叢集式無線感測網路之遠程證實協定研究

Remote Attestation for Cluster-based Wireless Sensor Networks

石家維(Chia-Wei Shih)

指導教授 ： 顏嵩銘

國立中央大學/資訊電機學院/資訊工程學系/碩士(2014年)

摘要

由於感測終端元件大多佈署於惡劣環境中且受限於低成本之製作，
使得感測元件易成為攻擊者之目標。
攻擊者可將惡意程式植入至感測終端元件中，進而達到控制該元件之目的。
遠程證實 (Remote Attestation) 方法既為一種透過遠程方
式使得驗證者能檢驗感測終端元件內部軟體完整性的機制。

可 信 賴 平 台 模 組 (Trusted Platform Module)
是 根 據 可 信 賴 計 算 組 織 (Trusted Computing Group)
建議之規範所實作之防竄改密碼硬體模組。
可信賴平台模組可內嵌在一個計算平台中，
藉以提供此平台之系統狀態、軟體完整性測量結果與各類密碼演算法。

在無線感測網路中，由於對感測終端元件之低成本製作
與大規模佈署要求，使得在每一元件內嵌一個可信賴平台模組為一個不合宜方法。
對此我們採用叢集式 (Cluster-based) 無線感測網路架構以提升感測網路之存活期與可靠性，同時避免大量增加整體感測網路之布建成本。
在此架構下，將感測範圍區域內許多感測終端元件形成數個叢集，
每個叢集中有一個計算資源較好且內嵌可信賴平台模組之元件作為叢集頭 (Cluster Head)。

Krauß 等人提出之遠程證實協定允許感測終端元件驗證叢集頭之軟體完整性。
在我們研究過程中，發現 Krauß 等人的遠程證實協定造成叢集頭嚴重的儲存負擔，因此我們首先改善 Krauß 等人的方法以降低儲存空間之需求。
而在叢集式無線感測網路中叢集頭容易成為攻擊者之目標，我們提出新的協定讓基地台 (Base Station) 能夠驗證叢集頭之完整性。

在叢集式架構下，叢集頭負責將感測終端元件在叢集範圍所收集到的資料傳送到遠處的基地台。
為了確保資料的正確性，叢集頭必須驗證感測終端元件之完整性，
然而因感測元件之低成本需求並不適合在每一元件內嵌可信賴平台模組。
為 此 ， 我 們 僅 要 求 感 測 終 端 元 件 內 擁 有 少 量 的 唯 讀 記 憶 體 (Read-Only Memory)，提出一個虛擬可信賴平台模組驗證協定，使得叢集頭能驗證感測終端元件的完整性。
此外，叢集頭亦可透過此協定與感測終端元件重新建立一把共享金鑰。

關鍵字

無線感測網路 ； 遠程證實

並列摘要

Sensor nodes are usually vulnerable to be compromised due to their unattended
deployment and the low costs requirement. Thus, an attacker can reprogram the
compromised sensor and control the node to act on his behalf. Remote attestation
is the activity of making a claim about the internal state of a platform by supplying
evidence to a remote verifier.
The Trusted Platform Module (TPM) is a tamper-proof hardware based on the
Trusted Computing specification. A TPM is added to the platform in order to enable
functions, such as platform integrity measurement, remote attestation and crypto-
graphic functionality. However, in the wireless sensor network, the low cost design
and large scale deployment make it infeasible to equip each resource-constrained
sensor node with a TPM. We explore the cluster-based sensor network architecture
to increase the network lifetime and reliability without significantly increasing the
cost. The sensor network is organized in clusters where a minority of nodes are
equipped with TPMs and act as the cluster heads.
In this thesis, we first improve Krauβ et al.’s attestation protocol to decrease
the storage overhead. Their protocol allows the sensor nodes to verify whether the
platform configuration of the cluster head is trustworthy. However, a node acts as
the cluster head may be valuable to attack and our new protocol enables the base
station to verify the integrity of the cluster head.
A cluster head is responsible for verifying the trustworthiness of the sensor nodes
within the cluster. The low cost requirement of the sensor node precludes using an
expensive hardware, so we propose a virtual TPM attestation protocol. Assuming
only a small amount of read-only memory in each sensor node and the cluster head
can verify the integrity of each underlying sensor node. Furthermore, the cluster
head can re-establish the secret key with the dominated sensor nodes.

並列關鍵字

Wireless sensor network ； Remote attestation

參考文獻

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Telecommunications, pp. 1-8, 2009.

[3] C. Castelluccia, A. Francillon, D. Perito, and C. Soriente, “On the Difficulty of Software-based Attestation of Embedded Devices,” Proc. of the 16th ACM

the Network and Distributed System Security Symposium (NDSS), 2012.

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