A primitive or protocol with provable security is accompanied by a mathematical proof that shows how to reduce the security claims about the protocol to a set of assumptions.

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Why does NTRUEncrypt lack a formal security proof?

Is there any particular reason why NTRUEncrypt lacks a formal security proof? That is, a demonstration that it achieves certain security notion (e.g. IND-CPA). I know there is a provable-secure ...
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65 views

Key escrow on indistinguishability games

Does it mean that when PPT attacker is breaking an indistinguishable based (equivalent with semantic security) game with non negligible probability that he is able to infer the secret keys either on ...
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144 views

Is this chat protocol safe?

I am in the design phase of a secure chat application at the moment. I am trying to make this as secure as possible. The Serverprovider should not have access to the messagedata. So my idea was the ...
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Bridging the gap between security proofs and “real-world” security

I've been studying cryptography for a little while. I understand fairly well the nuts and bolts of security proofs, but I'm having trouble reconciling the formal statements of security in these proofs ...
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150 views

Is this modified Schnorr signature scheme secure?

Signing Let y = g^x, which is your public/private keypair. Let r = g^v, for random v Let c = H(M) Let z = (v + cx) mod q The signature is the pair (r,z) Verifying g^z = ry^c mod p We further ...
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Privacy-Preserving Protocols and Proofs of Security

While dabbling in privacy-preserving protocols (mainly using Semi-Homomorphic Encryption) and coming up with miscellaneous ideas for comparison tests or other similar primitives, based on obfuscation ...
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217 views

How to prove Security of Onion Layers of encryption?

CryptDB has Onion layers of Encryption to provide wider functionality from weaker forms of encryption. How do we prove such things are indeed secure ? Intuitively It seems ok. Are there any parallels ...
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Hard problems in composite order group even when factorization is known

Composite discrete log problem has been proved to be reducible to hardness of factorization and discrete log on the prime factor groups. Are there any problems apart from that in composite order ...
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What is the restriction on k, for the kth composite residuosity problem to be hard

This paper considers the exponent to be an odd integer. When k = 2, it is called the quadratic residuosity problem (mod n where n is composite) which is hard and can be solved if the factorization of ...
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Proof for composed signatures

Assumes that we have 3 signature algorithms, $S^A$ with key pair $(sk^A,pk^A)$, $S^B$ with key pair $(sk^B,pk^B)$,$S^C$ with key pair $(sk^C,pk^C)$. We denote by $\epsilon$, $\epsilon'$ and ...
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OCB and GCM security

Is OCB as secure as GCM or CCM ? Since OCB design is quite different from GCM and CCM, I was wondering if the security properties of these latters are satisfied by OCB, as well. Thank you.