3,612 research outputs found
Approximate Quantum Error-Correcting Codes and Secret Sharing Schemes
It is a standard result in the theory of quantum error-correcting codes that
no code of length n can fix more than n/4 arbitrary errors, regardless of the
dimension of the coding and encoded Hilbert spaces. However, this bound only
applies to codes which recover the message exactly. Naively, one might expect
that correcting errors to very high fidelity would only allow small violations
of this bound. This intuition is incorrect: in this paper we describe quantum
error-correcting codes capable of correcting up to (n-1)/2 arbitrary errors
with fidelity exponentially close to 1, at the price of increasing the size of
the registers (i.e., the coding alphabet). This demonstrates a sharp
distinction between exact and approximate quantum error correction. The codes
have the property that any components reveal no information about the
message, and so they can also be viewed as error-tolerant secret sharing
schemes.
The construction has several interesting implications for cryptography and
quantum information theory. First, it suggests that secret sharing is a better
classical analogue to quantum error correction than is classical error
correction. Second, it highlights an error in a purported proof that verifiable
quantum secret sharing (VQSS) is impossible when the number of cheaters t is
n/4. More generally, the construction illustrates a difference between exact
and approximate requirements in quantum cryptography and (yet again) the
delicacy of security proofs and impossibility results in the quantum model.Comment: 14 pages, no figure
ARPA Whitepaper
We propose a secure computation solution for blockchain networks. The
correctness of computation is verifiable even under malicious majority
condition using information-theoretic Message Authentication Code (MAC), and
the privacy is preserved using Secret-Sharing. With state-of-the-art multiparty
computation protocol and a layer2 solution, our privacy-preserving computation
guarantees data security on blockchain, cryptographically, while reducing the
heavy-lifting computation job to a few nodes. This breakthrough has several
implications on the future of decentralized networks. First, secure computation
can be used to support Private Smart Contracts, where consensus is reached
without exposing the information in the public contract. Second, it enables
data to be shared and used in trustless network, without disclosing the raw
data during data-at-use, where data ownership and data usage is safely
separated. Last but not least, computation and verification processes are
separated, which can be perceived as computational sharding, this effectively
makes the transaction processing speed linear to the number of participating
nodes. Our objective is to deploy our secure computation network as an layer2
solution to any blockchain system. Smart Contracts\cite{smartcontract} will be
used as bridge to link the blockchain and computation networks. Additionally,
they will be used as verifier to ensure that outsourced computation is
completed correctly. In order to achieve this, we first develop a general MPC
network with advanced features, such as: 1) Secure Computation, 2) Off-chain
Computation, 3) Verifiable Computation, and 4)Support dApps' needs like
privacy-preserving data exchange
Ideal Tightly Couple (t,m,n) Secret Sharing
As a fundamental cryptographic tool, (t,n)-threshold secret sharing
((t,n)-SS) divides a secret among n shareholders and requires at least t,
(t<=n), of them to reconstruct the secret. Ideal (t,n)-SSs are most desirable
in security and efficiency among basic (t,n)-SSs. However, an adversary, even
without any valid share, may mount Illegal Participant (IP) attack or
t/2-Private Channel Cracking (t/2-PCC) attack to obtain the secret in most
(t,n)-SSs.To secure ideal (t,n)-SSs against the 2 attacks, 1) the paper
introduces the notion of Ideal Tightly cOupled (t,m,n) Secret Sharing (or
(t,m,n)-ITOSS ) to thwart IP attack without Verifiable SS; (t,m,n)-ITOSS binds
all m, (m>=t), participants into a tightly coupled group and requires all
participants to be legal shareholders before recovering the secret. 2) As an
example, the paper presents a polynomial-based (t,m,n)-ITOSS scheme, in which
the proposed k-round Random Number Selection (RNS) guarantees that adversaries
have to crack at least symmetrical private channels among participants before
obtaining the secret. Therefore, k-round RNS enhances the robustness of
(t,m,n)-ITOSS against t/2-PCC attack to the utmost. 3) The paper finally
presents a generalized method of converting an ideal (t,n)-SS into a
(t,m,n)-ITOSS, which helps an ideal (t,n)-SS substantially improve the
robustness against the above 2 attacks
Frictionless Authentication Systems: Emerging Trends, Research Challenges and Opportunities
Authentication and authorization are critical security layers to protect a
wide range of online systems, services and content. However, the increased
prevalence of wearable and mobile devices, the expectations of a frictionless
experience and the diverse user environments will challenge the way users are
authenticated. Consumers demand secure and privacy-aware access from any
device, whenever and wherever they are, without any obstacles. This paper
reviews emerging trends and challenges with frictionless authentication systems
and identifies opportunities for further research related to the enrollment of
users, the usability of authentication schemes, as well as security and privacy
trade-offs of mobile and wearable continuous authentication systems.Comment: published at the 11th International Conference on Emerging Security
Information, Systems and Technologies (SECURWARE 2017
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