2021-10-18T23:45:59Zhttps://ipsj.ixsq.nii.ac.jp/ej/?action=repository_oaipmhoai:ipsj.ixsq.nii.ac.jp:001995642019-09-14T15:00:00Z00581:09633:09642
Chosen Message Attack on Multivariate Signature ELSA at Asiacrypt 2017Chosen Message Attack on Multivariate Signature ELSA at Asiacrypt 2017eng[特集：デジタルトランスフォーメーションを加速するコンピュータセキュリティ技術（推薦論文）] post-quantum cryptography, multivariate public-key cryptography, chosen message attack, Rainbow, ELSAhttp://id.nii.ac.jp/1001/00199474/Journal Articlehttps://ipsj.ixsq.nii.ac.jp/ej/?action=repository_action_common_download&item_id=199564&item_no=1&attribute_id=1&file_no=1Copyright (c) 2019 by the Information Processing Society of JapanDepartment of Mathematical Science, University of the RyukyusDepartment of Mathematical Informatics, the University of Tokyo／Presently with Institute of Mathematics for Industry, Kyushu UniversityDepartment of Mathematical Informatics, the University of TokyoYasufumi, HashimotoYasuhiko, IkematsuTsuyoshi, TakagiOne of the most efficient post-quantum signature schemes is Rainbow whose hardness is based on the multivariate quadratic polynomial (MQ) problem. ELSA, a new multivariate signature scheme proposed at Asiacrypt 2017, has a similar construction to Rainbow. Its advantages, compared to Rainbow, are its smaller secret key and faster signature generation. In addition, its existential unforgeability against an adaptive chosen-message attack has been proven under the hardness of the MQ-problem induced by a public key of ELSA with a specific parameter set in the random oracle model. The high efficiency of ELSA is derived from a set of hidden quadratic equations used in the process of signature generation. However, the hidden quadratic equations yield a vulnerability. In fact, a piece of information of these equations can be recovered by using valid signatures and an equivalent secret key can be partially recovered from it. In this paper, we describe how to recover an equivalent secret key of ELSA by a chosen message attack. Our experiments show that we can recover an equivalent secret key for the claimed 128-bit security parameter of ELSA on a standard PC in 177 seconds with 1,326 valid signatures.------------------------------This is a preprint of an article intended for publication Journal ofInformation Processing(JIP). This preprint should not be cited. Thisarticle should be cited as: Journal of Information Processing Vol.27(2019) (online)DOI http://dx.doi.org/10.2197/ipsjjip.27.517------------------------------One of the most efficient post-quantum signature schemes is Rainbow whose hardness is based on the multivariate quadratic polynomial (MQ) problem. ELSA, a new multivariate signature scheme proposed at Asiacrypt 2017, has a similar construction to Rainbow. Its advantages, compared to Rainbow, are its smaller secret key and faster signature generation. In addition, its existential unforgeability against an adaptive chosen-message attack has been proven under the hardness of the MQ-problem induced by a public key of ELSA with a specific parameter set in the random oracle model. The high efficiency of ELSA is derived from a set of hidden quadratic equations used in the process of signature generation. However, the hidden quadratic equations yield a vulnerability. In fact, a piece of information of these equations can be recovered by using valid signatures and an equivalent secret key can be partially recovered from it. In this paper, we describe how to recover an equivalent secret key of ELSA by a chosen message attack. Our experiments show that we can recover an equivalent secret key for the claimed 128-bit security parameter of ELSA on a standard PC in 177 seconds with 1,326 valid signatures.------------------------------This is a preprint of an article intended for publication Journal ofInformation Processing(JIP). This preprint should not be cited. Thisarticle should be cited as: Journal of Information Processing Vol.27(2019) (online)DOI http://dx.doi.org/10.2197/ipsjjip.27.517------------------------------AN00116647情報処理学会論文誌6092019-09-151882-77642019-09-12