917 research outputs found
MemShield: GPU-assisted software memory encryption
Cryptographic algorithm implementations are vulnerable to Cold Boot attacks,
which consist in exploiting the persistence of RAM cells across reboots or
power down cycles to read the memory contents and recover precious sensitive
data. The principal defensive weapon against Cold Boot attacks is memory
encryption. In this work we propose MemShield, a memory encryption framework
for user space applications that exploits a GPU to safely store the master key
and perform the encryption/decryption operations. We developed a prototype that
is completely transparent to existing applications and does not require changes
to the OS kernel. We discuss the design, the related works, the implementation,
the security analysis, and the performances of MemShield.Comment: 14 pages, 2 figures. In proceedings of the 18th International
Conference on Applied Cryptography and Network Security, ACNS 2020, October
19-22 2020, Rome, Ital
ret2spec: Speculative Execution Using Return Stack Buffers
Speculative execution is an optimization technique that has been part of CPUs
for over a decade. It predicts the outcome and target of branch instructions to
avoid stalling the execution pipeline. However, until recently, the security
implications of speculative code execution have not been studied.
In this paper, we investigate a special type of branch predictor that is
responsible for predicting return addresses. To the best of our knowledge, we
are the first to study return address predictors and their consequences for the
security of modern software. In our work, we show how return stack buffers
(RSBs), the core unit of return address predictors, can be used to trigger
misspeculations. Based on this knowledge, we propose two new attack variants
using RSBs that give attackers similar capabilities as the documented Spectre
attacks. We show how local attackers can gain arbitrary speculative code
execution across processes, e.g., to leak passwords another user enters on a
shared system. Our evaluation showed that the recent Spectre countermeasures
deployed in operating systems can also cover such RSB-based cross-process
attacks. Yet we then demonstrate that attackers can trigger misspeculation in
JIT environments in order to leak arbitrary memory content of browser
processes. Reading outside the sandboxed memory region with JIT-compiled code
is still possible with 80\% accuracy on average.Comment: Updating to the cam-ready version and adding reference to the
original pape
KCRS: A Blockchain-Based Key Compromise Resilient Signature System
Digital signatures are widely used to assure authenticity and integrity of messages (including blockchain transactions). This assurance is based on assumption that the private signing key is kept secret, which may be exposed or compromised without being detected in the real world. Many schemes have been proposed to mitigate this problem, but most schemes are not compatible with widely used digital signature standards and do not help detect private key exposures. In this paper, we propose a Key Compromise Resilient Signature (KCRS) system, which leverages blockchain to detect key compromises and mitigate the consequences. Our solution keeps a log of valid certificates and digital signatures that have been issued on the blockchain, which can deter the abuse of compromised private keys. Since the blockchain is an open system, KCRS also provides a privacy protection mechanism to prevent the public from learning the relationship between signatures. We present a theoretical framework for the security of the system and a provably-secure construction. We also implement a prototype of KCRS and conduct experiments to demonstrate its practicability
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