Partial Key Exposure Attack on RSA - Improvements for Limited Lattice Dimensions

Abstract. Consider the RSA public key cryptosystem with the parameters N = pq, q < p < 2q, public encryption exponent e and private decryption exponent d. In this paper, cryptanalysis of RSA is studied given that some amount of the Most Significant Bits (MSBs) of d is exposed. In Eurocrypt 2005, a lattice based attack on this problem was proposed by Ernst, Jochemsz, May and de Weger. In this paper, we present a variant of their method which provides better experimental results depending on practical lattice parameters and the values of d. We also propose a sublattice structure that improves the experimental results significantly for smaller decryption exponents.

• Type: Journal
• Year: 2010
• Where: INDOCRYPT
• Authors: Santanu Sarkar, Sourav Sengupta, Subhamoy Maitra
• Keywords: Cryptology, INDOCRYPT 2010, Public Encryption Exponent, Public Key Cryptosystem, Smaller Decryption Exponents