---
_id: '377'
abstract:
- lang: eng
  text: In this paper, we study how AES key schedules can be reconstructed from decayed
    memory. This operation is a crucial and time consuming operation when trying to
    break encryption systems with cold-boot attacks. In software, the reconstruction
    of the AES master key can be performed using a recursive, branch-and-bound tree-search
    algorithm that exploits redundancies in the key schedule for constraining the
    search space. In this work, we investigate how this branch-and-bound algorithm
    can be accelerated with FPGAs. We translated the recursive search procedure to
    a state machine with an explicit stack for each recursion level and create optimized
    datapaths to accelerate in particular the processing of the most frequently accessed
    tree levels. We support two different decay models, of which especially the more
    realistic non-idealized asymmetric decay model causes very high runtimes in software.
    Our implementation on a Maxeler dataflow computing system outperforms a software
    implementation for this model by up to 27x, which makes cold-boot attacks against
    AES practical even for high error rates.
author:
- first_name: Heinrich
  full_name: Riebler, Heinrich
  id: '8961'
  last_name: Riebler
- first_name: Tobias
  full_name: Kenter, Tobias
  id: '3145'
  last_name: Kenter
- first_name: Christian
  full_name: Plessl, Christian
  id: '16153'
  last_name: Plessl
  orcid: 0000-0001-5728-9982
- first_name: Christoph
  full_name: Sorge, Christoph
  last_name: Sorge
citation:
  ama: 'Riebler H, Kenter T, Plessl C, Sorge C. Reconstructing AES Key Schedules from
    Decayed Memory with FPGAs. In: <i>Proceedings of Field-Programmable Custom Computing
    Machines (FCCM)</i>. IEEE; 2014:222-229. doi:<a href="https://doi.org/10.1109/FCCM.2014.67">10.1109/FCCM.2014.67</a>'
  apa: Riebler, H., Kenter, T., Plessl, C., &#38; Sorge, C. (2014). Reconstructing
    AES Key Schedules from Decayed Memory with FPGAs. <i>Proceedings of Field-Programmable
    Custom Computing Machines (FCCM)</i>, 222–229. <a href="https://doi.org/10.1109/FCCM.2014.67">https://doi.org/10.1109/FCCM.2014.67</a>
  bibtex: '@inproceedings{Riebler_Kenter_Plessl_Sorge_2014, title={Reconstructing
    AES Key Schedules from Decayed Memory with FPGAs}, DOI={<a href="https://doi.org/10.1109/FCCM.2014.67">10.1109/FCCM.2014.67</a>},
    booktitle={Proceedings of Field-Programmable Custom Computing Machines (FCCM)},
    publisher={IEEE}, author={Riebler, Heinrich and Kenter, Tobias and Plessl, Christian
    and Sorge, Christoph}, year={2014}, pages={222–229} }'
  chicago: Riebler, Heinrich, Tobias Kenter, Christian Plessl, and Christoph Sorge.
    “Reconstructing AES Key Schedules from Decayed Memory with FPGAs.” In <i>Proceedings
    of Field-Programmable Custom Computing Machines (FCCM)</i>, 222–29. IEEE, 2014.
    <a href="https://doi.org/10.1109/FCCM.2014.67">https://doi.org/10.1109/FCCM.2014.67</a>.
  ieee: 'H. Riebler, T. Kenter, C. Plessl, and C. Sorge, “Reconstructing AES Key Schedules
    from Decayed Memory with FPGAs,” in <i>Proceedings of Field-Programmable Custom
    Computing Machines (FCCM)</i>, 2014, pp. 222–229, doi: <a href="https://doi.org/10.1109/FCCM.2014.67">10.1109/FCCM.2014.67</a>.'
  mla: Riebler, Heinrich, et al. “Reconstructing AES Key Schedules from Decayed Memory
    with FPGAs.” <i>Proceedings of Field-Programmable Custom Computing Machines (FCCM)</i>,
    IEEE, 2014, pp. 222–29, doi:<a href="https://doi.org/10.1109/FCCM.2014.67">10.1109/FCCM.2014.67</a>.
  short: 'H. Riebler, T. Kenter, C. Plessl, C. Sorge, in: Proceedings of Field-Programmable
    Custom Computing Machines (FCCM), IEEE, 2014, pp. 222–229.'
date_created: 2017-10-17T12:42:05Z
date_updated: 2023-09-26T13:33:50Z
ddc:
- '040'
department:
- _id: '27'
- _id: '518'
- _id: '78'
doi: 10.1109/FCCM.2014.67
file:
- access_level: closed
  content_type: application/pdf
  creator: florida
  date_created: 2018-03-20T07:14:20Z
  date_updated: 2018-03-20T07:14:20Z
  file_id: '1397'
  file_name: 377-FCCM14.pdf
  file_size: 1003907
  relation: main_file
  success: 1
file_date_updated: 2018-03-20T07:14:20Z
has_accepted_license: '1'
keyword:
- coldboot
language:
- iso: eng
page: 222-229
project:
- _id: '1'
  grant_number: '160364472'
  name: SFB 901
- _id: '14'
  grant_number: '160364472'
  name: SFB 901 - Subprojekt C2
- _id: '4'
  name: SFB 901 - Project Area C
- _id: '34'
  grant_number: '610996'
  name: Self-Adaptive Virtualisation-Aware High-Performance/Low-Energy Heterogeneous
    System Architectures
publication: Proceedings of Field-Programmable Custom Computing Machines (FCCM)
publisher: IEEE
quality_controlled: '1'
status: public
title: Reconstructing AES Key Schedules from Decayed Memory with FPGAs
type: conference
user_id: '15278'
year: '2014'
...