Cryptology ePrint Archive: Report 2002/188

Key recovery attacks on NTRU without ciphertext validation routine

Daewan Han and Jin Hong and Jae Woo Han and Daesung Kwon

Abstract: NTRU is an efficient public-key cryptosystem proposed by Hoffstein, Pipher, and Silverman. Assuming access to a decryption oracle, we show ways to recover the private key of NTRU systems that do not include a ciphertext validating procedure. The strongest of our methods will employ just a single call to the oracle, and in all cases, the number of calls needed will be small enough to be realistic.

Category / Keywords: public-key cryptography / cryptanalysis, NTRU, chosen-ciphertext attack

Date: received 8 Dec 2002, last revised 18 Apr 2003

Contact author: jinhong at bigfoot com

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Version: 20030419:032043 (All versions of this report)

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