Cryptography Reference
In-Depth Information
Alice
n 1 , n 2 , n 3 . . . , n d
I
id A , k A
II
E
[ idx 1 ] ,
E
[ idx 2 ], …….
E
[ idx pd ]
id
id
id
A
A
A
E
[ k 1 ],
E
[ k 2 ], ……..
E
[ k (1-p)d ]
id
id
id
A
A
A
III
E
[ id 1 ||k 1 ]
E
[ id 2 ,||k 2 ], …. ,
E
[ id (1-p) d||k (1-p)d ]
id
N
id
id
N
N
E
[id 1 ||idx 1 ||K PK ,....., id (1-p)pd ,||idx (1-p)pd , ||K pK ] 1
IV
id
A
E
[id 1 ||idx 1 ||K PK ,....., id (1-p)pd ,||id x(1-p)pd , ||K pK ] pd
id
A
V
E
[idx 1 ||K 1 , idx2,||k2, ….,idx i ||K i ] where i(1-p)d
N
k A = Alice's key ring
idx i is the matching index number in the key ring
K PK = Path key
ID N = identity of immediate neighbor
Figure 8.6. Message Exchange for the Basic Scheme
Phase IV . In Phase IV , each of the pd secure neighbors compare their key indexes with
the list provided by Alice to find a common path key. Each discovered path key ( K PK ) is
sent to Alice by encrypting it with the link key. As a result, there could be multiple path
keys K PK for the distant neighbor ni.
Phase V . In Phase V , upon receiving the path key, Alice selects only one of them ( K i ), and
the path key is sent to the corresponding neighbor with its key index number idx i , where
i ≤ (1- p ) d ). After this phase, if there are neighbors that still cannot establish a path key
then Alice starts a new path key discovery iteration starting from Phase III . New iteration
also includes the last added neighbors in the previous path key discovery as the shared
key members. This loop terminates when there is no new neighbor added after the last
path key discovery process.
In this scheme, the links to be secured are defined by the clustering protocol dis-
cussed in Section 8.4.1. Securing all the physical neighbors for each sensor node would
give the highest network configuration performance. However, the communication and
computation costs are higher in this case. Therefore, only the required neighbors that are
in a floating state can be selected for establishing secure links while extending the clus-
ters. This reduction can improve the communication costs and hence the computation
 
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