Karim Eldefrawy

Cryptography, Cybersecurity, Privacy

Co-founder and CTO at Confidencial.io
2017-2021: SRI
2011-2016: HRL Laboratories
2006-2010: PhD@UC Irvine

Scientific curiosity

Scientific knowledge map · Paper #55

Communication-Efficient (Proactive) Secure Computation for Dynamic General Adversary Structures and Dynamic Groups

Karim Eldefrawy, Seoyeon Hwang, Rafail Ostrovsky, and Moti Yung

2020 · 12th Conference on Security and Cryptography for Networks (SCN)

  • Theory
  • protocol

What does the paper try to establish?

Can proactive secure multiparty computation remain communication-aware when corruption patterns are non-threshold, the general adversary structure changes over time, and parties join or leave?

What is the proposed answer?

The paper proactivizes both additive-sharing and monotone-span-program MPC, adds refresh, recovery, and redistribution for dynamic groups, and introduces secure conversions between the two representations so a system can select the one better suited to the current adversary structure.

Six dimensions, kept separate

The chart summarizes documented evidence and process. It is not a correctness probability, confidence score, or ranking, and no composite score is calculated.

The visual spider chart requires JavaScript. The complete values and rationales follow in text.

LowMediumHighN/A = not assessed

A smaller value means less documented support for that dimension, not that the paper is false or unimportant.

Epistemic evidence High

The complete source provides definitions, explicit protocol suites, communication bounds, ideal functionalities, and appendical proofs. It supplies theoretical rather than implementation evidence.

Two PMPC representations and conversion strategy Protocol specifications, simulators, and proofs Representation-size, scheduling, and communication boundaries
Auditability High

The full archive PDF and an author-uploaded copy expose assumptions and proofs, with an official DOI for publication identity. Direct local byte fixity could not be recorded because the archive blocked automated download.

Author-uploaded full text Official SCN publication identity
Production provenance Medium

Authors, venue, DOI, archive, and author-hosted full text are documented; revision history, contributor roles, and tool use are not.

Official SCN publication identity Problem, contributions, and structure-adaptive objective
External scrutiny Medium

SCN publication establishes venue review, but review reports, independent proof checks, and implementations are unavailable.

Official SCN publication identity
Reception Low

The dated exact-DOI OpenAlex record located 3 citations. Under the author-defined rule, 0 through 8 located citations is Low; counts are index- and date-dependent.

Dated citation-count snapshot
Contribution significance Medium

The paper addresses dynamic GAS, dynamic groups, and representation conversion in one PMPC framework, but this map does not independently establish priority or broad deployment impact.

Problem, contributions, and structure-adaptive objective Share conversion between additive and MSP representations

Assessment: Ai draft author review pending · 2026-07-11 · rubric 0.2. These dimensions describe documented support and process, not truth, correctness, or a universal ranking. No composite score is calculated.

Hierarchical knowledge map

Collapse a branch for a top-level reading, or follow its source links and child nodes to audit the evidence and boundaries underneath it.

paper

Communication-Efficient (Proactive) Secure Computation for Dynamic General Adversary Structures and Dynamic Groups

A formal protocol suite for proactive MPC under changing non-threshold adversary structures and participant sets, with conversions between additive and MSP secret-sharing representations.

Problem, contributions, and structure-adaptive objective
  1. scope Communication and phase model defined

    Parties use a synchronous network with authenticated broadcast and point-to-point channels. Operational and refresh phases alternate; a mobile adversary may change its corruption set subject to the current general adversary structure.

    Phase model, communication, and general adversary structures
  2. protocol Eight-operation dynamic PMPC framework specified

    Share, Reconstruct, Add, Multiply, Refresh, Recover, Redistribute, and Convert cover computation, proactive maintenance, membership change, and representation adaptation.

    Dynamic PMPC blueprint and design roadblocks Two PMPC representations and conversion strategy
    1. protocol

      Additive-sharing PMPC

      specified

      The additive realization distributes each summand to a designated holder set, uses information checking and dispute control against active faults, and adds new refresh, recover, and redistribution procedures.

      Additive-sharing PMPC protocols
    2. protocol

      MSP-based PMPC

      specified

      The monotone-span-program realization represents access structures with an MSP matrix and develops random-sharing, robust-resharing, recovery, refresh, and redistribution components around the base MPC protocol.

      MSP-based PMPC protocols
    3. protocol

      Bidirectional share conversion

      specified

      Conversion protocols transform an additive sharing into an MSP sharing and vice versa while preserving the secret, enabling protocol selection to follow the changing structure rather than remain fixed.

      Share conversion between additive and MSP representations
  3. claim group Security and efficiency claims formally analyzed

    The paper proves correctness and secrecy of the new maintenance and conversion subprotocols under their GAS conditions and gives separate communication bounds in terms of parties, maximal secrecy sets, MSP rows, field size, and checking parameters.

    Additive-sharing PMPC protocols MSP-based PMPC protocols Share conversion between additive and MSP representations Protocol specifications, simulators, and proofs
  4. evidence group

    Formal evidence

    proof documented

    The full source contains protocol pseudocode, correctness and secrecy statements, ideal-world formulations, simulators, and proofs for additive, MSP, and conversion components. This audit maps those obligations but does not independently verify every algebraic step.

    Protocol specifications, simulators, and proofs
  5. limitation group Boundaries material

    The results assume synchrony, authenticated broadcast, point-to-point channels, phase-based reboot and erasure behavior, and Q2-compatible structures. Communication can still be large because an adversary-structure description itself may be exponential in the party count.

    Phase model, communication, and general adversary structures Representation-size, scheduling, and communication boundaries
  6. scrutiny

    External scrutiny

    venue reviewed

    The paper appeared at SCN 2020. Review reports, independent proof audits, and reproductions are not represented.

    Official SCN publication identity

Source index

Locators state the depth of the current audit. PDF page numbers, where present, are one-based file pages; metadata-, summary-, and abstract-bounded records explicitly identify their limitations.

  1. Problem, contributions, and structure-adaptive objective Abstract and Section 1, PDF pages 1-3
  2. Author-uploaded full text ResearchGate public full-text record uploaded by an author
  3. Dynamic PMPC blueprint and design roadblocks Sections 3.1-3.2, PDF pages 4-6
  4. Phase model, communication, and general adversary structures Sections 4.1-4.3, PDF pages 6-8
  5. Two PMPC representations and conversion strategy Section 5 introduction, PDF pages 8-9
  6. Additive-sharing PMPC protocols Section 5.1, PDF pages 9-12
  7. MSP-based PMPC protocols Section 5.2, PDF pages 12-17
  8. Share conversion between additive and MSP representations Section 5.3, PDF pages 17-19
  9. Protocol specifications, simulators, and proofs Appendices B-F, PDF pages 24-41
  10. Representation-size, scheduling, and communication boundaries Sections 3.1-3.2 and 4.2, PDF pages 4-7
  11. Official SCN publication identity DOI 10.1007/978-3-030-57990-6_6
  12. Dated citation-count snapshot OpenAlex reported 3 citations when accessed 2026-07-11