Short Paper: Prefix Count Limits Can Increase First-Hit Discovery in Card Reissuance
Simulations show lowering card-prefix population caps can raise an attacker's chance of finding an active number.
This short paper examines card reissuance after a number is compromised, when an attacker may search for other active numbers sharing its prefix. For fixed search regions, exposure weights, and total activity, the authors derive when reducing the maximum prefix population increases the chance that a budgeted search finds an active number. In matched synthetic simulations over 50,000 candidates, targeted replacement met the count limit in every run but raised supplied 12-digit-prefix discovery relative to equal-volume random replacement in three of twelve settings.
- Models an attacker searching active card numbers that share a compromised prefix.
- Derives when a lower maximum prefix count raises first-hit discovery.
- Simulations cover 50,000 candidates with fixed regions, weights, and activity.
- Targeted replacement increased discovery versus random replacement in 3 of 12 settings.
From the original article
1 min read at arxiv.orgWhen a card number is compromised, an attacker may search for active numbers sharing its prefix. An issuer might respond by reissuing cards from heavily populated prefixes into less populated ones. We show that this intuitive count control can backfire.
By Wasif Faisal · arxiv.org
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