![](bg4.png)
and does not rest on computational intractability as-
sumptions beyond what is needed to establish se-
cure symmetrically encrypted channels. Even from
an information-theoretic point of view, it is possible
to use our scheme for secret key-exchange only, so
as to gain security even against a computationally un-
bounded adversary. Moreover, our scheme is light-
weight in the sense of imposing little computational
effort within each relay node. So it can be imple-
mented in cheap and power-limited devices, partic-
ularly small sensor-devices. The protocol offers two
degrees of freedom which lets us control the commu-
nication overhead and find a suitable balance between
security and communication overhead. This facili-
tates a fair-use policy of the channel, if multiple ses-
sions run concurrently over the same set of devices.
In future work, we will report on empirical evaluation
via simulation.
Unfortunately, our protocol is vulnerable to
denial-of-service attacks in its present form. The
XOR-sharing as we used is most vulnerable to cor-
rupted shares, since the secret is unrecoverable if one
share is lost or modified. However, XOR-sharing is
not a must and might be replaced by conventional
polynomial sharing that comes with better error cor-
recting facilities (e.g. Shamir’s scheme). Guarding
against loss of shares and routing attacks are subject
of future research.
This work is written with wireless networks in
mind, but the presented algorithm can work in any
network where the construction of the aforemen-
tioned layered architecture is possible. In particular,
it seems possible to apply it in wired networks like
cascades of mix servers presented in (Klonowski and
Kutylowski, 2005).
ACKNOWLEDGEMENTS
The paper was partially supported by grant S10026
from the Institute of Mathematics and Computer Sci-
ence of the Wroclaw University of Technology.
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