Résumé

The Digital Signature Algorithm (DSA) was proposed in 1991 by the US National Institute of Standards and Technology to provide an appropriate core for applications requiring digital signatures. Undoubtedly, many applications will include this standard in the future and thus, the foreseen domination of DSA as a legal certification tool is sufficiently important to focus research endeavours on the suitability of this scheme to various situations. In this paper, we present six new DSA-based protocols for: 1. Performing a quick batch-verification of n signatures. The proposed scheme allows the economy of ≈ 450n modular multiplications. 2. Avoiding the cumbersome calculation of 1/k mod q by the signer. 3. Compressing sets of DSA transactions into shorter archive signatures. Generating signatures from pre-calculated “use & throw” 224-bit signature-coupons. 4. Self-certifying the moduli and bit-patterning directly q on p (gain of 60.4% in key size). All our schemes combine in a natural way full DSA compatibility and flexible trade-offs between computational complexity, transmission overheads and key sizes

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