Preimage Attacks on Feistel-SP Functions: Impact of Omitting the Last Network Twist

Yu SASAKI

doi:10.1587/transfun.E98.A.61

Preimage Attacks on Feistel-SP Functions: Impact of Omitting the Last Network Twist

Yu SASAKI

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In this paper, generic attacks are presented against hash functions that are constructed by a hashing mode instantiating a Feistel or generalized Feistel networks with an SP-round function. It is observed that the omission of the network twist in the last round can be a weakness against preimage attacks. The first target is a standard Feistel network with an SP round function. Up to 11 rounds can be attacked in generic if a condition on a key schedule function is satisfied. The second target is a 4-branch type-2 generalized Feistel network with an SP round function. Up to 15 rounds can be attacked in generic. These generic attacks are then applied to hashing modes of ISO standard ciphers Camellia-128 without FL and whitening layers and CLEFIA-128.

Publication: IEICE TRANSACTIONS on Fundamentals Vol.E98-A No.1 pp.61-71

Publication Date: 2015/01/01

Publicized

Online ISSN: 1745-1337

DOI: 10.1587/transfun.E98.A.61

Type of Manuscript: Special Section PAPER (Special Section on Cryptography and Information Security)

Category: Symmetric Key Based Cryptography

Authors

Yu SASAKI
NTT Corporation

Keyword

Feistel, generalized Feistel, SP round function, hashing modes, meet-in-the-middle attack, preimage attack, Camellia, CLEFIA

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Yu SASAKI, "Preimage Attacks on Feistel-SP Functions: Impact of Omitting the Last Network Twist" in IEICE TRANSACTIONS on Fundamentals, vol. E98-A, no. 1, pp. 61-71, January 2015, doi: 10.1587/transfun.E98.A.61.
Abstract: In this paper, generic attacks are presented against hash functions that are constructed by a hashing mode instantiating a Feistel or generalized Feistel networks with an SP-round function. It is observed that the omission of the network twist in the last round can be a weakness against preimage attacks. The first target is a standard Feistel network with an SP round function. Up to 11 rounds can be attacked in generic if a condition on a key schedule function is satisfied. The second target is a 4-branch type-2 generalized Feistel network with an SP round function. Up to 15 rounds can be attacked in generic. These generic attacks are then applied to hashing modes of ISO standard ciphers Camellia-128 without FL and whitening layers and CLEFIA-128.
URL: https://globals.ieice.org/en_transactions/fundamentals/10.1587/transfun.E98.A.61/_p

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@ARTICLE{e98-a_1_61,
author={Yu SASAKI, },
journal={IEICE TRANSACTIONS on Fundamentals},
title={Preimage Attacks on Feistel-SP Functions: Impact of Omitting the Last Network Twist},
year={2015},
volume={E98-A},
number={1},
pages={61-71},
abstract={In this paper, generic attacks are presented against hash functions that are constructed by a hashing mode instantiating a Feistel or generalized Feistel networks with an SP-round function. It is observed that the omission of the network twist in the last round can be a weakness against preimage attacks. The first target is a standard Feistel network with an SP round function. Up to 11 rounds can be attacked in generic if a condition on a key schedule function is satisfied. The second target is a 4-branch type-2 generalized Feistel network with an SP round function. Up to 15 rounds can be attacked in generic. These generic attacks are then applied to hashing modes of ISO standard ciphers Camellia-128 without FL and whitening layers and CLEFIA-128.},
keywords={},
doi={10.1587/transfun.E98.A.61},
ISSN={1745-1337},
month={January},}

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TY - JOUR
TI - Preimage Attacks on Feistel-SP Functions: Impact of Omitting the Last Network Twist
T2 - IEICE TRANSACTIONS on Fundamentals
SP - 61
EP - 71
AU - Yu SASAKI
PY - 2015
DO - 10.1587/transfun.E98.A.61
JO - IEICE TRANSACTIONS on Fundamentals
SN - 1745-1337
VL - E98-A
IS - 1
JA - IEICE TRANSACTIONS on Fundamentals
Y1 - January 2015
AB - In this paper, generic attacks are presented against hash functions that are constructed by a hashing mode instantiating a Feistel or generalized Feistel networks with an SP-round function. It is observed that the omission of the network twist in the last round can be a weakness against preimage attacks. The first target is a standard Feistel network with an SP round function. Up to 11 rounds can be attacked in generic if a condition on a key schedule function is satisfied. The second target is a 4-branch type-2 generalized Feistel network with an SP round function. Up to 15 rounds can be attacked in generic. These generic attacks are then applied to hashing modes of ISO standard ciphers Camellia-128 without FL and whitening layers and CLEFIA-128.
ER -