Results 1 - 10 of 86

Obfuscation ⇒ (IND-CPA Security ⇒ Circular Security)

by Antonio Marcedone, Claudio Orl , 2013
"... Abstract Circular security is an important notion for public-key encryption schemes and is needed by several cryptographic protocols. In circular security the adversary is given an extra “hint ” consisting of a cycle of encryption of secret keys i.e., (Epk1(sk2),..., Epkn(sk1)). A natural question i ..."
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is whether every IND-CPA encryption scheme is also circular secure. It is trivial to see that this is not the case when n = 1. In 2010 a separation for n = 2 was shown by [ABBC10,GH10] under standard assumptions in bilinear groups. In this paper we finally settle the question showing that for every n

Standard Security Does Imply Security Against Selective Opening for Markov Distributions

by Georg Fuchsbauer, Felix Heuer, Eike Kiltz, Krzysztof Pietrzak
"... About three decades ago it was realized that implementing private channels between parties which can be adaptively corrupted requires an encryption scheme that is secure against selective opening attacks. Whether standard (IND-CPA) security implies security against selective opening attacks has been ..."
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About three decades ago it was realized that implementing private channels between parties which can be adaptively corrupted requires an encryption scheme that is secure against selective opening attacks. Whether standard (IND-CPA) security implies security against selective opening attacks has

Short (resp. Fast) CCA2-Fully-Anonymous Group Signatures Using IND-CPA-Encrypted Escrows

by Victor K. Wei , 2005
"... In the newest and strongest security models for group signatures [7, 10, 41], attackers are given the capability to query an Open Oracle, in order to obtain the signer identity of the queried signature. This oracle mirrors the Decryption Oracle in security experiments involving encryption sche ..."
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signature can be constructed using only IND-CPA-secure encryptions. Here, we settle this issue in the positive by constructing CCA2-fully-anonymous group signatures from IND-CPA-secure encryptions for the OA, without ever using IND-CCA2-secure encryptions. Our technique uses a single ElGamal or similar

Hedged Public-Key Encryption: How to Protect against Bad Randomness

by Mihir Bellare, Zvika Brakerski, Moni Naor, Thomas Ristenpart, Gil Segev, Hovav Shacham, Scott Yilek - IACR EPRINT , 2012
"... Public-key encryption schemes rely for their IND-CPA security on per-message fresh randomness. In practice, randomness may be of poor quality for a variety of reasons, leading to failure of the schemes. Expecting the systems to improve is unrealistic. What we show in this paper is that we can, inste ..."
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Public-key encryption schemes rely for their IND-CPA security on per-message fresh randomness. In practice, randomness may be of poor quality for a variety of reasons, leading to failure of the schemes. Expecting the systems to improve is unrealistic. What we show in this paper is that we can

Separations in Circular Security for Arbitrary Length Key Cycles

by Brent Waters, Kim Ramchen
"... While standard notions of security suffice to protect any message supplied by an adversary, in some situations stronger notions of security are required. One such notion is n-circular security, where ciphertexts Enc(pk 1, sk2), Enc(pk 2, sk3),..., Enc(pk n, sk1) should be indistinguishable from encr ..."
Abstract - Cited by 8 (1 self) - Add to MetaCart
encryptions of zero. In this work we prove the following results for n-circular security: • For any n there exists an encryption scheme that is IND-CPA secure but not n-circular secure. • There exists a bit encryption scheme that is IND-CPA secure, but not 1-circular secure. • If there exists an encryption

Bounded CCA2-secure encryption

by Ronald Cramer, Goichiro Hanaoka, Dennis Hofheinz, Hideki Imai, Eike Kiltz, Rafael Pass, Abhi Shelat, Vinod Vaikuntanathan - In Advances in Cryptology - ASIACRYPT ’07 , 2007
"... Abstract. Whereas encryption schemes withstanding passive chosenplaintext attacks (CPA) can be constructed based on a variety of computational assumptions, only a few assumptions are known to imply the existence of encryption schemes withstanding adaptive chosen-ciphertext attacks (CCA2). Towards ad ..."
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polynomial q, a (non-black box) construction of q-bounded NM-CCA2-secure encryption schemes, from any IND-CPA-secure encryption scheme. Bounded-CCA2 non-malleability is the strongest notion of security yet known to be achievable assuming only the existence of IND-CPA secure encryption schemes. Finally, we

On FHE Without Bootstrapping (Informal)

by Aayush Jain , 2013
"... In this work we come up with two fully homomorphic schemes. First, we propose an IND-CPA secure symmetric key homomorphic encryption scheme using multivariate polynomial ring over finite fields. This scheme gives a method of constructing a CPA secure homomorphic encryption scheme from another symm ..."
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In this work we come up with two fully homomorphic schemes. First, we propose an IND-CPA secure symmetric key homomorphic encryption scheme using multivariate polynomial ring over finite fields. This scheme gives a method of constructing a CPA secure homomorphic encryption scheme from another

HELEN: a Public-key Cryptosystem Based on the LPN and the Decisional Minimal Distance Problems

by Alexandre Duc, Serge Vaudenay
"... We propose HELEN, a code-based public-key cryptosystem whose security is based on the hardness of the Learning from Parity with Noise problem (LPN) and the decisional minimum distance problem. We show that the resulting cryptosystem achieves indistinguishability under chosen plaintext attacks (IND ..."
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(IND-CPA security). Using the Fujisaki-Okamoto generic construction, HELEN achieves IND-CCA security in the random oracle model. Our cryptosystem looks like the Alekhnovich cryptosystem. However, we carefully study its complexity and we further propose concrete optimized parameters.

Public Key Locally Decodable Codes with Short Keys

by Brett Hemenway, Rafail Ostrovsky, et al. , 2011
"... This work considers locally decodable codes in the computationally bounded channel model. The computationally bounded channel model, introduced by Lipton in 1994, views the channel as an adversary which is restricted to polynomial-time computation. Assuming the existence of IND-CPA secure public-key ..."
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This work considers locally decodable codes in the computationally bounded channel model. The computationally bounded channel model, introduced by Lipton in 1994, views the channel as an adversary which is restricted to polynomial-time computation. Assuming the existence of IND-CPA secure public

Computationally Sound Analysis of Protocols using Bilinear Pairings

by Laurent Mazaré , 2007
"... In this paper, we introduce a symbolic model to analyse protocols that use a bilinear pairing between two cyclic groups. This model consists in an extension of the Abadi-Rogaway logic and we prove that the logic is still computationally sound: symbolic indistinguishability implies computational ind ..."
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indistinguishability provided that the Bilinear Decisional Diffie-Hellman assumption holds and that the encryption scheme is IND-CPA secure. We illustrate our results on classical protocols using bilinear pairing like Joux tripartite Diffie-Hellman protocol or the TAK-2 and TAK-3 protocols.
Results 1 - 10 of 86