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42 lines
2.2 KiB
42 lines
2.2 KiB
\chapter{Conclusion and Outlook}
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\label{cha:conclusion}
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\section{Testing}
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These are the test results
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\section{Limitations}
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\begin{itemize}
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\item Documentation available for TPM APIs, but no changelog for \texttt{tpm2-tools}.
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\item Trusted boot and IMA can just handle static resources like files, kernel modules and firmware of hardware components.
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Code transmitted over network or otherwse dynamically generated can not be recognized.
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This is an open door for non-persistent attacks.
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\item Documentation on IMA is mostly outdated and so are some tools.
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Further customization of rules may be useful to reduce log size.
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However major Linux distributions support IMA by default on recent releases.
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\item Complexity of verifying system state is too high and is connected to system complexity.
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Reducing number of dependencies and relevant file count is key for this problem.
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\item Implemented DAA does not support a full dynamic group scheme.
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This might be useful in the future, maybe with a custom implementation of a recent DAA version.
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\end{itemize}
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\section{Future Work}
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\begin{itemize}
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\item Remove building tools on target device - just deliver binaries
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\item Remove complex runtime environments like Java, Python, etc. to reduce bloating the integrity logs
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\item Set file system read only, just use e.g. a ramdisk for working files
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\item Integrate USB sensors into the trusted/integrity environment, including device firmware.
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\end{itemize}
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\subsection{Closing the chain of trust between TPM manufacturer and DAA issuer}
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Activate a credential with to certify that the Membership key is in the Endorsement hierarchy, which can be verified with the TPM certificate.
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\begin{itemize}
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\item Theoretical concept in the \emph{Practical Guide to TPM 2.0, pp 109 ff}
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\item Practical approach: with EK, AK and AIK to show validity of EK:\\ \url{https://ericchiang.github.io/post/tpm-keys/?utm_campaign=Go%20Full-Stack&utm_medium=email&utm_source=Revue%20newsletter#credential-activation}
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\end{itemize}
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Further integration in the Digidow environment if DAA is useful for that.
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\section{Outlook}
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Hardening of the system beyond IMA useful.
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Minimization also useful, because the logging gets shorter.
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