Reconstructing AES Key Schedule Images with SAT and MaxSAT

Xiaojuan LIAO; Hui ZHANG; Miyuki KOSHIMURA

doi:10.1587/transinf.2015EDP7223

Reconstructing AES Key Schedule Images with SAT and MaxSAT

Xiaojuan LIAO, Hui ZHANG, Miyuki KOSHIMURA

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Cold boot attack is a side channel attack that recovers data from memory, which persists for a short period after power is lost. In the course of this attack, the memory gradually degrades over time and only a corrupted version of the data may be available to the attacker. Recently, great efforts have been made to reconstruct the original data from a corrupted version of AES key schedules, based on the assumption that all bits in the charged states tend to decay to the ground states while no bit in the ground state ever inverts. However, in practice, there is a small number of bits flipping in the opposite direction, called reverse flipping errors. In this paper, motivated by the latest work that formulates the relations of AES key bits as a Boolean Satisfiability problem, we move one step further by taking the reverse flipping errors into consideration and employing off-the-shelf SAT and MaxSAT solvers to accomplish the recovery of AES-128 key schedules from decayed memory images. Experimental results show that, in the presence of reverse flipping errors, the MaxSAT approach enables reliable recovery of key schedules with significantly less time, compared with the SAT approach that relies on brute force search to find out the target errors. Moreover, in order to further enhance the efficiency of key recovery, we simplify the original problem by removing variables and formulas that have relatively weak relations to the whole key schedule. Experimental results demonstrate that the improved MaxSAT approach reduces the scale of the problem and recover AES key schedules more efficiently when the decay factor is relatively large.

Publication: IEICE TRANSACTIONS on Information Vol.E99-D No.1 pp.141-150

Publication Date: 2016/01/01

Publicized: 2015/10/06

Online ISSN: 1745-1361

DOI: 10.1587/transinf.2015EDP7223

Type of Manuscript: PAPER

Category: Fundamentals of Information Systems

Authors

Xiaojuan LIAO
  Southwest University of Science and Technology
Hui ZHANG
  Southwest University of Science and Technology
Miyuki KOSHIMURA
  Kyushu University

Keyword

cold boot attack, maximum satisfiability, advanced encryption standard, key recovery

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Xiaojuan LIAO, Hui ZHANG, Miyuki KOSHIMURA, "Reconstructing AES Key Schedule Images with SAT and MaxSAT" in IEICE TRANSACTIONS on Information, vol. E99-D, no. 1, pp. 141-150, January 2016, doi: 10.1587/transinf.2015EDP7223.
Abstract: Cold boot attack is a side channel attack that recovers data from memory, which persists for a short period after power is lost. In the course of this attack, the memory gradually degrades over time and only a corrupted version of the data may be available to the attacker. Recently, great efforts have been made to reconstruct the original data from a corrupted version of AES key schedules, based on the assumption that all bits in the charged states tend to decay to the ground states while no bit in the ground state ever inverts. However, in practice, there is a small number of bits flipping in the opposite direction, called reverse flipping errors. In this paper, motivated by the latest work that formulates the relations of AES key bits as a Boolean Satisfiability problem, we move one step further by taking the reverse flipping errors into consideration and employing off-the-shelf SAT and MaxSAT solvers to accomplish the recovery of AES-128 key schedules from decayed memory images. Experimental results show that, in the presence of reverse flipping errors, the MaxSAT approach enables reliable recovery of key schedules with significantly less time, compared with the SAT approach that relies on brute force search to find out the target errors. Moreover, in order to further enhance the efficiency of key recovery, we simplify the original problem by removing variables and formulas that have relatively weak relations to the whole key schedule. Experimental results demonstrate that the improved MaxSAT approach reduces the scale of the problem and recover AES key schedules more efficiently when the decay factor is relatively large.
URL: https://globals.ieice.org/en_transactions/information/10.1587/transinf.2015EDP7223/_p

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@ARTICLE{e99-d_1_141,
author={Xiaojuan LIAO, Hui ZHANG, Miyuki KOSHIMURA, },
journal={IEICE TRANSACTIONS on Information},
title={Reconstructing AES Key Schedule Images with SAT and MaxSAT},
year={2016},
volume={E99-D},
number={1},
pages={141-150},
abstract={Cold boot attack is a side channel attack that recovers data from memory, which persists for a short period after power is lost. In the course of this attack, the memory gradually degrades over time and only a corrupted version of the data may be available to the attacker. Recently, great efforts have been made to reconstruct the original data from a corrupted version of AES key schedules, based on the assumption that all bits in the charged states tend to decay to the ground states while no bit in the ground state ever inverts. However, in practice, there is a small number of bits flipping in the opposite direction, called reverse flipping errors. In this paper, motivated by the latest work that formulates the relations of AES key bits as a Boolean Satisfiability problem, we move one step further by taking the reverse flipping errors into consideration and employing off-the-shelf SAT and MaxSAT solvers to accomplish the recovery of AES-128 key schedules from decayed memory images. Experimental results show that, in the presence of reverse flipping errors, the MaxSAT approach enables reliable recovery of key schedules with significantly less time, compared with the SAT approach that relies on brute force search to find out the target errors. Moreover, in order to further enhance the efficiency of key recovery, we simplify the original problem by removing variables and formulas that have relatively weak relations to the whole key schedule. Experimental results demonstrate that the improved MaxSAT approach reduces the scale of the problem and recover AES key schedules more efficiently when the decay factor is relatively large.},
keywords={},
doi={10.1587/transinf.2015EDP7223},
ISSN={1745-1361},
month={January},}

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TY - JOUR
TI - Reconstructing AES Key Schedule Images with SAT and MaxSAT
T2 - IEICE TRANSACTIONS on Information
SP - 141
EP - 150
AU - Xiaojuan LIAO
AU - Hui ZHANG
AU - Miyuki KOSHIMURA
PY - 2016
DO - 10.1587/transinf.2015EDP7223
JO - IEICE TRANSACTIONS on Information
SN - 1745-1361
VL - E99-D
IS - 1
JA - IEICE TRANSACTIONS on Information
Y1 - January 2016
AB - Cold boot attack is a side channel attack that recovers data from memory, which persists for a short period after power is lost. In the course of this attack, the memory gradually degrades over time and only a corrupted version of the data may be available to the attacker. Recently, great efforts have been made to reconstruct the original data from a corrupted version of AES key schedules, based on the assumption that all bits in the charged states tend to decay to the ground states while no bit in the ground state ever inverts. However, in practice, there is a small number of bits flipping in the opposite direction, called reverse flipping errors. In this paper, motivated by the latest work that formulates the relations of AES key bits as a Boolean Satisfiability problem, we move one step further by taking the reverse flipping errors into consideration and employing off-the-shelf SAT and MaxSAT solvers to accomplish the recovery of AES-128 key schedules from decayed memory images. Experimental results show that, in the presence of reverse flipping errors, the MaxSAT approach enables reliable recovery of key schedules with significantly less time, compared with the SAT approach that relies on brute force search to find out the target errors. Moreover, in order to further enhance the efficiency of key recovery, we simplify the original problem by removing variables and formulas that have relatively weak relations to the whole key schedule. Experimental results demonstrate that the improved MaxSAT approach reduces the scale of the problem and recover AES key schedules more efficiently when the decay factor is relatively large.
ER -