Security analysis of the SCO-family using key schedules

Kitae Jeong; Changhoon Lee; Jongsung Kim; Seokhie Hong

doi:10.1016/j.ins.2009.08.009

Security analysis of the SCO-family using key schedules

Kitae Jeong, Changhoon Lee, Jongsung Kim, Seokhie Hong

Research output: Contribution to journal › Article › peer-review

6 Citations (Scopus)

Abstract

The COS-based ciphers SCO-1, SCO-2 and SCO-3 (called the SCO-family) have been designed to improve the security of DDP-based ciphers which are all broken by related-key attacks. In this paper we show that the SCO-family is still vulnerable to related-key attacks: we present related-key differential attacks on a full-round SCO-1, a full-round SCO-2 and an 11-round reduced SCO-3, respectively. The attack on SCO-1 requires 2⁶¹ related-key chosen ciphertexts and 2^120.59 full-round SCO-1 decryptions. For the attack on SCO-2, we require 2⁵⁹ related-key chosen plaintexts and 2^118.42 full-round SCO-2 encryptions, and the 11-round attack on SCO-3 works with 2⁵⁸ related-key chosen plaintexts and 2^117.54 11-round SCO-3 encryptions. This work is the first known cryptanalytic results on the SCO-family.

Original language	English
Pages (from-to)	4232-4242
Number of pages	11
Journal	Information Sciences
Volume	179
Issue number	24
DOIs	https://doi.org/10.1016/j.ins.2009.08.009
Publication status	Published - 2009 Dec 15

Keywords

Block ciphers
Cryptanalysis
Data dependent operation
Related-key differential attack
SCO-1
SCO-2
SCO-3
SCO-family

ASJC Scopus subject areas

Theoretical Computer Science
Software
Control and Systems Engineering
Computer Science Applications
Information Systems and Management
Artificial Intelligence

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10.1016/j.ins.2009.08.009

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title = "Security analysis of the SCO-family using key schedules",

abstract = "The COS-based ciphers SCO-1, SCO-2 and SCO-3 (called the SCO-family) have been designed to improve the security of DDP-based ciphers which are all broken by related-key attacks. In this paper we show that the SCO-family is still vulnerable to related-key attacks: we present related-key differential attacks on a full-round SCO-1, a full-round SCO-2 and an 11-round reduced SCO-3, respectively. The attack on SCO-1 requires 261 related-key chosen ciphertexts and 2120.59 full-round SCO-1 decryptions. For the attack on SCO-2, we require 259 related-key chosen plaintexts and 2118.42 full-round SCO-2 encryptions, and the 11-round attack on SCO-3 works with 258 related-key chosen plaintexts and 2117.54 11-round SCO-3 encryptions. This work is the first known cryptanalytic results on the SCO-family.",

keywords = "Block ciphers, Cryptanalysis, Data dependent operation, Related-key differential attack, SCO-1, SCO-2, SCO-3, SCO-family",

author = "Kitae Jeong and Changhoon Lee and Jongsung Kim and Seokhie Hong",

note = "Funding Information: This work was supported by Hanshin University Research Grant and the Second Brain Korea 21 Project. ",

year = "2009",

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doi = "10.1016/j.ins.2009.08.009",

language = "English",

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AU - Jeong, Kitae

AU - Lee, Changhoon

AU - Kim, Jongsung

AU - Hong, Seokhie

N1 - Funding Information: This work was supported by Hanshin University Research Grant and the Second Brain Korea 21 Project.

PY - 2009/12/15

Y1 - 2009/12/15

N2 - The COS-based ciphers SCO-1, SCO-2 and SCO-3 (called the SCO-family) have been designed to improve the security of DDP-based ciphers which are all broken by related-key attacks. In this paper we show that the SCO-family is still vulnerable to related-key attacks: we present related-key differential attacks on a full-round SCO-1, a full-round SCO-2 and an 11-round reduced SCO-3, respectively. The attack on SCO-1 requires 261 related-key chosen ciphertexts and 2120.59 full-round SCO-1 decryptions. For the attack on SCO-2, we require 259 related-key chosen plaintexts and 2118.42 full-round SCO-2 encryptions, and the 11-round attack on SCO-3 works with 258 related-key chosen plaintexts and 2117.54 11-round SCO-3 encryptions. This work is the first known cryptanalytic results on the SCO-family.

AB - The COS-based ciphers SCO-1, SCO-2 and SCO-3 (called the SCO-family) have been designed to improve the security of DDP-based ciphers which are all broken by related-key attacks. In this paper we show that the SCO-family is still vulnerable to related-key attacks: we present related-key differential attacks on a full-round SCO-1, a full-round SCO-2 and an 11-round reduced SCO-3, respectively. The attack on SCO-1 requires 261 related-key chosen ciphertexts and 2120.59 full-round SCO-1 decryptions. For the attack on SCO-2, we require 259 related-key chosen plaintexts and 2118.42 full-round SCO-2 encryptions, and the 11-round attack on SCO-3 works with 258 related-key chosen plaintexts and 2117.54 11-round SCO-3 encryptions. This work is the first known cryptanalytic results on the SCO-family.

KW - Block ciphers

KW - Cryptanalysis

KW - Data dependent operation

KW - Related-key differential attack

KW - SCO-1

KW - SCO-2

KW - SCO-3

KW - SCO-family

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DO - 10.1016/j.ins.2009.08.009

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SN - 0020-0255

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SP - 4232

EP - 4242

JO - Information Sciences

JF - Information Sciences

IS - 24

ER -

Security analysis of the SCO-family using key schedules

Abstract

Keywords

ASJC Scopus subject areas

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