caa a22 4500 475827090 CHVBK 20180406123831.0 cr unu---uuuuu 170329e20000601xx s 000 0 eng 10.1007/s001450010003 doi (NATIONALLICENCE)springer-10.1007/s001450010003 Security Arguments for Digital Signatures and Blind Signatures [Elektronische Daten] [David Pointcheval, Jacques Stern] Abstract. : Since the appearance of public-key cryptography in the seminal Diffie—Hellman paper, many new schemes have been proposed and many have been broken. Thus, the simple fact that a cryptographic algorithm withstands cryptanalytic attacks for several years is often considered as a kind of validation procedure. A much more convincing line of research has tried to provide 's'sprovable'' security for cryptographic protocols. Unfortunately, in many cases, provable security is at the cost of a considerable loss in terms of efficiency. Another way to achieve some kind of provable security is to identify concrete cryptographic objects, such as hash functions, with ideal random objects and to use arguments from relativized complexity theory. The model underlying this approach is often called the 's'srandom oracle model.'' We use the word 's'sarguments'' for security results proved in this model. As usual, these arguments are relative to well-established hard algorithmic problems such as factorization or the discrete logarithm. In this paper we offer security arguments for a large class of known signature schemes. Moreover, we give for the first time an argument for a very slight variation of the well-known El Gamal signature scheme. In spite of the existential forgery of the original scheme, we prove that our variant resists existential forgeries even against an adaptively chosen-message attack. This is provided that the discrete logarithm problem is hard to solve. Next, we study the security of blind signatures which are the most important ingredient for anonymity in off-line electronic cash systems. We first define an appropriate notion of security related to the setting of electronic cash. We then propose new schemes for which one can provide security arguments. International Association for Criptologic Rese, 2000 Key words. Cryptography, Digital signatures, Blind signatures, Security arguments, Existential forgery, One-more forgery, Forking lemma nationallicence Pointcheval David Laboratoire d'Informatique, École Normale Supérieure, 75230 Paris Cedex 05, France David.Pointcheval@ens.fr, Jacques.Stern@ens.fr, http://www.di.ens.fr/~pointche, http://www.di.ens.fr/~stern, FR aut Stern Jacques Laboratoire d'Informatique, École Normale Supérieure, 75230 Paris Cedex 05, France David.Pointcheval@ens.fr, Jacques.Stern@ens.fr, http://www.di.ens.fr/~pointche, http://www.di.ens.fr/~stern, FR aut Journal of Cryptology Springer Berlin Heidelberg 13/3(2000-06-01), 361-396 0933-2790 13:3<361 2000 13 145 https://doi.org/10.1007/s001450010003 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s001450010003 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Pointcheval David Laboratoire d'Informatique, École Normale Supérieure, 75230 Paris Cedex 05, France David.Pointcheval@ens.fr, Jacques.Stern@ens.fr, http://www.di.ens.fr/~pointche, http://www.di.ens.fr/~stern, FR aut NATIONALLICENCE 700 1- Stern Jacques Laboratoire d'Informatique, École Normale Supérieure, 75230 Paris Cedex 05, France David.Pointcheval@ens.fr, Jacques.Stern@ens.fr, http://www.di.ens.fr/~pointche, http://www.di.ens.fr/~stern, FR aut NATIONALLICENCE 773 0- Journal of Cryptology Springer Berlin Heidelberg 13/3(2000-06-01), 361-396 0933-2790 13:3<361 2000 13 145 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer