IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences
Online ISSN : 1745-1337
Print ISSN : 0916-8508
Special Section on Cryptography and Information Security
Security of Multivariate Signature Scheme Using Non-commutative Rings
Takanori YASUDATsuyoshi TAKAGIKouichi SAKURAI
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2014 Volume E97.A Issue 1 Pages 245-252


Multivariate Public Key Cryptosystems (MPKC) are candidates for post-quantum cryptography. Rainbow is a digital signature scheme in MPKC, whose signature generation and verification are relatively efficient. However, the security of MPKC depends on the difficulty in solving a system of multivariate polynomials, and the key length of MPKC becomes substantially large compared with that of RSA cryptosystems for the same level of security. The size of the secret and public keys in MPKC has been reduced in previous research. The NC-Rainbow is a signature scheme in MPKC, which was proposed in order to reduce the size of secret key of Rainbow. So far, several attacks against NC-Rainbow have been proposed. In this paper, we summarize attacks against NC-Rainbow, containing attacks against the original Rainbow, and analyze the total security of NC-Rainbow. Based on the cryptanalysis, we estimate the security parameter of NC-Rainbow at the several security level.

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© 2014 The Institute of Electronics, Information and Communication Engineers
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