Unforgettable Fuzzy Extractor: Practical Construction and Security Model

Oleksandr Kurbatov; Dmytro Zakharov; Lasha Antadze; Victor Mashtalyar; Roman Skovron; Volodymyr Dubinin

Paper 2025/1799

Unforgettable Fuzzy Extractor: Practical Construction and Security Model

Oleksandr Kurbatov

, Rarimo

Dmytro Zakharov

, Distributed Lab

Lasha Antadze

, Rarimo

Victor Mashtalyar, Distributed Lab

Roman Skovron, Distributed Lab

Volodymyr Dubinin

, Distributed Lab

Abstract

Secure storage of private keys is a challenge. Seed phrases were introduced in 2013 to allow wallet owners to remember a secret without storing it electronically or writing it down. Still, very few people can remember even 12 random words. This paper proposes an alternative recovery option that utilizes lower-than-standard entropy secrets (such as passwords, biometrics, and object extractors). It can be used on its own (in combination with strong key derivation functions) or provide an additional backup option for the existing mnemonics. In this work, we investigate several aspects of secure key derivation: (1) how much entropy different sources can provide; (2) what is the preferred construction of the fuzzy extractor; (3) our key contributions in the selected approach; (4) the main security assumptions and properties of Unforgettable Fuzzy Extractor; (5) economic rationale for parameters (e.g., fuzzy vault size, additional PoW difficulty, secret length, cost of the attack) achieving the optimal solution from both security and time perspectives.

Metadata

Available format(s): PDF
Category: Applications
Publication info: Preprint.
Keywords: Fuzzy extractor Key derivation Security analysis
Contact author(s): ok @ distributedlab com
dmytro zakharov @ distributedlab com
lasha @ rarilabs com
victor mashtalyar @ distributedlab com
romanskovronn @ gmail com
dubinin @ distributedlab com
History: 2025-10-08: approved; 2025-10-01: received; See all versions
Short URL: https://ia.cr/2025/1799
License: CC BY

BibTeX

@misc{cryptoeprint:2025/1799,
      author = {Oleksandr Kurbatov and Dmytro Zakharov and Lasha Antadze and Victor Mashtalyar and Roman Skovron and Volodymyr Dubinin},
      title = {Unforgettable Fuzzy Extractor: Practical Construction and Security Model},
      howpublished = {Cryptology {ePrint} Archive, Paper 2025/1799},
      year = {2025},
      url = {https://eprint.iacr.org/2025/1799}
}