Cold boot attacks inspect the corrupted random access memory soon after the
power has been shut down. While most of the bits have been corrupted, many
bits, at random locations, have not. Since the keys in many encryption schemes
are being expanded in memory into longer keys with fixed redundancies, the keys
can often be restored. In this work, we combine a novel cryptographic variant
of a deep error correcting code technique with a modified SAT solver scheme to
apply the attack on AES keys. Even though AES consists of Rijndael S-box
elements, that are specifically designed to be resistant to linear and
differential cryptanalysis, our method provides a novel formalization of the
AES key scheduling as a computational graph, which is implemented by a neural
message passing network. Our results show that our methods outperform the state
of the art attack methods by a very large margin.

本文主要介绍了一种新型密码学变体，使用修改过的 SAT 求解器方案，结合深度纠错码技术攻击 AES 密钥，并将 AES 密钥调度形式化为计算图，实现神经消息传递网络。实验表明，此方法的表现比现有攻击方法要好得多。

使用深度冷启动攻击恢复 AES 密钥

Recovering AES Keys with a Deep Cold Boot Attack

Given two random variables $X$ and $Y$, an operational approach is undertaken
to quantify the ``leakage'' of information from $X$ to $Y$. The resulting
measure $\mathcal{L}(X \!\! \to \!\! Y)$ is called \emph{maximal leakage}, and
is defined as the multiplicative increase, upon observing $Y$, of the
probability of correctly guessing a randomized function of $X$, maximized over
all such randomized functions. A closed-form expression for $\mathcal{L}(X \!\!
\to \!\! Y)$ is given for discrete $X$ and $Y$, and it is subsequently
generalized to handle a large class of random variables. The resulting
properties are shown to be consistent with an axiomatic view of a leakage
measure, and the definition is shown to be robust to variations in the setup.
Moreover, a variant of the Shannon cipher system is studied, in which
performance of an encryption scheme is measured using maximal leakage. A
single-letter characterization of the optimal limit of (normalized) maximal
leakage is derived and asymptotically-optimal encryption schemes are
demonstrated. Furthermore, the sample complexity of estimating maximal leakage
from data is characterized up to subpolynomial factors. Finally, the
\emph{guessing} framework used to define maximal leakage is used to give
operational interpretations of commonly used leakage measures, such as Shannon
capacity, maximal correlation, and local differential privacy.

本文旨在量化信息的流失，从而定义最大泄漏等概念，研究了采用最大泄漏方式的密码方案，并推导了最佳限制以及样本复杂度。同时，使用存在猜测的框架为香农容量，最高相关性和局部差分隐私等常用泄漏度量提供了操作性的解释。

信息泄漏的操作方法

An Operational Approach to Information Leakage

Recently two encryption schemes were proposed by combining circular bit shift
and XOR operations, under the control of a pseudorandom bit sequence (PRBS)
generated from a chaotic system. This paper studies the security of these two
encryption schemes and reports the following findings: 1) there exist some
security defects in both schemes; 2) the underlying chaotic PRBS can be
reconstructed as an equivalent key by using only two chosen plaintexts; 3) most
elements in the underlying chaotic PRBS can be obtained by a differential
known-plaintext attack using only two known plaintexts. Experimental results
are given to demonstrate the feasibility of the proposed attack.

研究了两种结合了循环位移和异或操作的加密方案的安全性，并发现存在一些安全缺陷，底层混沌 PRBS 可以通过两个已知明文攻击进行重建并获得大多数元素。