121,561 research outputs found
Consensus from Signatures of Work
Assuming the existence of a public-key infrastructure (PKI), digital signatures are a fundamental building block in the design of
secure consensus protocols
with optimal resilience.
More recently, with the advent of blockchain
protocols like Bitcoin, consensus has been considered in the ``permissionless\u27\u27
setting where no authentication or even point-to-point communication is available.
Yet, despite some positive preliminary
results, there has been no attempt to formalize a
building block that is sufficient for designing consensus protocols in this setting.
In this work we fill this void by putting forth a formalization of
such a primitive, which we call {\em signatures of work} (SoW). Distinctive features of our new notion are a lower bound on the number of steps required to produce a signature;
fast verification; {\em moderate unforgeability}---producing a sequence of SoWs, for chosen messages, does not provide an advantage to an adversary in terms of running time; and signing time independence---most relevant in concurrent multi-party applications, as we show.
Armed with SoW, we then present a new permissionless consensus protocol which is secure
assuming an honest majority of computational power,
thus providing
a blockchain counterpart to the classical Dolev-Strong consensus protocol.
The protocol is built on top of a SoW-based blockchain and standard properties of the underlying hash function,
thus improving on the only
known provably secure consensus protocol in this setting, which
relies on the random-oracle model in a fundamental way
Beating the fault-tolerance bound and security loopholes for Byzantine agreement with a quantum solution
Byzantine agreement, the underlying core of blockchain, aims to make every
node in a decentralized network reach consensus. Classical Byzantine agreements
unavoidably face two major problems. One is fault-tolerance bound, which
means that the system to tolerate malicious players requires at least
players. The other is the security loopholes from its classical
cryptography methods. Here, we propose a strict quantum Byzantine agreement
with unconditional security to break this bound with nearly fault
tolerance due to multiparty correlation provided by quantum digital signatures.
Our work strictly obeys the original Byzantine conditions and can be extended
to any number of players without requirements for multiparticle entanglement.
We experimentally demonstrate three-party and five-party quantum consensus for
a digital ledger. Our work indicates the quantum advantage in terms of
consensus problems and suggests an important avenue for quantum blockchain and
quantum consensus networks.Comment: 22 pages, 10 figures. All comments are welcome
Consensus Analysis of Whole Transcriptome Profiles from Two Breast Cancer Patient Cohorts Reveals Long Non-Coding RNAs Associated with Intrinsic Subtype and the Tumour Microenvironment.
Long non-coding RNAs (lncRNAs) are emerging as crucial regulators of cellular processes and diseases such as cancer; however, their functions remain poorly characterised. Several studies have demonstrated that lncRNAs are typically disease and tumour subtype specific, particularly in breast cancer where lncRNA expression alone is sufficient to discriminate samples based on hormone status and molecular intrinsic subtype. However, little attempt has been made to assess the reproducibility of lncRNA signatures across more than one dataset. In this work, we derive consensus lncRNA signatures indicative of breast cancer subtype based on two clinical RNA-Seq datasets: the Utah Breast Cancer Study and The Cancer Genome Atlas, through integration of differential expression and hypothesis-free clustering analyses. The most consistent signature is associated with breast cancers of the basal-like subtype, leading us to generate a putative set of six lncRNA basal-like breast cancer markers, at least two of which may have a role in cis-regulation of known poor prognosis markers. Through in silico functional characterization of individual signatures and integration of expression data from pre-clinical cancer models, we discover that discordance between signatures derived from different clinical cohorts can arise from the strong influence of non-cancerous cells in tumour samples. As a consequence, we identify nine lncRNAs putatively associated with breast cancer associated fibroblasts, or the immune response. Overall, our study establishes the confounding effects of tumour purity on lncRNA signature derivation, and generates several novel hypotheses on the role of lncRNAs in basal-like breast cancers and the tumour microenvironment
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