Employing PKI to Secure Smart Grid

Employing PKI to Secure Smart Grid Communication
In this subsection, we argue that PKI is a potential mechanism
for securing smart grid communication as it can meet most
security requirements of smart grid communication networks.
As shown in Fig. 2, security requirements of entity authen-
tication and non-repudiation can be satisfied by employing
digital signatures. A PKI binds the public keys and the entities’
identities through the use of digital certificates. The binding
is established through a registration process, and after a
trust
authority (TA) (consisting of the registration authority,
certificate
authority and validation authority) assures the correctness
of the binding, the TA issues the certificate to the
entity.
Since the public key of each entity is made available to
all
other entities in the network, entity authentication can be
achieved.
The simplest form of a certificate consists of the following
contents: Cert
j
= {id
j
, PK
,
{SIG
SK
TA
{h(id
j
|| PK
j
|| ExpT)}}, where id
denotes entity j’s
identity, PK
j
j
represents the public key of entity j , ExpT
denotes certificate expiry time, SK
denotes the private key
of TA and SIG
SK
TA
{h(id
j
|| PK
j
TA
|| ExpT)} is a signature over
h(id
j
|| PK
j
|| ExpT) based on SK
. Here, h(.) indicates hash
function operation. Thus, any entity can sign any outgoing
TA
j
, Exp
T
message using its unique private key. An outgoing
message is then transmitted as {M,
SIG
SK
j
{h(id
j
|| M)}, Cert
}, where M denotes
the outgoing message and SK
j
denotes the private
key of entity j.
Of course, timestamps
should
be included in Mto
prevent the replay
attack.
When it is received, the receiver verifies
the signature of the sender using its public
key. Upon successful verification, the
identity
of the sender is confirmed and it can
also
be concluded that the message content
has
not been altered. In other words, entity
authentication
and non-repudiation are
achieved.
In addition, conditional privacy can
be
preserved using anonymous certificates, as
they
do not contain the identity information
of
their holders. In this case, when necessary,
the
identity of the holder of an anonymous
certificate
can only be revealed by a TA.