RODRIGUES, M. V. C.; http://lattes.cnpq.br/6373287656020353; RODRIGUES, Marcus Vinicius Corrêa.
Abstract:
This thesis deals with cryptographic keys based on biometrics. We propose a new technique
named Biometrics-Based Secret Key Agreement by Public Discussion with RFID systems
(BSKAPD-RFID). Three safety factors are used, represented by an iris code, an RFID tag and
a password.
An information reconciliation (IR) protocol that does not require the traditional advantage
distillation and privacy amplification phases is proposed. The IR protocol performed by
the RFID reader and tag enables a symmetric key agreement by discarding all the mismatching
bits present in genuine samples, while it can not do it by impostors, who are therefore rejected.
The BSKAPD system, besides adding revocability to generated keys, allows crypto-bio
key agreement between devices through wireless communication. These agreed keys have high
entropy, when compared with those obtained by others crypto-biometric systems, as crypto-bio
key regeneration systems. Another important safety feature is the renewal of the symmetric key
every positive authentication process.
Analytic expressions for IR protocol were derived and validated. The system was evaluated
on the public database ICE2005 and obtained a 270 binary digit cryptographic key with
estimated entropy of about 156 bits at False Acceptance Rate (FAR) of 0.00 % and at False
Rejection Rate (FRR) of 3.68 %.
Finally, an improvement of the algorithm for the Daugman’s iris recognition method is
introduced. It was designed for applications that have restrictions on the use of occlusion mask,
as occurs in the BSKAPD system. The distribution of the application points, after application
of the mentioned algorithm, is such that avoid regions with high rate of occlusions by eyelids
and eyelashes, therefore, reducing the impact of not using the occlusion mask in the matching
step.
