By carefully measuring the amount of time required to perform private key operations, attackers may be able to nd xed Di eHellman exponents, factor RSA keys, and break other cryptosystems. Against a vulnerable system, the attack is computationally inexpensive and often requires only known ciphertext. Actual systems are potentially at risk, including cryptographic tokens, network-based cryptosys...

ElGamal cryptosystem is one of the oldest public-key cryptosystems. It is known to be semantically secure for arbitrary messages in the random oracle model under the decisional Diffie-Hellman assumption. Semantic security also holds in the standard model when messages are encoded as elements in the group for which the decisional Diffie-Hellman assumption is defined. This paper introduces a sett...

A property of the NTRU public-key cryptosystem is that it does not provide perfect decryption. That is, given an instance of the cryptosystem, there exist ciphertexts which can be validly created using the public key but which can’t be decrypted using the private key. The valid ciphertexts which an NTRU secret key will not correctly decipher determine, up to a cyclic shift, the secret key. In t...

In this paper we propose two public key BE schemes that have efficient complexity measures. The first scheme, called the PBE-PI scheme, has O(r) header size, O(1) public keys and O(log N) private keys per user, where r is the number of revoked users. This is the first public key BE scheme that has both public and private keys under O(log N) while the header size is O(r). These complexity measur...

We present a public-key encryption scheme which is provably secure against adaptive chosen ciphertext attack. The scheme is constructed using Cramer-Shoup paradigm [7]. The security of the scheme is based on the Decisional Bilinear Diffie-Hellman problem.

A peer-to-peer database management system(P2PDBMS) is a collection of autonomous data sources, called peers. In this system each peer augments a conventional database management system with an inter-operability layer (i.e. mappings/policies) for sharing data and services. Peers exchange data in a pair-wise fashion on-the-fly in response to a query without any centralized control. Generally, the...

We proposed a new public-key traitor tracing scheme with revocation capability using the dynamic share and entity revocation techniques. The enabling block of our scheme is independent of the number of subscribers, but dependent on the collusion and revocation thresholds. Each receiver holds one decryption key only. Our traitor tracing algorithm works in a black-box way and is conceptually simp...

SUMMARY In the execution on a smart card, side channel attacks such as the simple power analysis (SPA) and the differential power analysis (DPA) have become serious threat. Side channel attacks monitor the side channel information such as power consumption and even exploit the leakage information related to power consumption to reveal bits of a secret key d although d is hidden inside a smart c...

Recently, a few chosen-ciphertext secure (CCA2-secure) variants of the McEliece public-key encryption (PKE) scheme in the standard model were introduced. All the proposed schemes are based on encryption repetition paradigm and use general transformation from CPAsecure scheme to a CCA2-secure one. Therefore, the resulting encryption scheme needs separate encryption and has large key size compare...

We present a non-interactive chosen ciphertext secure threshold encryption system. The proof of security is set in the standard model and does not use random oracles. Our construction uses the recent identity based encryption system of Boneh and Boyen and the chosen ciphertext secure construction of Canetti, Halevi, and Katz.