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< title > Review of Petzi et al. 2022< / title >
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< b > SCRAPS< / b > :< br > < b > S< / b > calable < b > C< / b > ollective < b > R< / b > emote < b > A< / b > ttestation for < b > P< / b > ub-< b > S< / b > ub IoT Networks with Untrusted Proxy Verifier
< br > < br >
< small > < i > Petzi et al.< / i > 2022 (31st USENIX Security Symposium, pp. 3484-3501)< / small >
< br > < small > Summary: Garrett Mills < glm@ku.edu> < br >
< i style = "color: #888" > https://garrettmills.dev/go/scraps< / i > < / small >
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< section >
< b > Attestation< / b > < i > (noun)< / i > - the activity of making a claim to an appraiser about the properties of a target by supplying evidence which
supports that claim. < small > < i > [1]< / i > < / small >
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< section >
< b > Smart Contracts< / b > < i > (noun)< / i > - scripts stored on the blockchain. The contracts have their own state, and are triggered by messages/transactions
sent to their respective addresses. < small > < i > [2]< / i > < / small >
< / section >
< section >
< b > Challenges adapting RA to IoT:< / b > < br > < br >
< ol >
< li > IoT relies on asynchronous channels< / li >
< li > IoT devices may go offline to save power< / li >
< li > IoT networks use untrusted brokers< / li >
< / ol >
< / section >
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< b > SCRAPS< / b > < br > < br >
< ul >
< li > Manufacturer's SC (config)< / li >
< li > ProxyVerifier SC (appraiser)< / li >
< li > Prover (target)< / li >
< li > Verifier (requester)< / li >
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< li > < b > Prover registers with Broker< / b > < / li >
< li > Prover computes measurement using chain hash< / li >
< li > ProxyVerifier appraises evidence using config & freshness< / li >
< li > Verifier requests appraisal from ProxyVerifier< / li >
< / ol >
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< li > Prover registers with Broker< / li >
< li > < b > Prover computes measurement using chain hash< / b > < / li >
< li > ProxyVerifier appraises evidence using config & freshness< / li >
< li > Verifier requests appraisal from ProxyVerifier< / li >
< / ol >
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< li > Prover registers with Broker< / li >
< li > Prover computes measurement using chain hash< / li >
< li > < b > ProxyVerifier appraises evidence using config & freshness< / b > < / li >
< li > Verifier requests appraisal from ProxyVerifier< / li >
< / ol >
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< ol style = "font-size: 0.75em;" >
< li > Prover registers with Broker< / li >
< li > Prover computes measurement using chain hash< / li >
< li > ProxyVerifier appraises evidence using config & freshness< / li >
< li > < b > Verifier requests appraisal from ProxyVerifier< / b > < / li >
< / ol >
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< img src = "img/fig-6.png" alt = "Figure 6" style = "filter: invert(100%);" >
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< img src = "img/fig-8.png" alt = "Figure 8" style = "filter: invert(100%);" >
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< h3 > Smart Contracts< / h3 >
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< b > Stength:< / b > Problem/architecture formulation
< / section >
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< b > Strength:< / b > Performance
< / section >
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< b > Strength:< / b > Appraiser is as secure as the chain
< / section >
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< b > Strength:< / b > Use of blockchain eliminates some attacks
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< b > Weakness:< / b > Interaction between freshness and sleep
< / section >
< section style = "font-size: 0.9em" >
< b > Weakness:< / b > Limited appraisal & trust flexibility
< / section >
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< b > Weakness:< / b > Determination of $T_{min}$ and $T_{exp}$
< / section >
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< b > Weakness:< / b > Depends on manufacturer's pub-key to verify
< / section >
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< b > Weakness:< / b > Evidence & appraisal privacy
< / section >
< section style = "font-size: 0.9em" >
< b > Future work:< / b > Formal verification of ProxyVerifier
< / section >
< section style = "font-size: 0.9em" >
< b > Future work:< / b > SC-based flexible mechanisms
< / section >
< section style = "font-size: 0.9em" >
< b > Future work:< / b > SC-based flexible mechanisms < i > (reprise)< / i >
< / section >
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< b > References< / b >
< br >
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< p > [0] Petzi, Lukas, Ala Eddine Ben Yahya, Alexandra Dmitrienko, Gene Tsudik, Thomas Prantl, and Samuel Kounev. “SCRAPS: Scalable Collective Remote Attestation for Pub-Sub IoT Networks with Untrusted Proxy Verifier,” 2022, 18.< / p >
< p > [1] Coker, George, Joshua Guttman, Peter Loscocco, Amy Herzog, Jonathan Millen, Brian O’ – < / p >
< p > [2] Christidis, Konstantinos, and Michael Devetsikiotis. “Blockchains and Smart Contracts for the Internet of Things.” IEEE Access 4 (2016): 2292– < / p >
< p > [3] Helble, Sarah C., Ian D. Kretz, Peter A. Loscocco, John D. Ramsdell, Paul D. Rowe, and Perry Alexander. “Flexible Mechanisms for Remote Attestation.” ACM Transactions on Privacy and Security 24, no. 4 (September 30, 2021): 29:1-29:23. https://doi.org/10.1145/3470535.< / p >
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