Oblivious pseudorandom function: Difference between revisions

Revision as of 01:00, 23 February 2025

Revision as of 01:01, 23 February 2025

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If the secret key used in the OPRF is high-entropy, then the output of the OPRF will also be high-entropy. This thereby solves the problem of the password being low-entropy, and therefore vulnerable to [[Password cracking|cracking]] via [[brute-force attack|brute force]].

This technique is called ''Password-Hardeningpassword hardening''.<ref>{{cite book |last1=Ford |first1=W. |last2=Kaliski |first2=B. S. |chapter=Server-assisted generation of a strong secret from a password |title=Proceedings IEEE 9th International Workshops on Enabling Technologies: Infrastructure for Collaborative Enterprises (WET ICE 2000)|date=2000 |pages=176–180 |doi=10.1109/ENABL.2000.883724 |isbn=0-7695-0798-0 |s2cid=1977743 |chapter-url=https://ieeexplore.ieee.org/document/883724}}</ref> It fills a similar purpose as [[key stretching]], but password- hardening adds significantly more entropy.

Further, since each attempt at guessing a password that is hardened in this way requires interaction with a server, it prevents an [[offline attack]], and thus enables the user or system administrator to be alerted to any password-cracking attempt.