10,154 research outputs found
Can NSEC5 be practical for DNSSEC deployments?
NSEC5 is proposed modification to DNSSEC that simultaneously guarantees two security properties: (1) privacy against offline zone enumeration, and (2) integrity of zone contents, even if an adversary compromises the authoritative nameserver responsible for responding to DNS queries for the zone. This paper redesigns NSEC5 to make it both practical and performant. Our NSEC5 redesign features a new fast verifiable random function (VRF) based on elliptic curve cryptography (ECC), along with a cryptographic proof of its security. This VRF is also of independent interest, as it is being standardized by the IETF and being used by several other projects. We show how to integrate NSEC5 using our ECC-based VRF into the DNSSEC protocol, leveraging precomputation to improve performance and DNS protocol-level optimizations to shorten responses. Next, we present the first full-fledged implementation of NSEC5—extending widely-used DNS software to present a nameserver and recursive resolver that support NSEC5—and evaluate their performance under aggressive DNS query loads. Our performance results
indicate that our redesigned NSEC5 can be viable even for high-throughput scenarioshttps://eprint.iacr.org/2017/099.pdfFirst author draf
Computational and Energy Costs of Cryptographic Algorithms on Handheld Devices
Networks are evolving toward a ubiquitous model in which heterogeneous
devices are interconnected. Cryptographic algorithms are required for developing security
solutions that protect network activity. However, the computational and energy limitations
of network devices jeopardize the actual implementation of such mechanisms. In this
paper, we perform a wide analysis on the expenses of launching symmetric and asymmetric
cryptographic algorithms, hash chain functions, elliptic curves cryptography and pairing
based cryptography on personal agendas, and compare them with the costs of basic operating
system functions. Results show that although cryptographic power costs are high and such
operations shall be restricted in time, they are not the main limiting factor of the autonomy
of a device
Pendekatan konstruktif dalam inovasi pengajaran dan pembelajaran Bahasa Melayu di Kolej Vokasional
Pendekatan konstruktif adalah pendekatan pengajaran dan pembelajaran yang
berpusatkan pelajar manakala inovasi pengajaran pula dikaitkan dengan kaedah
pengajaran yang terbaru demi mengukuhkan pemahaman pelajar. Pembelajaran
berasaskan pendekatan konstruktif merupakan elemen yang penting dan perlu
difahami oleh guru-guru bagi memantapkan proses pengajaran dan pembelajaran
sesuai dengan peredaran masa dan menjayakan proses tranformasi pendidikan
negara. Objektif kajian ini dijalankan untuk mengenal pasti pemahaman guru-guru
bahasa Melayu berkaitan inovasi, mengenal pasti perbezaan yang wujud antara guru
lelaki dan guru perempuan dalam mengamalkan inovasi, pengkaji juga melihat
adakah wujud perbezaan antara guru baru dan guru yang sudah berpengalaman
dalam aspek mengaplikasikan inovasi serta mengenal pasti kekangan-kekangan yang
dialami oleh para guru untuk mengaplikasikan inovasi di sekolah. Seramai 63 orang
guru bahasa Melayu dari lapan buah kolej vokasional telah dipilih sebagai responden
dalam kajian ini. Data dianalisis menggunakan perisian Winsteps 3.69.1.11 dengan
pendekatan Model Pengukuran Rasch. Hasil analisis menunjukkan bahawa guru�guru bahasa Melayu memahami kepentingan inovasi dalam pengajaran dan
pembelajaran. Hasil kajian juga menunjukkan guru-guru perempuan lebih banyak
menerapkan unsur inovasi dalam pengajaran berbanding guru lelaki. Walaupun
begitu, aspek pengalaman tidak menunjukkan perbezaan dari segi pengamalan
inovasi sama ada guru baru ataupun guru yang sudah berpengalaman. Pengkaji juga
mengenal pasti beberapa kekangan yang dialami oleh guru-guru untuk mengamalkan
inovasi ini. Sebagai langkah untuk menangani masalah berkenaan, beberapa
cadangan telah dikemukakan oleh pengkaji bagi memastikan guru-guru dapat
merealisasikan proses pengajaran berkesan dengan penerapan inovasi mengikut
model pendekatan konstruktif. Pengkaji berharap, kajian ini dapat dijadikan sebagai
satu panduan kepada pelaksana kurikulum bagi memastikan budaya inovasi sentiasa
menjadi amalan dalam kalangan guru demi mengangkat profesionalisme guru di
Malaysia
On the efficiency of revocation in RSA-based anonymous systems
© 2016 IEEEThe problem of revocation in anonymous authentication systems is subtle and has motivated a lot of work. One of the preferable solutions consists in maintaining either a whitelist L-W of non-revoked users or a blacklist L-B of revoked users, and then requiring users to additionally prove, when authenticating themselves, that they are in L-W (membership proof) or that they are not in L-B (non-membership proof). Of course, these additional proofs must not break the anonymity properties of the system, so they must be zero-knowledge proofs, revealing nothing about the identity of the users. In this paper, we focus on the RSA-based setting, and we consider the case of non-membership proofs to blacklists L = L-B. The existing solutions for this setting rely on the use of universal dynamic accumulators; the underlying zero-knowledge proofs are bit complicated, and thus their efficiency; although being independent from the size of the blacklist L, seems to be improvable. Peng and Bao already tried to propose simpler and more efficient zero-knowledge proofs for this setting, but we prove in this paper that their protocol is not secure. We fix the problem by designing a new protocol, and formally proving its security properties. We then compare the efficiency of the new zero-knowledge non-membership protocol with that of the protocol, when they are integrated with anonymous authentication systems based on RSA (notably, the IBM product Idemix for anonymous credentials). We discuss for which values of the size k of the blacklist L, one protocol is preferable to the other one, and we propose different ways to combine and implement the two protocols.Postprint (author's final draft
A Touch of Evil: High-Assurance Cryptographic Hardware from Untrusted Components
The semiconductor industry is fully globalized and integrated circuits (ICs)
are commonly defined, designed and fabricated in different premises across the
world. This reduces production costs, but also exposes ICs to supply chain
attacks, where insiders introduce malicious circuitry into the final products.
Additionally, despite extensive post-fabrication testing, it is not uncommon
for ICs with subtle fabrication errors to make it into production systems.
While many systems may be able to tolerate a few byzantine components, this is
not the case for cryptographic hardware, storing and computing on confidential
data. For this reason, many error and backdoor detection techniques have been
proposed over the years. So far all attempts have been either quickly
circumvented, or come with unrealistically high manufacturing costs and
complexity.
This paper proposes Myst, a practical high-assurance architecture, that uses
commercial off-the-shelf (COTS) hardware, and provides strong security
guarantees, even in the presence of multiple malicious or faulty components.
The key idea is to combine protective-redundancy with modern threshold
cryptographic techniques to build a system tolerant to hardware trojans and
errors. To evaluate our design, we build a Hardware Security Module that
provides the highest level of assurance possible with COTS components.
Specifically, we employ more than a hundred COTS secure crypto-coprocessors,
verified to FIPS140-2 Level 4 tamper-resistance standards, and use them to
realize high-confidentiality random number generation, key derivation, public
key decryption and signing. Our experiments show a reasonable computational
overhead (less than 1% for both Decryption and Signing) and an exponential
increase in backdoor-tolerance as more ICs are added
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