Anonymity in Wireless Networks
Under Traffic Analysis Attacks
Hugo Moreira de Sousa Pinto
Professor Daniel Lucani
Professor João Barros
© 2005, it - instituto de telecomunicações. Todos os direitos reservados.
Security in Communications
 Measures to deter violations that involve the transmission of information
 Authentication
 Access Control
 Data Confidentiality
 Data Integrity
 Non Repudiation
 Anonymity – hiding the parties involved in a communication
 Wireless Networks
 Session anonymity
 Scheduling mechanisms
 Dummy transmissions
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Problem Setup
A1
A2
A3
Wireless Line network
Possible sessions
A1 <-> A2
 Types of sessions
Unicast Sessions:
e.g. VoIP conversation
A2 <-> A3
A1 <-> A3
A1
A2
A1 -> {A2 , A3}
A2 -> {A1 , A3}
A1 <-> A2
A3 -> {A1 , A2}
Multicast Sessions:
e.g. Sharing a picture
A1
A2
A1 -> {A2,A3}
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A3
Scheduling – 3 node line network
 Pattern 1
Possible sessions
A1 <-> A2
A2 <-> A3
A1 <-> A3
A1
A1 -> {A2 , A3}
A3}
A2
A2 -> {A1 , A3}
A3}
t1
t2
t3
t4
x
x
x
x
A1
A2
A3
Not Anonymous
 Pattern 2
A3
A3 -> {A1 , A2}
A2}
t1
A1
t2
t3
x
A2
x
A3
x
x
Anonymous
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t4
Design Objectives
 Provide session anonymity
 Scalable to longer networks
 Maximize throughput
 Minimize energy
 Possibility of simultaneous transmissions
t1
A1
t2 t3 t4 t5 t6
X
A2
X
A3
X
X
X
A1
A4
A5
X
A2
A3
X
X
A6
X
X
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A4
A5
A6
Cost of anonymity
𝐶𝑜𝑠𝑡 𝑜𝑓 𝑎𝑛𝑜𝑛𝑦𝑚𝑖𝑡𝑦 𝑆𝑖 =
𝐶𝑜𝑠𝑡 𝑜𝑓 𝑆𝑖 𝑤𝑖𝑡ℎ 𝑎𝑛𝑜𝑛𝑦𝑚𝑖𝑡𝑦
𝐶𝑜𝑠𝑡 𝑜𝑓 𝑆𝑖 𝑤𝑖𝑡ℎ𝑜𝑢𝑡 𝑎𝑛𝑜𝑛𝑦𝑚𝑖𝑡𝑦
K=3
 Unicast sessions: 𝐴𝑖
𝐴𝑖+𝑘
A1
4
3
2
1
0
A2
A3
A4
A5
Energy
0
5
10
K->
 For k>=5 we have free anonymity
in terms of throughput
Cost
Cost
Throughput
50
40
30
20
10
0
N = 20
N = 30
N = 40
N = 50
0
10
K ->
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Conclusions and future work
 Session anonymity
 No cost in throughput
 High cost in energy if the network size is too long
 Use of transmission mechanisms such as network coding
 Double throughput
 Reduce energy consumption by half
 Study trade-offs between anonymity and cost
 Look into different network topologies
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