On the Security of RSA with Primes Sharing Least-Significant Bits

  • Authors:
  • Ron Steinfeld;Yuliang Zheng

  • Affiliations:
  • Macquarie University, Department of Computing, 2109, North Ryde, NSW, Australia;University of North Carolina at Charlotte, Department of Software and Information Systems, 28223, Charlotte, NC, USA

  • Venue:
  • Applicable Algebra in Engineering, Communication and Computing
  • Year:
  • 2004

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Abstract

We investigate the security of a variant of the RSA public-key cryptosystem called LSBS-RSA, in which the modulus primes share a large number of least-significant bits. We show that low public-exponent LSBS-RSA is inherently resistant to Partial Key Exposure (PKE) attacks in which least-significant bits of the secret exponent are revealed to the attacker, and in particular that the Boneh-Durfee-Frankel PKE attack [5] on low public-exponent RSA is less effective for LSBS-RSA systems than for standard RSA. On the other hand, we show that large public-exponent LSBS-RSA is more vulnerable to such attacks than standard RSA. An application to server-aided RSA signature generation is proposed.