Cryptography Reference
In-Depth Information
Figure 5.2. TinySec-Auth Packet Format in Bytes
incorporate a link-layer cryptographic mechanism without any hardware support, it
does not address the key-distribution problem (Chapter 6).
5.2.3 Lightweight Public Key Infrastructure for WSN
Although the applicability of Public Key Infrastructure (PKI)-based approaches
(Section 4.2) has been deemed inappropriate for a resource constraint environment
such as WSN, security researchers have been proposing new lightweight PKI-based
approaches for WSN. For instance, a simplified version of Secure Socket Layer (SSL)
has been proposed in WSN (Wander et al. 2005). Although this SSL version has a
lesser overhead when compared to the usual SSL/TLS protocol, it is still not directly
applicable to mobile sensor nodes because it would lead to increased communication
and computational overhead. For instance, in an ad-hoc mobile sensor network, the
nodes keep changing their location, and any change in their position would compel
them to initiate the SSL protocol before informing their neighbors of their new loca-
tion. In addition, schemes such as TinyPK have been designed that are in conjunction
with TinySec and facilitate authentication and key agreement between sensor nodes
(Watro et al. 2004). However, TinyPK implements Diffie-Hellman key exchange pro-
tocol that is susceptible to a man-in-the-middle attack. Huang et al. (2003) proposed
a hybrid architecture for authenticated key establishment of a session key between a
leaf node and a sink node or an end user. This protocol leverages on the difference
in the computational and communication capabilities between the leaf node and the
resource abundant device (sink node or end user). During the inception of the proto-
col, both parties exchange certificates issued by a Certificate Authority (CA) to extract
each other's public keys. However, the corresponding private keys are discovered after
both parties run the protocol. This step in this protocol can easily be exploited by an
adversary by replaying a valid certificate that would result in a DoS attack. As a result,
the nodes are forced to perform expensive computations and waste their resources and
bandwidth. In addition, Tian et al. (2005) showed a serious vulnerability in Huang et
al.'s scheme wherein an end user can easily discover the long-term private key of a leaf
node after having one normal run of the protocol.
To expunge the transmission of public key certificates, Ren et al. (2012) propose a
Hybrid Authentication Scheme (HAS) for a multiuser broadcast authentication scheme
in WSN. In this scheme, each sensor node is preloaded with the required public key
information of the end user using the Bloom filter and Merkle hash tree (Merkle 1980;
Mitzenmacher 2002). However, HAS with the Merkle hash tree does not facilitate user
scalability, i.e., a new user can only be added into the network after revocation of the
old user.
Search WWH ::




Custom Search