can achieve security against any adversary with less than 1/(1 +e) fraction of the total stake. Moreover, we propose a new family of longest chain PoS protocols that achieve security against a 50% adversary, while only requiring short-term predictability. Our proofs present a new approach to analyzing the formal security of blockchains, based on a notion of Nakamoto block.","abstract_html":"The Nakamoto longest chain protocol is remarkably simple and has been proven to provide security against any adversary with less than 50% of the total hashing power. Proof-of-stake (PoS) protocols are an energy-efficient alternative; however existing protocols adopting Nakamoto’s longest chain design achieve provable security only by allowing long-term predictability, subjecting the system to serious bribery attacks. In this thesis, we prove that a natural longest chain PoS protocol with predictability similar to that of Nakamoto’s PoW protocol can achieve security against any adversary with less than 1/(1 +e) fraction of the total stake. Moreover, we propose a new family of longest chain PoS protocols that achieve security against a 50% adversary, while only requiring short-term predictability. Our proofs present a new approach to analyzing the formal security of blockchains, based on a notion of Nakamoto block.","abstract_has_math":false,"creators":["Wang, Xuechao"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"M.S.","degree_level":"Thesis","degree_discipline":"Electrical & Computer Engr","degree_department":null,"school":null,"contributors":["Viswanath, Pramod"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2021,"date_issued":"2021-03-05T21:36:57Z","date_published":"2021-03-05T21:36:57Z","updated_at":"2026-07-22T22:24:50Z","subjects":["Blockchain","Proof-of-stake"],"languages":["en"],"rights":["Copyright 2020 Xuechao Wang"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/109360","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Viswanath, Pramod"]},{"key":"dc:creator","label":"Author","values":["Wang, Xuechao"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2021-03-05T21:36:57Z","2020-11-16","2020-12"]},{"key":"dc:type","label":"Dc Type","values":["text","Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Electrical & Computer Engr"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis"]},{"key":"thesis:degree_name","label":"Degree Name","values":["M.S."]},{"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":["Blockchain","Proof-of-stake"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2020 Xuechao Wang"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/109360"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["The Nakamoto longest chain protocol is remarkably simple and has been proven to provide security against any adversary with less than 50% of the total hashing power. Proof-of-stake (PoS) protocols are an energy-efficient alternative; however existing protocols adopting Nakamoto’s longest chain design achieve provable security only by allowing long-term predictability, subjecting the system to serious bribery attacks. In this thesis, we prove that a natural longest chain PoS protocol with predictability similar to that of Nakamoto’s PoW protocol can achieve security against any adversary with less than 1/(1 +e) fraction of the total stake. Moreover, we propose a new family of longest chain PoS protocols that achieve security against a 50% adversary, while only requiring short-term predictability. Our proofs present a new approach to analyzing the formal security of blockchains, based on a notion of Nakamoto block.","Submission original under an indefinite embargo labeled 'Open Access'. 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In this thesis, we prove that a natural longest chain PoS protocol with predictability similar to that of Nakamoto’s PoW protocol can achieve security against any adversary with less than 1/(1 +e) fraction of the total stake. Moreover, we propose a new family of longest chain PoS protocols that achieve security against a 50% adversary, while only requiring short-term predictability. Our proofs present a new approach to analyzing the formal security of blockchains, based on a notion of Nakamoto block.","Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2021-03-04 without embargo terms","The student, Xuechao Wang, accepted the attached license on 2020-11-13 at 15:05.","The student, Xuechao Wang, submitted this Thesis for approval on 2020-11-13 at 15:22.","This Thesis was approved for publication on 2020-11-16 at 12:02.","DSpace SAF Submission Ingestion Package generated from Vireo submission #15884 on 2021-03-04 at 15:34:31","Made available in DSpace on 2021-03-05T21:36:57Z (GMT). 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