Structural Properties of Cryptographic Sequences - Computational Intelligence in Security for Information Systems - page 169

a reader, by means of radio waves [2]. The simplest form of RFID consists of a tag
(containing a minute integrated circuit with its corresponding antenna) and a RFID
reader, although in most cases this basic system is also connected to an information
system (back-end) with a database that stores all the information relating to the object.
Here, this technology can show its full potential, but it is also the most vulnerable
point from the security aspect.
Traceability is defined, according to the International Standards Organization
(ISO) [3], as “The property of the result of a measurement or the value of a standard
whereby it can be related to stated references, usually national or international stan-
dards, through an unbroken chain of comparisons all having stated uncertainties”.
Traceability systems based on RFID technology are increasingly common and they
provide many advantages over other systems (bar codes, for example). In [4] a RFID-
based traceability system was proposed that, in addition to traceability, facilitates
control of the requirements at every stage the product must pass through and the lo-
cating of the entity responsible for certification at every checkpoint. This involved the
use of aggregate signatures, defined in [5] as “a function in which given a set of U
users, each one with a public and private key (K u+ and K u- ), and a subset V ⊆ U, if

each user u V produces a signature σ u of a message M u these signatures can be

compacted into an aggregated signature σ by an untrusted third party different from
the users of V”.
The use of aggregate signatures allows the validity of the data held in a tag to be
verified in one cryptographic operation. This takes place at every checkpoint before
new data is introduced and the new aggregate signature is updated. If everything is
correct, the corresponding computations are done and the data recorded in both the
RFID label and the information system.

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Fig. 1. Checkpoint Architecture