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27
Visual Cryptography for General Access Structures
, 1996
"... A visual cryptography scheme for a set P of n participants is a method to encode a secret image SI into n shadow images called shares, where each participant in P receives one share. Certain qualified subsets of participants can "visually" recover the secret image, but other, forbidden, se ..."
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Cited by 103 (9 self)
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A visual cryptography scheme for a set P of n participants is a method to encode a secret image SI into n shadow images called shares, where each participant in P receives one share. Certain qualified subsets of participants can "visually" recover the secret image, but other, forbidden, sets of participants have no information (in an informationtheoretic sense) on SI . A "visual" recovery for a set X ` P consists of xeroxing the shares given to the participants in X onto transparencies, and then stacking them. The participants in a qualified set X will be able to see the secret image without any knowledge of Cryptography and without performing any cryptographic computation. In this paper we propose two techniques to construct visual cryptography schemes for general access structures. We analyze the structure of visual cryptography schemes and we prove bounds on the size of the shares distributed to the participants in the scheme. We provide a novel technique to realize k out of n thre...
Combinatorial properties and constructions of traceability schemes and frameproof codes
 SIAM Journal on Discrete Mathematics
, 1998
"... In this paper, weinvestigate combinatorial properties and constructions of two recent topics of cryptographic interest, namely frameproof codes for digital ngerprinting, and traceability schemes for broadcast encryption. We rstgive combinatorial descriptions of these two objects in terms of set syst ..."
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Cited by 76 (6 self)
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In this paper, weinvestigate combinatorial properties and constructions of two recent topics of cryptographic interest, namely frameproof codes for digital ngerprinting, and traceability schemes for broadcast encryption. We rstgive combinatorial descriptions of these two objects in terms of set systems, and also discuss the Hamming distance of frameproof codes when viewed as errorcorrecting codes. From these descriptions, it is seen that existence of a ctraceability scheme implies the existence of a cframeproof code. We then give several constructions of frameproof codes and traceability schemes by using combinatorial structures such as tdesigns, packing designs, errorcorrecting codes and perfect hash families. We also investigate embeddings of frameproof codes and traceability schemes, which allow agiven scheme to be expanded at a later date to accommodate more users. Finally, we look brie y at bounds which establish necessary conditions for existence of these structures. 1
Combinatorial Properties of Frameproof and Traceability Codes
 IEEE Transactions on Information Theory
, 2000
"... In order to protect copyrighted material, codes may be embedded in the content or codes may be associated with the keys used to recover the content. Codes can oer protection by providing some form of traceability for pirated data. Several researchers have studied dierent notions of traceability a ..."
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Cited by 74 (10 self)
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In order to protect copyrighted material, codes may be embedded in the content or codes may be associated with the keys used to recover the content. Codes can oer protection by providing some form of traceability for pirated data. Several researchers have studied dierent notions of traceability and related concepts in recent years. \Strong" versions of traceability allow at least one member of a coalition that constructs a \pirate decoder" to be traced. Weaker versions of this concept ensure that no coalition can \frame" a disjoint user or group of users. All these concepts can be formulated as codes having certain combinatorial properties. In this paper, we study the relationships between the various notions, and we discuss equivalent formulations using structures such as perfect hash families. We use methods from combinatorics and coding theory to provide bounds (necessary conditions) and constructions (sucient conditions) for the objects of interest. 1 Introduction In...
Secure Frameproof Codes, Key Distribution Patterns, Group Testing Algorithms and Related Structures
 Journal of Statistical Planning and Inference
, 1997
"... Frameproof codes were introduced by Boneh and Shaw as a method of "digital fingerprinting" which prevents a coalition of a specified size c from framing a user not in the coalition. Stinson and Wei then gave a combinatorial formulation of the problem in terms of certain types of extremal s ..."
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Cited by 64 (13 self)
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Frameproof codes were introduced by Boneh and Shaw as a method of "digital fingerprinting" which prevents a coalition of a specified size c from framing a user not in the coalition. Stinson and Wei then gave a combinatorial formulation of the problem in terms of certain types of extremal set sytems. In this paper, we study frameproof codes that provide a certain (weak) form of traceability. We extend our combinatorial formulation to address this stronger requirement, and show that the problem is solved by using (i; j)separating systems, as defined by Friedman, Graham and Ullman. Using constructions based on perfect hash families, we give the first efficient explicit constructions for these objects for general values of i and j. We also review nonconstructive existence results that are based on probabilistic arguments. Then we look at two other, related concepts, namely key distribution patterns and nonadaptive group testing algorithms. We again approach these problems from the point...
On Some Methods for Unconditionally Secure Key Distribution and Broadcast Encryption
 Designs, Codes and Cryptography
, 1996
"... This paper provides an exposition of methods by which a trusted authority can distribute keys and/or broadcast a message over a network, so that each member of a privileged subset of users can compute a specified key or decrypt the broadcast message. Moreover, this is done in such a way that no coal ..."
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Cited by 62 (8 self)
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This paper provides an exposition of methods by which a trusted authority can distribute keys and/or broadcast a message over a network, so that each member of a privileged subset of users can compute a specified key or decrypt the broadcast message. Moreover, this is done in such a way that no coalition is able to recover any information on a key or broadcast message they are not supposed to know. The problems are studied using the tools of information theory, so the security provided is unconditional (i.e., not based on any computational assumption). We begin by surveying some useful schemes schemes for key distribution that have been presented in the literature, giving background and examples (but not too many proofs). In particular, we look more closely at the attractive concept of key distribution patterns, and present a new method for making these schemes more efficient through the use of resilient functions. Then we present a general approach to the construction of broadcast sch...
Applications of Combinatorial Designs to Communications, Cryptography, and Networking
, 1999
"... ... In this paper, we focus on another collection of recent applications in the general area of communications, including cryptography and networking. Applications have been chosen to represent those in which design theory plays a useful, and sometimes central, role. Moreover, applications have been ..."
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Cited by 37 (3 self)
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... In this paper, we focus on another collection of recent applications in the general area of communications, including cryptography and networking. Applications have been chosen to represent those in which design theory plays a useful, and sometimes central, role. Moreover, applications have been chosen to reflect in addition the genesis of new and interesting problems in design theory in order to treat the practical concerns. Of many candidates, thirteen applications areas have been included. They are as follows:
Combinatorial aspects of covering arrays
 Le Matematiche (Catania
"... Covering arrays generalize orthogonal arrays by requiring that ttuples be covered, but not requiring that the appearance of ttuples be balanced. Their uses in screening experiments has found application in software testing, hardware testing, and a variety of fields in which interactions among fact ..."
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Cited by 34 (8 self)
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Covering arrays generalize orthogonal arrays by requiring that ttuples be covered, but not requiring that the appearance of ttuples be balanced. Their uses in screening experiments has found application in software testing, hardware testing, and a variety of fields in which interactions among factors are to be identified. Here a combinatorial view of covering arrays is adopted, encompassing basic bounds, direct constructions, recursive constructions, algorithmic methods, and applications.
New Constructions for Perfect Hash Families and Related Structures using Combinatorial Designs
 J. COMBIN. DESIGNS
, 1999
"... In this paper, we consider explicit constructions of perfect hash families using combinatorial methods. We provide several direct constructions from combinatorial structures related to orthogonal arrays. We also simplify and generalize a recursive construction due to Atici, Magliversas, Stinson and ..."
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Cited by 23 (7 self)
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In this paper, we consider explicit constructions of perfect hash families using combinatorial methods. We provide several direct constructions from combinatorial structures related to orthogonal arrays. We also simplify and generalize a recursive construction due to Atici, Magliversas, Stinson and Wei [3]. Using similar methods, we also obtain efficient constructions for separating hash families which result in improved existence results for structures such as separating systems, key distribution patterns, group testing algorithms, coverfree families and secure frameproof codes.
Constructions and Bounds for Visual Cryptography
 of &quot;Lecture Notes in Computer Science
, 1996
"... . A visual cryptography scheme for a set P of n participants is a method to encode a secret image SI into n images in such a way that any participant in P receives one image and only qualified subsets of participants can "visually" recover the secret image, but nonqualified sets of partic ..."
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Cited by 19 (7 self)
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. A visual cryptography scheme for a set P of n participants is a method to encode a secret image SI into n images in such a way that any participant in P receives one image and only qualified subsets of participants can "visually" recover the secret image, but nonqualified sets of participants have no information, in an information theoretical sense, on SI. A "visual" recover for a set X ` P consists of stacking together the images associated to participants in X. The participants in a qualified set X will be able to see the secret image without any knowledge of cryptography and without performing any cryptographic computation. In this paper we propose two techniques to construct visual cryptography schemes for any access structure. We analyze the structure of visual cryptography schemes and we prove bounds on the size of the image distributed to the participants in the scheme. We provide a novel technique to realize k out of n visual cryptography schemes. Finally, we consider graph...
Rouxtype constructions for covering arrays of strengths three and four
, 2006
"... A covering array CA(N; t; k; v) is an N k array such that every N t subarray contains all ttuples from v symbols at least once, where t is the strength of the array. Covering arrays are used to generate software test suites to cover all tsets of component interactions. Recursive constructions f ..."
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Cited by 10 (3 self)
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A covering array CA(N; t; k; v) is an N k array such that every N t subarray contains all ttuples from v symbols at least once, where t is the strength of the array. Covering arrays are used to generate software test suites to cover all tsets of component interactions. Recursive constructions for covering arrays of strengths 3 and 4 are developed, generalizing many "Rouxtype" constructions. A numerical comparison with current construction techniques is given through existence tables for covering arrays.