75 research outputs found
Optimal Locally Repairable and Secure Codes for Distributed Storage Systems
This paper aims to go beyond resilience into the study of security and
local-repairability for distributed storage systems (DSS). Security and
local-repairability are both important as features of an efficient storage
system, and this paper aims to understand the trade-offs between resilience,
security, and local-repairability in these systems. In particular, this paper
first investigates security in the presence of colluding eavesdroppers, where
eavesdroppers are assumed to work together in decoding stored information.
Second, the paper focuses on coding schemes that enable optimal local repairs.
It further brings these two concepts together, to develop locally repairable
coding schemes for DSS that are secure against eavesdroppers.
The main results of this paper include: a. An improved bound on the secrecy
capacity for minimum storage regenerating codes, b. secure coding schemes that
achieve the bound for some special cases, c. a new bound on minimum distance
for locally repairable codes, d. code construction for locally repairable codes
that attain the minimum distance bound, and e. repair-bandwidth-efficient
locally repairable codes with and without security constraints.Comment: Submitted to IEEE Transactions on Information Theor
Gabidulin Codes with Support Constrained Generator Matrices
Gabidulin codes are the first general construction of linear codes that are
maximum rank distant (MRD). They have found applications in linear network
coding, for example, when the transmitter and receiver are oblivious to the
inner workings and topology of the network (the so-called incoherent regime).
The reason is that Gabidulin codes can be used to map information to linear
subspaces, which in the absence of errors cannot be altered by linear
operations, and in the presence of errors can be corrected if the subspace is
perturbed by a small rank. Furthermore, in distributed coding and distributed
systems, one is led to the design of error correcting codes whose generator
matrix must satisfy a given support constraint. In this paper, we give
necessary and sufficient conditions on the support of the generator matrix that
guarantees the existence of Gabidulin codes and general MRD codes. When the
rate of the code is not very high, this is achieved with the same field size
necessary for Gabidulin codes with no support constraint. When these conditions
are not satisfied, we characterize the largest possible rank distance under the
support constraints and show that they can be achieved by subcodes of Gabidulin
codes. The necessary and sufficient conditions are identical to those that
appear for MDS codes which were recently proven by Yildiz et al. and Lovett in
the context of settling the GM-MDS conjecture
Secure Cooperative Regenerating Codes for Distributed Storage Systems
Regenerating codes enable trading off repair bandwidth for storage in
distributed storage systems (DSS). Due to their distributed nature, these
systems are intrinsically susceptible to attacks, and they may also be subject
to multiple simultaneous node failures. Cooperative regenerating codes allow
bandwidth efficient repair of multiple simultaneous node failures. This paper
analyzes storage systems that employ cooperative regenerating codes that are
robust to (passive) eavesdroppers. The analysis is divided into two parts,
studying both minimum bandwidth and minimum storage cooperative regenerating
scenarios. First, the secrecy capacity for minimum bandwidth cooperative
regenerating codes is characterized. Second, for minimum storage cooperative
regenerating codes, a secure file size upper bound and achievability results
are provided. These results establish the secrecy capacity for the minimum
storage scenario for certain special cases. In all scenarios, the achievability
results correspond to exact repair, and secure file size upper bounds are
obtained using min-cut analyses over a suitable secrecy graph representation of
DSS. The main achievability argument is based on an appropriate pre-coding of
the data to eliminate the information leakage to the eavesdropper
Coding with Constraints: Minimum Distance Bounds and Systematic Constructions
We examine an error-correcting coding framework in which each coded symbol is
constrained to be a function of a fixed subset of the message symbols. With an
eye toward distributed storage applications, we seek to design systematic codes
with good minimum distance that can be decoded efficiently. On this note, we
provide theoretical bounds on the minimum distance of such a code based on the
coded symbol constraints. We refine these bounds in the case where we demand a
systematic linear code. Finally, we provide conditions under which each of
these bounds can be achieved by choosing our code to be a subcode of a
Reed-Solomon code, allowing for efficient decoding. This problem has been
considered in multisource multicast network error correction. The problem setup
is also reminiscent of locally repairable codes.Comment: Submitted to ISIT 201
New Parameters of Linear Codes Expressing Security Performance of Universal Secure Network Coding
The universal secure network coding presented by Silva et al. realizes secure
and reliable transmission of a secret message over any underlying network code,
by using maximum rank distance codes. Inspired by their result, this paper
considers the secure network coding based on arbitrary linear codes, and
investigates its security performance and error correction capability that are
guaranteed independently of the underlying network code. The security
performance and error correction capability are said to be universal when they
are independent of underlying network codes. This paper introduces new code
parameters, the relative dimension/intersection profile (RDIP) and the relative
generalized rank weight (RGRW) of linear codes. We reveal that the universal
security performance and universal error correction capability of secure
network coding are expressed in terms of the RDIP and RGRW of linear codes. The
security and error correction of existing schemes are also analyzed as
applications of the RDIP and RGRW.Comment: IEEEtran.cls, 8 pages, no figure. To appear in Proc. 50th Annual
Allerton Conference on Communication, Control, and Computing (Allerton 2012).
Version 2 added an exact expression of the universal error correction
capability in terms of the relative generalized rank weigh
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