Description
We focus on two new number-theoretic problems of major importance for RSA and factoring-based cryptosystems. An RSA key generator Gen(1^k) = (n, e) is malleable when factoring n is easier when given access to a factoring oracle for other keys (n', e')!= (n, e) output by Gen. Gen is instance-malleable when it is easier to extract e-th roots mod n given an e'-th root extractor mod n' for (n', e') != (n , e) output by Gen. Instance-non-malleable generators are of prime importance for practical RSA-based systems (RSA-PSS, RSA-OAEP, etc) because their security can be shown not to be equivalent to RSA in the standard model, in contradiction with the random oracle heuristic. We investigate the malleability and instance-malleability of popular RSA key generators such as textbook RSA and low-exponent RSA and question the existence of non-trivial malleable RSA instances.
Next sessions
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Encryption homomorphe sans bruit à l'aide de groupes
Speaker : Pierre Guillot - Ravel Technologies (dispo Université de Strasbourg, IRMA)
Je vais rappeler les travaux de Nuida et Ostrovski sur l'utilisation des groupes pour l'élaboration de schémas cryptographiques homomorphes. Je vais présenter nos travaux qui fournissent des encodages à la fois plus efficaces et plus généraux, et qui déterminent exactement quels groupes peuvent être utilisés. Puis je vais discuter GRAFHEN, un protocole qui utilise ces idées. Je dirai juste[…]-
Cryptography
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