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Book Sections Year : 2012

Autotomic Signatures


Digital signature security is classically defined as an interaction between a signer , a verifier and an attacker A . A submits adaptively to a sequence of messages m 1,…,m q to which replies with the signatures U = {σ 1,…,σ q }. Given U, A attempts to produce a forgery, i.e. a pair (m′,σ′) such that and σ′∉U . The traditional approach consists in hardening against a large query bound q. Interestingly, this is one specific way to prevent A from winning the forgery game. This work explores an alternative option. Rather than hardening , we weaken A by preventing him from influencing ’s input: upon receiving m i , will generate a fresh ephemeral signature key-pair , use to sign m i , erase , and output the signature and a certificate on computed using the long-term key . In other words, will only use his permanent secret to sign inputs which are beyond A ’s control (namely, freshly generated public-keys). As the are ephemeral, q = 1 by construction. We show that this paradigm, called autotomic signatures, transforms weakly secure signature schemes (secure against generic attacks only) into strongly secure ones (secure against adaptively chosen-message attacks). As a by-product of our analysis, we show that blending public key information with the signed message can significantly increase security.
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Dates and versions

hal-01110874 , version 1 (29-01-2015)



David Naccache, David Pointcheval. Autotomic Signatures. David Naccache. Cryptography and Security: From Theory to Applications : Essays Dedicated to Jean-Jacques Quisquater on the Occasion of His 65th Birthday, 6805, Springer, pp.143-155, 2012, LNCS - Lecture Notes in Computer Science, 978-3-642-28367-3. ⟨10.1007/978-3-642-28368-0_12⟩. ⟨hal-01110874⟩
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