Equivalent keys in ℳultivariate uadratic public key systems

ℳultivariate uadratic public key schemes have been suggested as early as 1985 by Matsumoto and Imai as an alternative for the RSA scheme. Since then, several schemes have been proposed, for example hidden field equations, unbalanced oil and vinegar schemes, and stepwise triangular schemes. All these...

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Main Authors: Wolf Christopher, Preneel Bart
Format: Article
Language:English
Published: De Gruyter 2011-04-01
Series:Journal of Mathematical Cryptology
Subjects:
Online Access:https://doi.org/10.1515/jmc.2011.004
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author Wolf Christopher
Preneel Bart
author_facet Wolf Christopher
Preneel Bart
author_sort Wolf Christopher
collection DOAJ
description ℳultivariate uadratic public key schemes have been suggested as early as 1985 by Matsumoto and Imai as an alternative for the RSA scheme. Since then, several schemes have been proposed, for example hidden field equations, unbalanced oil and vinegar schemes, and stepwise triangular schemes. All these schemes have a rather large key space for a secure choice of parameters. Surprisingly, the question of equivalent keys has not been discussed in the open literature until recently. In this article, we show that for all basic classes mentioned above, it is possible to reduce the private – and hence the public – key space by several orders of magnitude, i.e. the size of the set of possible private and hence public keys can be reduced. For the Matsumoto–Imai scheme, we are even able to show that the reductions we found are the only ones possible, i.e. that these reductions are tight. While the theorems developed in this article are of independent interest themselves as they broaden our understanding of ℳultivariate uadratic public key systems, we see applications of our results both in cryptanalysis and in memory efficient implementations of -schemes.
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spelling doaj.art-0dd1135c883b48d5a11f09891bc03c282022-12-22T04:10:11ZengDe GruyterJournal of Mathematical Cryptology1862-29761862-29842011-04-014437541510.1515/jmc.2011.004Equivalent keys in ℳultivariate uadratic public key systemsWolf Christopher0Preneel Bart1K. U. Leuven, ESAT-COSIC, Kasteelpark Arenberg 10, BE-3001 Leuven-Heverlee, Belgium; and Horst Görtz Institute for IT-Security, Building NA 5/69, Ruhr-University Bochum, DE-44780 Bochum, Germany. K.U. Leuven, ESAT-COSIC, Kasteelpark Arenberg 10, BE-3001 Leuven-Heverlee, Belgium.ℳultivariate uadratic public key schemes have been suggested as early as 1985 by Matsumoto and Imai as an alternative for the RSA scheme. Since then, several schemes have been proposed, for example hidden field equations, unbalanced oil and vinegar schemes, and stepwise triangular schemes. All these schemes have a rather large key space for a secure choice of parameters. Surprisingly, the question of equivalent keys has not been discussed in the open literature until recently. In this article, we show that for all basic classes mentioned above, it is possible to reduce the private – and hence the public – key space by several orders of magnitude, i.e. the size of the set of possible private and hence public keys can be reduced. For the Matsumoto–Imai scheme, we are even able to show that the reductions we found are the only ones possible, i.e. that these reductions are tight. While the theorems developed in this article are of independent interest themselves as they broaden our understanding of ℳultivariate uadratic public key systems, we see applications of our results both in cryptanalysis and in memory efficient implementations of -schemes.https://doi.org/10.1515/jmc.2011.004ℳultivariate uadratic polynomialspublic key signaturehidden field equationsmatsumoto–imai scheme a, c*unbalanced oil and vinegarstepwise triangular systemsequivalent keyspost-quantum cryptography
spellingShingle Wolf Christopher
Preneel Bart
Equivalent keys in ℳultivariate uadratic public key systems
Journal of Mathematical Cryptology
ℳultivariate uadratic polynomials
public key signature
hidden field equations
matsumoto–imai scheme a, c*
unbalanced oil and vinegar
stepwise triangular systems
equivalent keys
post-quantum cryptography
title Equivalent keys in ℳultivariate uadratic public key systems
title_full Equivalent keys in ℳultivariate uadratic public key systems
title_fullStr Equivalent keys in ℳultivariate uadratic public key systems
title_full_unstemmed Equivalent keys in ℳultivariate uadratic public key systems
title_short Equivalent keys in ℳultivariate uadratic public key systems
title_sort equivalent keys in multivariate uadratic public key systems
topic ℳultivariate uadratic polynomials
public key signature
hidden field equations
matsumoto–imai scheme a, c*
unbalanced oil and vinegar
stepwise triangular systems
equivalent keys
post-quantum cryptography
url https://doi.org/10.1515/jmc.2011.004
work_keys_str_mv AT wolfchristopher equivalentkeysinmultivariateuadraticpublickeysystems
AT preneelbart equivalentkeysinmultivariateuadraticpublickeysystems