Security of the AES with a Secret S-Box

Tyge Tiessen; Lars Ramkilde Knudsen; Stefan Kölbl; Martin Mehl Lauridsen

doi:10.1007/978-3-662-48116-5_9

Security of the AES with a Secret S-Box

Tyge Tiessen, Lars Ramkilde Knudsen, Stefan Kölbl, Martin Mehl Lauridsen

Department of Applied Mathematics and Computer Science

Research output: Chapter in Book/Report/Conference proceeding › Article in proceedings › Research › peer-review

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Abstract

How does the security of the AES change when the S-box is replaced by a secret S-box, about which the adversary has no knowledge? Would it be safe to reduce the number of encryption rounds?

In this paper, we demonstrate attacks based on integral cryptanalysis which allow to recover both the secret key and the secret S-box for respectively four, five, and six rounds of the AES. Despite the significantly larger amount of secret information which an adversary needs to recover, the attacks are very efficient with time/data complexities of 2¹⁷/2¹⁶, 2³⁸/2⁴⁰ and 2⁹⁰/2⁶⁴, respectively.

Another interesting aspect of our attack is that it works both as chosen plaintext and as chosen ciphertext attack. Surprisingly, the chosen ciphertext variant has a significantly lower time complexity in the attacks on four and five round, compared to the respective chosen plaintext attacks.

Original language	English
Title of host publication	Revised Selected Papers of the 22nd International Workshop on Fast Software Encryption (FSE 2015)
Editors	Gregor Leander
Publisher	Springer
Publication date	2015
Pages	175-189
ISBN (Print)	978-3-662-48115-8
ISBN (Electronic)	978-3-662-48116-5
DOIs	https://doi.org/10.1007/978-3-662-48116-5_9
Publication status	Published - 2015
Event	22nd International Workshop on Fast Software Encryption (FSE 2015) - Istanbul, Turkey Duration: 8 Mar 2015 → 11 Mar 2015 Conference number: 22 http://www.lightsec.org/fse2015/

Workshop

Workshop	22nd International Workshop on Fast Software Encryption (FSE 2015)
Number	22
Country/Territory	Turkey
City	Istanbul
Period	08/03/2015 → 11/03/2015
Internet address	http://www.lightsec.org/fse2015/

Keywords

AES
Integral cryptanalysis
Secret S-box

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10.1007/978-3-662-48116-5_9

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title = "Security of the AES with a Secret S-Box",

abstract = "How does the security of the AES change when the S-box is replaced by a secret S-box, about which the adversary has no knowledge? Would it be safe to reduce the number of encryption rounds? In this paper, we demonstrate attacks based on integral cryptanalysis which allow to recover both the secret key and the secret S-box for respectively four, five, and six rounds of the AES. Despite the significantly larger amount of secret information which an adversary needs to recover, the attacks are very efficient with time/data complexities of 217/216, 238/240 and 290/264, respectively. Another interesting aspect of our attack is that it works both as chosen plaintext and as chosen ciphertext attack. Surprisingly, the chosen ciphertext variant has a significantly lower time complexity in the attacks on four and five round, compared to the respective chosen plaintext attacks.",

keywords = "AES, Integral cryptanalysis, Secret S-box",

author = "Tyge Tiessen and Knudsen, \{Lars Ramkilde\} and Stefan K{\"o}lbl and Lauridsen, \{Martin Mehl\}",

year = "2015",

doi = "10.1007/978-3-662-48116-5\_9",

language = "English",

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editor = "Leander, \{Gregor \}",

booktitle = "Revised Selected Papers of the 22nd International Workshop on Fast Software Encryption (FSE 2015)",

publisher = "Springer",

note = "22nd International Workshop on Fast Software Encryption (FSE 2015), FSE 2015 ; Conference date: 08-03-2015 Through 11-03-2015",

url = "http://www.lightsec.org/fse2015/",

}

Tiessen, T, Knudsen, LR, Kölbl, S & Lauridsen, MM 2015, Security of the AES with a Secret S-Box. in G Leander (ed.), Revised Selected Papers of the 22nd International Workshop on Fast Software Encryption (FSE 2015). Springer, pp. 175-189, 22nd International Workshop on Fast Software Encryption (FSE 2015), Istanbul, Turkey, 08/03/2015. https://doi.org/10.1007/978-3-662-48116-5_9

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AU - Lauridsen, Martin Mehl

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PY - 2015

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N2 - How does the security of the AES change when the S-box is replaced by a secret S-box, about which the adversary has no knowledge? Would it be safe to reduce the number of encryption rounds? In this paper, we demonstrate attacks based on integral cryptanalysis which allow to recover both the secret key and the secret S-box for respectively four, five, and six rounds of the AES. Despite the significantly larger amount of secret information which an adversary needs to recover, the attacks are very efficient with time/data complexities of 217/216, 238/240 and 290/264, respectively. Another interesting aspect of our attack is that it works both as chosen plaintext and as chosen ciphertext attack. Surprisingly, the chosen ciphertext variant has a significantly lower time complexity in the attacks on four and five round, compared to the respective chosen plaintext attacks.

AB - How does the security of the AES change when the S-box is replaced by a secret S-box, about which the adversary has no knowledge? Would it be safe to reduce the number of encryption rounds? In this paper, we demonstrate attacks based on integral cryptanalysis which allow to recover both the secret key and the secret S-box for respectively four, five, and six rounds of the AES. Despite the significantly larger amount of secret information which an adversary needs to recover, the attacks are very efficient with time/data complexities of 217/216, 238/240 and 290/264, respectively. Another interesting aspect of our attack is that it works both as chosen plaintext and as chosen ciphertext attack. Surprisingly, the chosen ciphertext variant has a significantly lower time complexity in the attacks on four and five round, compared to the respective chosen plaintext attacks.

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KW - Integral cryptanalysis

KW - Secret S-box

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DO - 10.1007/978-3-662-48116-5_9

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EP - 189

BT - Revised Selected Papers of the 22nd International Workshop on Fast Software Encryption (FSE 2015)

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PB - Springer

T2 - 22nd International Workshop on Fast Software Encryption (FSE 2015)

Y2 - 8 March 2015 through 11 March 2015

ER -

Security of the AES with a Secret S-Box

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Keywords

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