BRICS RS-94-38 Damg ˚ ard & Knudsen: Enhancing the Strength of Conventional Cryptosystems BRICS Basic Research in Computer Science Enhancing the Strength of Conventional Cryptosystems Ivan B. Damg ˚ ard Lars Ramkilde Knudsen BRICS Report Series RS-94-38 ISSN 0909-0878 November 1994