commit 6984c0bbf72e690a8c15f23340c575287a4803dd
parent 84d397b31f9888c10c5b28addf863f0da4c0eb19
Author: Christian Grothoff <christian@grothoff.org>
Date: Fri, 26 Mar 2021 14:38:17 +0100
add references
Diffstat:
3 files changed, 221 insertions(+), 49 deletions(-)
diff --git a/2021-offline/literature.bib b/2021-offline/literature.bib
@@ -1,3 +1,48 @@
+@article{cap,
+author = {Gilbert, Seth and Lynch, Nancy},
+title = {Brewer's Conjecture and the Feasibility of Consistent, Available, Partition-Tolerant Web Services},
+year = {2002},
+issue_date = {June 2002},
+publisher = {Association for Computing Machinery},
+address = {New York, NY, USA},
+volume = {33},
+number = {2},
+issn = {0163-5700},
+url = {https://doi.org/10.1145/564585.564601},
+doi = {10.1145/564585.564601},
+abstract = {When designing distributed web services, there are three properties that are commonly desired: consistency, availability, and partition tolerance. It is impossible to achieve all three. In this note, we prove this conjecture in the asynchronous network model, and then discuss solutions to this dilemma in the partially synchronous model.},
+journal = {SIGACT News},
+month = jun,
+pages = {51–59},
+numpages = {9}
+}
+
+@misc{christodorescu2020twotier,
+ title={Towards a Two-Tier Hierarchical Infrastructure: An Offline Payment System for Central Bank Digital Currencies},
+ author={Mihai Christodorescu and Wanyun Catherine Gu and Ranjit Kumaresan and Mohsen Minaei and Mustafa Ozdayi and Benjamin Price and Srinivasan Raghuraman and Muhammad Saad and Cuy Sheffield and Minghua Xu and Mahdi Zamani},
+ year={2020},
+ eprint={2012.08003},
+ archivePrefix={arXiv},
+ primaryClass={cs.CR}
+}
+
+@InProceedings{chaum1988offine,
+author="Chaum, David
+and Fiat, Amos
+and Naor, Moni",
+editor="Goldwasser, Shafi",
+title="Untraceable Electronic Cash",
+booktitle="Advances in Cryptology --- CRYPTO' 88",
+year="1990",
+publisher="Springer New York",
+address="New York, NY",
+pages="319--327",
+abstract="The use of credit cards today is an act of faith on the p a t of all concerned. Each party is vulnerable to fraud by the others, and the cardholder in particular has no protection against surveillance.",
+isbn="978-0-387-34799-8"
+}
+
+
+
@Article{calhoun2019puf,
AUTHOR = {Calhoun, Jeff and Minwalla, Cyrus and Helmich, Charles and Saqib, Fareena and Che, Wenjie and Plusquellic, Jim},
TITLE = {Physical Unclonable Function (PUF)-Based e-Cash Transaction Protocol (PUF-Cash)},
@@ -35,3 +80,144 @@
year={1988},
organization={Springer}
}
+
+@INPROCEEDINGS{samsung2017knox,
+ author={M. {Dorjmyagmar} and M. {Kim} and H. {Kim}},
+ booktitle={2017 19th International Conference on Advanced Communication Technology (ICACT)},
+ title={Security analysis of Samsung Knox},
+ year={2017},
+ volume={},
+ number={},
+ pages={550-553},
+ doi={10.23919/ICACT.2017.7890150}}
+
+@INPROCEEDINGS{arm2016alias,
+ author={R. {Guanciale} and H. {Nemati} and C. {Baumann} and M. {Dam}},
+ booktitle={2016 IEEE Symposium on Security and Privacy (SP)},
+ title={Cache Storage Channels: Alias-Driven Attacks and Verified Countermeasures},
+ year={2016},
+ volume={},
+ number={},
+ pages={38-55},
+ abstract={Caches pose a significant challenge to formal proofs of security
+ for code executing on application processors, as the cache
+ access pattern of security-critical services may leak secret
+ information. This paper reveals a novel attack vector,
+ exposing a low-noise cache storage channel that can be
+ exploited by adapting well-known timing channel analysis
+ techniques. The vector can also be used to attack various
+ types of security-critical software such as hypervisors and
+ application security monitors. The attack vector uses
+ virtual aliases with mismatched memory attributes and
+ self-modifying code to misconfigure the memory system,
+ allowing an attacker to place incoherent copies of the same
+ physical address into the caches and observe which addresses
+ are stored in different levels of cache. We design and
+ implement three different attacks using the new vector on
+ trusted services and report on the discovery of an 128-bit
+ key from an AES encryption service running in TrustZone on
+ Raspberry Pi 2. Moreover, we subvert the integrity
+ properties of an ARMv7 hypervisor that was formally verified
+ against a cache-less model. We evaluate well-known
+ countermeasures against the new attack vector and propose a
+ verification methodology that allows to formally prove the
+ effectiveness of defence mechanisms on the binary code of
+ the trusted software.},
+ keywords={Security;Cache storage;Timing;Monitoring;Program processors;Virtual machine monitors;side channels;hypervisor;cache storage channels;verification},
+ doi={10.1109/SP.2016.11},
+ ISSN={2375-1207},
+ month={May},}
+
+@inproceedings{arm2017boomerang,
+ title={BOOMERANG: Exploiting the Semantic Gap in Trusted Execution Environments.},
+ author={Machiry, Aravind and Gustafson, Eric and Spensky, Chad and Salls, Christopher and Stephens, Nick and Wang, Ruoyu and Bianchi, Antonio and Choe, Yung Ryn and Kruegel, Christopher and Vigna, Giovanni},
+ booktitle={NDSS},
+ year={2017}
+}
+@article{zhang2016truspy,
+ title={TruSpy: Cache Side-Channel Information Leakage from the Secure World on ARM Devices.},
+ author={Zhang, Ning and Sun, Kun and Shands, Deborah and Lou, Wenjing and Hou, Y Thomas},
+ journal={IACR Cryptol. ePrint Arch.},
+ volume={2016},
+ pages={980},
+ year={2016}
+}
+
+
+
+@Misc{sim2019,
+ author = {Security Research Labs},
+ title = {New SIM attacks de-mystified, protection tools now available },
+ howpublished = {\url{https://srlabs.de/bites/sim_attacks_demystified/}},
+ year = {2019},
+}
+
+@TechReport{intel2020sgx,
+ author = {Dan Goodin},
+ title = {Intel SGX is vulnerable to an unfixable flaw that can steal crypto keys and more},
+ institution = {ARS Technica},
+ year = {2020},
+}
+
+
+
+
+@InProceedings{amd2019,
+ author = {Mengyuan Li and Yinqian Zhang and Zhiqiang Lin and Yan Solihin},
+ title = {Exploiting Unprotected I/O Operations inAMD’s Secure Encrypted Virtualization},
+ booktitle = {USENIX Security Symposium},
+ year = {2019},
+}
+
+@Misc{sim2020,
+ author = {Peter Buttler},
+ title = {WIB Vulnerability: Sim-Card that Allows Hackers to Takeover Phones},
+ howpublished = {\url{https://readwrite.com/2020/01/06/wib-vulnerability-sim-card-that-allows-hackers-to-takeover-phones/}},
+ month = {January},
+ year = {2020},
+}
+
+@Misc{intel2020sgaxe,
+ author = {Ravie Lakshmanan},
+ title = {Intel CPUs Vulnerable to New 'SGAxe' and 'CrossTalk' Side-Channel Attacks},
+ howpublished = {\url{https://thehackernews.com/2020/06/intel-sgaxe-crosstalk-attacks.html}},
+ month = {June},
+ year = {2020},
+}
+
+@Misc{intel2006survey,
+ author = {Alexander Nilsson and Pegah Nikbakht Bideh and Joakim Brorsson},
+ title = {A Survey of Published Attacks on Intel SGX},
+ howpublished = {\url{https://arxiv.org/pdf/2006.13598v1.pdf}},
+ year = {2006},
+}
+
+@inproceedings{arm2017clkscrew,
+author = {Tang, Adrian and Sethumadhavan, Simha and Stolfo, Salvatore},
+title = {CLKSCREW: Exposing the Perils of Security-Oblivious Energy Management},
+year = {2017},
+isbn = {9781931971409},
+publisher = {USENIX Association},
+address = {USA},
+abstract = {The need for power- and energy-efficient computing has resulted in aggressive cooperative hardware-software energy management mechanisms on modern commodity devices. Most systems today, for example, allow software to control the frequency and voltage of the underlying hardware at a very fine granularity to extend battery life. Despite their benefits, these software-exposed energy management mechanisms pose grave security implications that have not been studied before.In this work, we present the CLKSCREW attack, a new class of fault attacks that exploit the security-obliviousness of energy management mechanisms to break security. A novel benefit for the attackers is that these fault attacks become more accessible since they can now be conducted without the need for physical access to the devices or fault injection equipment. We demonstrate CLKSCREW on commodity ARM/Android devices. We show that a malicious kernel driver (1) can extract secret cryptographic keys from Trustzone, and (2) can escalate its privileges by loading self-signed code into Trustzone. As the first work to show the security ramifications of energy management mechanisms, we urge the community to re-examine these security-oblivious designs.},
+booktitle = {Proceedings of the 26th USENIX Conference on Security Symposium},
+pages = {1057–1074},
+numpages = {18},
+location = {Vancouver, BC, Canada},
+series = {SEC'17}
+}
+
+@inproceedings{arm2016cache,
+author = {Lipp, Moritz and Gruss, Daniel and Spreitzer, Raphael and Maurice, Cl\'{e}mentine and Mangard, Stefan},
+title = {ARMageddon: Cache Attacks on Mobile Devices},
+year = {2016},
+isbn = {9781931971324},
+publisher = {USENIX Association},
+address = {USA},
+abstract = {In the last 10 years, cache attacks on Intel x86 CPUs have gained increasing attention among the scientific community and powerful techniques to exploit cache side channels have been developed. However, modern smartphones use one or more multi-core ARM CPUs that have a different cache organization and instruction set than Intel x86 CPUs. So far, no cross-core cache attacks have been demonstrated on non-rooted Android smartphones. In this work, we demonstrate how to solve key challenges to perform the most powerful cross-core cache attacks Prime+Probe, Flush+Reload, Evict+Reload, and Flush+Flush on non-rooted ARM-based devices without any privileges. Based on our techniques, we demonstrate covert channels that outperform state-of-the-art covert channels on Android by several orders of magnitude. Moreover, we present attacks to monitor tap and swipe events as well as keystrokes, and even derive the lengths of words entered on the touchscreen. Eventually, we are the first to attack cryptographic primitives implemented in Java. Our attacks work across CPUs and can even monitor cache activity in the ARM TrustZone from the normal world. The techniques we present can be used to attack hundreds of millions of Android devices.},
+booktitle = {Proceedings of the 25th USENIX Conference on Security Symposium},
+pages = {549–564},
+numpages = {16},
+location = {Austin, TX, USA},
+series = {SEC'16}
+}
+\ No newline at end of file
diff --git a/2021-offline/offline.tex b/2021-offline/offline.tex
@@ -25,7 +25,7 @@
% * Offline payments should be a fallback, not regular (migitate risks!)
% * Payments with anonymity should not be "second class" citizens
-\title{Why a Digital Euro should be Online-first and Bearer-based}
+\title{Why a Digital Euro should be \\ Online-first and Bearer-based}
\author{Christian Grothoff \and Florian Dold}
\date{\today}
\begin{document}
@@ -79,7 +79,7 @@ are desirable for distributed systems:
parts of the distributed system temporarily impossible.
\end{itemize}
-The well-known CAP theorem proves that it is impossible to design a
+The well-known CAP theorem~\cite{cap} proves that it is impossible to design a
network protocol that simultaneously achieves all three properties.
For electronic payment systems, this means it is impossible to
simultaeneously protect against double-spending (Consistency) while
@@ -91,13 +91,15 @@ choices:
\item Protect against double-spending by taking away
control over computing from the user, typically using
hardware security elements that prevent the user from
- accessing certain functions of the device.
+ accessing certain functions of the device.\footnote{
+ A good example for such a design is~\cite{christodorescu2020twotier}.}
\item
% FIXME: this is a bit too technical
Retroactively identifying the user after network
connectivity is restored, in privay-preserving systems
using conditional deanonymization, and attempting to recoup
- the losses from the double-spending party afterwards.
+ the losses from the double-spending party afterwards.\footnote{
+ A classical example for such a design is~\cite{chaum1988offine}.}
\end{itemize}
There is no third choice. While there are minor variations how one
@@ -110,10 +112,24 @@ exhaustive.
If breaking the restrictive computing element's security properties
gives users the ability to access virtually unlimited funds, they
will. Hardware protections typically fall against well-equipped
-adversaries with plenty of time and expertise. Nation-state attackers
-and organized crime may even find it advantageous to force large-scale
-network outages to bring the payment system into a stage where they
-can multi-spend.
+adversaries with plenty of time and expertise.\footnote{Examples of vulnerabilities in such
+ hardware security systems include~\cite{samsung2017knox,arm2016alias,arm2016cache,arm2017boomerang,arm2017clkscrew,zhang2016truspy,intel2020sgx,intel2006survey,intel2020sgaxe,sim2019,sim2020,amd2019}, affecting all major hardware security architectures (Intel, Samsung, ARM, AMD, and SIM cards).} When Google published
+an attack on ARMs TrustZone, a key observation of the report (that is not uncommon
+for these types attacks) is:
+\begin{quote}
+ ``Unfortunately, the design issue outlined in this blog post is difficult to
+ address, and at times cannot be fixed without introducing additional
+ dedicated hardware or performing operations that risk rendering devices
+ unusable.''
+ -- \url{https://googleprojectzero.blogspot.com/2017/07/trust-issues-exploiting-trustzone-tees.html}
+\end{quote}
+So hardware security is hardly in a better shape than software security,
+and issues can be significantly more expensive to fix.
+
+Given a known vulnerability in an offline payment system, nation-state
+attackers and organized crime may even find it advantageous to force
+large-scale network outages to bring the payment system into a stage where
+they can multi-spend.
Deanonymization is similarly problematic, as the identified individual
may actually be the victim of a computer crime. Furthermore, even if
@@ -129,12 +145,12 @@ informational self-determination. Forcing users to use hardware that
they do not control is limiting their ability to control and customize
their digital lives.
-In privacy-friendly systems (like those based on Chaum) where citizens
-can use digital cash to make purchases anonymously, adding the ability
-to retroactively deanonymize double-spending users implies that
-accidentally double-spending (say after restoring from backup) voids
-the privacy assurances of the system. A key security property of the
-systems would thus be weakened and becomes brittle.
+In privacy-friendly systems (like those based on
+Chaum~\cite{chaum1988untraceable}) where citizens can use digital cash to
+make purchases anonymously, adding the ability to retroactively deanonymize
+double-spending users implies that accidentally double-spending (say after
+restoring from backup) voids the privacy assurances of the system. A key
+security property of the systems would thus be weakened and becomes brittle.
\subsection{Hurting availability}
diff --git a/presentations/bank/bank.tex b/presentations/bank/bank.tex
@@ -731,52 +731,21 @@ Once everyone is happy with Beta, move to production.
\end{frame}
-\begin{frame}[fragile]{Debian Installation Overview (1/3)}
-Recommended {\tt /etc/apt/preferences}:
-
-{\tiny
-\begin{verbatim}
-Package: *
-Pin: release a=stable
-Pin-Priority: 700
-
-Package: *
-Pin: release a=testing
-Pin-Priority: 650
-
-Package: *
-Pin: release a=unstable
-Pin-Priority: 600
-
-Package: *
-Pin: release l=Debian-Security
-Pin-Priority: 1000
-\end{verbatim}
-}
-\end{frame}
-
-\begin{frame}[fragile]{Debian Installation Overview (2/3)}
+\begin{frame}[fragile]{Ubuntu 20.04 LTS Installation Overview}
\noindent
-Recommended {\tt /etc/apt/sources.list}:
+Extend your {\tt /etc/apt/sources.list} with:
{\tiny
\begin{verbatim}
-deb http://ftp.ch.debian.org/debian/ buster main
-deb http://security.debian.org/debian-security buster/updates main
-deb http://ftp.ch.debian.org/debian/ testing main
-deb http://ftp.ch.debian.org/debian/ unstable main
-deb https://deb.taler.net/apt/debian sid main
+deb https://deb.taler.net/apt/ubuntu focal-fossa main
\end{verbatim}
}
-\end{frame}
-
-\begin{frame}[fragile]{Debian Installation Overview (3/3)}
\noindent
Key import and installation:
{\tiny
\begin{verbatim}
-# wget -O - https://taler.net/static/taler-systems.gpg.key | apt-key add -
+# wget -O - https://taler.net/static/taler-systems.gpg.key | apt-sign add -
# apt update
# apt install taler-exchange
\end{verbatim}
