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In a recent preprint, Vivek et al. propose a compiler to transform a passively secure 3-party key establishment to a passively secure group key establishment. To achieve active security, they apply this compiler to Joux΄s protocol and apply a construction by Katz and Yung, resulting in a 3-round group key establishment. In this paper we show how Joux΄s protocol can be extended to an actively secure group key establishment with two rounds. The resulting solution is in the standard model, builds on a bilinear Diffie-Hellman assumption and offers forward security as well as strong entity authentication. If strong entity authentication is not required, then one half of the participants does not have to send any message in the second round, which may be of interest for scenarios where communication efficiency is a main concern. [ABSTRACT FROM AUTHOR]

We envision a portable device-centric streaming service system. To cope with the demand for displaying contents stored in a portable device onto a high resolution display device, our system provides an autonomous and seamless device-centric streaming service model. As this model takes pairing phase via Bluetooth and streaming phase via broad band network, consumers do not need to know about specific information of nearby systems for streaming. Along with the user convenience, this approach saves battery power by yielding decoding and frame scaling to the better external device. This promises great convenience for users of HD video recordable consumer electronics. [ABSTRACT FROM AUTHOR]

Binary biometric representations have great significance for data compression and template protection. In this paper, we introduce pairwise polar quantization. Furthermore, aiming to optimize the discrimination between the genuine Hamming distance (GHD) and the imposter Hamming distance (IHD), we propose two feature pairing strategies: the long-short (LS) strategy for phase quantization, as well as the long-long (LL) strategy for magnitude quantization. Experimental results for the FRGC face database and the FVC2000 fingerprint database show that phase bits provide reasonably good performance, whereas magnitude bits obtain poor performance. [ABSTRACT FROM AUTHOR]

In this paper, we propose a variant of the Pollard rho method. We use an iterating function whose image size is much smaller than its domain and hence reaches a collision faster than the original iterating function. We also explicitly show how this general method can be applied to multiplicative subgroups of finite fields with large extension degree. The construction for finite fields uses a distinctive feature of the normal basis representation, namely, that the p-th power of an element is just the cyclic shift of its normal basis representation, when the underlying field is of characteristic p. This makes our method appropriate for hardware implementations. On multiplicative subgroups of ]> , our method shows time complexity advantage over the original Pollard rho method by a factor of approximately ]> . Through the MOV reduction, our method can be applied to pairing-based cryptosystems over binary or ternary fields. Hence our algorithm suggests that the order of subgroups, on which the pairing-based cryptosystems rely, needs to be increased by a factor of approximately m. [ABSTRACT FROM AUTHOR]

Pairings over elliptic curves use fields ]> with p ≥ 2160 and 6 < k ≤ 32. In this paper we propose to represent elements in ]> with AMNS sytem of [1]. For well chosen AMNS we get roots of unity with sparse representation. The multiplication by these roots are thus really efficient in ]> . The DFT/FFT approach for multiplication in extension field ]> is thus optimized. The resulting complexity of a multiplication in ]> combining AMNS and DFT is about 50% less than the previously recommended approach [2]. [ABSTRACT FROM AUTHOR]

In this paper, we propose the concept of a relinkable ring signature, which is a ring signature with ring reformation function, i.e., a signer can delegate ring reformation ability separately from signing ability to his/her proxy. The relinkable ring signature can be applicable to proxy ring reformation, anonymization of past-generated signature, or ring signature for dynamic group. We also propose a concrete relinkable ring signature scheme that uses pairing in the random oracle model. [ABSTRACT FROM AUTHOR]

When we implement the ηT pairing, which is one of the fastest pairings, we need multiplications in a base field ]> and in a group G. We have previously regarded elements in G as those in ]> to implement the ηT pairing. Gorla et al. proposed a multiplication algorithm in ]> that takes 5 multiplications in ]> , namely 15 multiplications in ]> . This algorithm then reaches the theoretical lower bound of the number of multiplications. On the other hand, we may also regard elements in G as those in the residue group ]> in which βa is equivalent to a for ]> and ]> . This paper proposes an algorithm for computing a multiplication in the residue group. Its cost is asymptotically 12 multiplications in ]> as m → ∞, which reaches beyond the lower bound the algorithm of Gorla et al. reaches. The proposed algorithm is especially effective when multiplication in the finite field is implemented using a basic method such as shift-and-add. [ABSTRACT FROM AUTHOR]

An anonymous credential-based access control system allows the user to prove possession of credentials to a resource guard that enforce access policies on one or more resources, whereby interactions involving the same user are unlinkable by the resource guard. This paper proposes three fast batch verifiable anonymous credential schemes. With all three schemes, the user can arbitrarily choose a portion of his access rights to prove possession of credentials while the number of expensive cryptographic computations spent is independent of the number of accessx rights being chosen. Moreover, the third anonymous credential scheme is not only fast batch verifiable but also fast fine-grained revocable, which means that to verify whether an arbitrarily chosen subset of credentials is revoked entails constant computation cost. [ABSTRACT FROM AUTHOR]

More and more customers are outsourcing data storage to remote archive service providers that are responsible for properly preserving the data. As such, it has become crucial for an archive service to be capable of providing evidence to demonstrate the integrity of data for which it is responsible, from the time it receives the data until the expiration of the archival period. Pairing-based provable data integrity (PDI) scheme is proposed that enables not only the customer but also a third-party verifier to check remote data integrity. This PDI scheme is provably secure and efficient. Compared to the best-known prior art, our experiments under defined conditions show that our PDI scheme works 50 times faster in fingerprinting the data, and the resulting fingerprints are 30 times smaller in size. [ABSTRACT FROM AUTHOR]

Multi-Identity Single-Key Decryption (MISKD) is an Identity-Based Encryption (IBE) system where a private decryption key can map multiple public keys (identities). More exactly, in MISKD, a single private key can be used to decrypt multiple ciphertexts encrypted with different public keys associated to the private key. MISKD is a variant of IBE and offers convenience to users who have to manage many private keys in a standard IBE. The notion of MISKD was recently introduced by Guo, Mu and Chen in Pairing 2007. They proposed a concrete MISKD scheme and proved its security based on the Bilinear Strong Diffie-Hellman problem (q-BSDH) in random oracle model. In this paper, we present a novel MISKD scheme that is provably secure in the selective-ID model based on the Decisional Bilinear Diffie-Hellman (DBDH) assumption. Our scheme is more efficient in decryption. [ABSTRACT FROM AUTHOR]