Initial observations on skipjack: Cryptanalysis of skipjack-3XOR

Eli Biham; Alex Biryukov; Orr Dunkelman; Eran Richardson; Adi Shamir

doi:10.1007/3-540-48892-8_27

Initial observations on skipjack: Cryptanalysis of skipjack-3XOR

Eli Biham, Alex Biryukov, Orr Dunkelman, Eran Richardson, Adi Shamir

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

Abstract

Skipjack is the secret key encryption algorithm developed by the NSA for the Clipper chip and Fortezza PC card. It uses an 80-bit key, 128 table lookup operations, and 320 XOR operations to map a 64-bit plaintext into a 64-bit ciphertext in 32 rounds. This paper describes an efficient attack on a variant, which we call Skipjack- 3XOR (Skipjack minus 3 XORs). The only difference between Skipjack and Skipjack-3XOR is the removal of 3 out of the 320 XOR operations. The attack uses the ciphertexts derived from about 500 plaintexts and its total running time is equivalent to about one million Skipjack encryptions, which can be carried out in seconds on a personal computer. We also present a new cryptographic tool, which we call the Yoyo game, and efficient attacks on Skipjack reduced to 16 rounds. We conclude that Skipjack does not have a conservative design with a large margin of safety.

Original language	English
Title of host publication	Selected Areas in Cryptography - 5th Annual International Workshop, SAC 1998, Proceedings
Editors	Stafford Tavares, Henk Meijer
Publisher	Springer Verlag
Pages	362-375
Number of pages	14
ISBN (Print)	3540658947, 9783540658948
DOIs	https://doi.org/10.1007/3-540-48892-8_27
State	Published - 1999
Externally published	Yes
Event	5th Annual Workshops on Selected Areas in Cryptography, SAC 1998 - Kingston, Canada Duration: 17 Aug 1998 → 18 Aug 1998

Publication series

Name	Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume	1556
ISSN (Print)	0302-9743
ISSN (Electronic)	1611-3349

Conference

Conference	5th Annual Workshops on Selected Areas in Cryptography, SAC 1998
Country/Territory	Canada
City	Kingston
Period	17/08/98 → 18/08/98

Bibliographical note

Publisher Copyright:
© Springer-Verlag Berlin Heidelberg 1999.

Keywords

Clipper chip
Cryptanalysis
Fortezza PC card
Skipjack
Yoyo game

ASJC Scopus subject areas

Theoretical Computer Science
General Computer Science

Access to Document

10.1007/3-540-48892-8_27

Cite this

Biham, E., Biryukov, A., Dunkelman, O., Richardson, E., & Shamir, A. (1999). Initial observations on skipjack: Cryptanalysis of skipjack-3XOR. In S. Tavares, & H. Meijer (Eds.), Selected Areas in Cryptography - 5th Annual International Workshop, SAC 1998, Proceedings (pp. 362-375). (Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics); Vol. 1556). Springer Verlag. https://doi.org/10.1007/3-540-48892-8_27

Biham, Eli ; Biryukov, Alex ; Dunkelman, Orr et al. / Initial observations on skipjack : Cryptanalysis of skipjack-3XOR. Selected Areas in Cryptography - 5th Annual International Workshop, SAC 1998, Proceedings. editor / Stafford Tavares ; Henk Meijer. Springer Verlag, 1999. pp. 362-375 (Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)).

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abstract = "Skipjack is the secret key encryption algorithm developed by the NSA for the Clipper chip and Fortezza PC card. It uses an 80-bit key, 128 table lookup operations, and 320 XOR operations to map a 64-bit plaintext into a 64-bit ciphertext in 32 rounds. This paper describes an efficient attack on a variant, which we call Skipjack- 3XOR (Skipjack minus 3 XORs). The only difference between Skipjack and Skipjack-3XOR is the removal of 3 out of the 320 XOR operations. The attack uses the ciphertexts derived from about 500 plaintexts and its total running time is equivalent to about one million Skipjack encryptions, which can be carried out in seconds on a personal computer. We also present a new cryptographic tool, which we call the Yoyo game, and efficient attacks on Skipjack reduced to 16 rounds. We conclude that Skipjack does not have a conservative design with a large margin of safety.",

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author = "Eli Biham and Alex Biryukov and Orr Dunkelman and Eran Richardson and Adi Shamir",

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doi = "10.1007/3-540-48892-8_27",

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Biham, E, Biryukov, A, Dunkelman, O, Richardson, E & Shamir, A 1999, Initial observations on skipjack: Cryptanalysis of skipjack-3XOR. in S Tavares & H Meijer (eds), Selected Areas in Cryptography - 5th Annual International Workshop, SAC 1998, Proceedings. Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), vol. 1556, Springer Verlag, pp. 362-375, 5th Annual Workshops on Selected Areas in Cryptography, SAC 1998, Kingston, Canada, 17/08/98. https://doi.org/10.1007/3-540-48892-8_27

Initial observations on skipjack: Cryptanalysis of skipjack-3XOR. / Biham, Eli; Biryukov, Alex; Dunkelman, Orr et al.
Selected Areas in Cryptography - 5th Annual International Workshop, SAC 1998, Proceedings. ed. / Stafford Tavares; Henk Meijer. Springer Verlag, 1999. p. 362-375 (Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics); Vol. 1556).

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

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N2 - Skipjack is the secret key encryption algorithm developed by the NSA for the Clipper chip and Fortezza PC card. It uses an 80-bit key, 128 table lookup operations, and 320 XOR operations to map a 64-bit plaintext into a 64-bit ciphertext in 32 rounds. This paper describes an efficient attack on a variant, which we call Skipjack- 3XOR (Skipjack minus 3 XORs). The only difference between Skipjack and Skipjack-3XOR is the removal of 3 out of the 320 XOR operations. The attack uses the ciphertexts derived from about 500 plaintexts and its total running time is equivalent to about one million Skipjack encryptions, which can be carried out in seconds on a personal computer. We also present a new cryptographic tool, which we call the Yoyo game, and efficient attacks on Skipjack reduced to 16 rounds. We conclude that Skipjack does not have a conservative design with a large margin of safety.

AB - Skipjack is the secret key encryption algorithm developed by the NSA for the Clipper chip and Fortezza PC card. It uses an 80-bit key, 128 table lookup operations, and 320 XOR operations to map a 64-bit plaintext into a 64-bit ciphertext in 32 rounds. This paper describes an efficient attack on a variant, which we call Skipjack- 3XOR (Skipjack minus 3 XORs). The only difference between Skipjack and Skipjack-3XOR is the removal of 3 out of the 320 XOR operations. The attack uses the ciphertexts derived from about 500 plaintexts and its total running time is equivalent to about one million Skipjack encryptions, which can be carried out in seconds on a personal computer. We also present a new cryptographic tool, which we call the Yoyo game, and efficient attacks on Skipjack reduced to 16 rounds. We conclude that Skipjack does not have a conservative design with a large margin of safety.

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ER -

Biham E, Biryukov A, Dunkelman O, Richardson E, Shamir A. Initial observations on skipjack: Cryptanalysis of skipjack-3XOR. In Tavares S, Meijer H, editors, Selected Areas in Cryptography - 5th Annual International Workshop, SAC 1998, Proceedings. Springer Verlag. 1999. p. 362-375. (Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)). doi: 10.1007/3-540-48892-8_27

Initial observations on skipjack: Cryptanalysis of skipjack-3XOR

Abstract

Publication series

Conference

Bibliographical note

Keywords

ASJC Scopus subject areas

Access to Document

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