Cryptology ePrint Archive: Report 2003/221

A Cryptanalysis of the Original Domingo-Ferrer's Algebraic Privacy Homomophism

Jung Hee Cheon and Hyun Soo Nam

Abstract: We propose a cryptanalysis of the original Domingo-Ferrer's algebraic privacy homomorphism. We show that the scheme over $\Z_n$ can be broken by $d+1$ known plaintexts in $O(d^3\log^2 n)$ time when it has $d$ times expansion through the encryption. Furthermore even when the public modulus $n$ is kept secret, it can be broken by $d+2$ known plaintexts in time at most $O(d^5\log^2(dn))$.

Category / Keywords: Privacy homomorphism, Encrypted Data, Database Security

Date: received 12 Oct 2003, last revised 13 Oct 2003

Contact author: hsnam at math snu ac kr

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Version: 20031013:115433 (All versions of this report)

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