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Collusion resistant broadcast encryption with short ciphertexts and private keys
"... We describe two new public key broadcast encryption systems for stateless receivers. Both systems are fully secure against any number of colluders. In our first construction both ciphertexts and private keys are of constant size (only two group elements), for any subset of receivers. The public ke ..."
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Cited by 121 (13 self)
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We describe two new public key broadcast encryption systems for stateless receivers. Both systems are fully secure against any number of colluders. In our first construction both ciphertexts and private keys are of constant size (only two group elements), for any subset of receivers. The public key size in this system is linear in the total number of receivers. Our second system is a generalization of the first that provides a tradeoff between ciphertext size and public key size. For example, we achieve a collusion resistant broadcast system for n users where both ciphertexts and public keys are of size O (√n) for any subset of receivers. We discuss several applications of these systems.
Searchable encryption revisited: Consistency properties, relation to anonymous ibe, and extensions. Full version of current paper. Available at IACR Cryptology ePrint Archive, http://eprint.iacr.org
"... Abstract. We identify and fill some gaps with regard to consistency (the extent to which false positives are produced) for publickey encryption with keyword search (PEKS). We define computational and statistical relaxations of the existing notion of perfect consistency, show that the scheme of [7] ..."
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Cited by 81 (3 self)
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Abstract. We identify and fill some gaps with regard to consistency (the extent to which false positives are produced) for publickey encryption with keyword search (PEKS). We define computational and statistical relaxations of the existing notion of perfect consistency, show that the scheme of [7] is computationally consistent, and provide a new scheme that is statistically consistent. We also provide a transform of an anonymous IBE scheme to a secure PEKS scheme that, unlike the previous one, guarantees consistency. Finally we suggest three extensions of the basic notions considered here, namely anonymous HIBE, publickey encryption with temporary keyword search, and identitybased encryption
Pairingbased Cryptography at High Security Levels
 Proceedings of Cryptography and Coding 2005, volume 3796 of LNCS
, 2005
"... Abstract. In recent years cryptographic protocols based on the Weil and Tate pairings on elliptic curves have attracted much attention. A notable success in this area was the elegant solution by Boneh and Franklin [7] of the problem of efficient identitybased encryption. At the same time, the secur ..."
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Cited by 77 (2 self)
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Abstract. In recent years cryptographic protocols based on the Weil and Tate pairings on elliptic curves have attracted much attention. A notable success in this area was the elegant solution by Boneh and Franklin [7] of the problem of efficient identitybased encryption. At the same time, the security standards for public key cryptosystems are expected to increase, so that in the future they will be capable of providing security equivalent to 128, 192, or 256bit AES keys. In this paper we examine the implications of heightened security needs for pairingbased cryptosystems. We first describe three different reasons why highsecurity users might have concerns about the longterm viability of these systems. However, in our view none of the risks inherent in pairingbased systems are sufficiently serious to warrant pulling them from the shelves. We next discuss two families of elliptic curves E for use in pairingbased cryptosystems. The first has the property that the pairing takes values in the prime field Fp over which the curve is defined; the second family consists of supersingular curves with embedding degree k = 2. Finally, we examine the efficiency of the Weil pairing as opposed to the Tate pairing and compare a range of choices of embedding degree k, including k = 1 and k = 24. Let E be the elliptic curve 1.
Predicate Encryption Supporting Disjunctions, Polynomial Equations, and Inner Products
"... Abstract. Predicate encryption is a new paradigm generalizing, among other things, identitybased encryption. In a predicate encryption scheme, secret keys correspond to predicates and ciphertexts are associated with attributes; the secret key SKf corresponding to a predicate f can be used to decryp ..."
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Cited by 77 (15 self)
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Abstract. Predicate encryption is a new paradigm generalizing, among other things, identitybased encryption. In a predicate encryption scheme, secret keys correspond to predicates and ciphertexts are associated with attributes; the secret key SKf corresponding to a predicate f can be used to decrypt a ciphertext associated with attribute I if and only if f(I) = 1. Constructions of such schemes are currently known for relatively few classes of predicates. We construct such a scheme for predicates corresponding to the evaluation of inner products over ZN (for some large integer N). This, in turn, enables constructions in which predicates correspond to the evaluation of disjunctions, polynomials, CNF/DNF formulae, or threshold predicates (among others). Besides serving as a significant step forward in the theory of predicate encryption, our results lead to a number of applications that are interesting in their own right. 1
Direct Chosen Ciphertext Security from IdentityBased Techniques
 In ACM Conference on Computer and Communications Security
, 2005
"... We describe a new encryption technique that is secure in the standard model against adaptive chosen ciphertext (CCA2) attacks. We base our method on two very e#cient IdentityBased Encryption (IBE) schemes without random oracles due to Boneh and Boyen, and Waters. ..."
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Cited by 72 (7 self)
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We describe a new encryption technique that is secure in the standard model against adaptive chosen ciphertext (CCA2) attacks. We base our method on two very e#cient IdentityBased Encryption (IBE) schemes without random oracles due to Boneh and Boyen, and Waters.
Fully Secure Functional Encryption: AttributeBased Encryption and (Hierarchical) Inner Product Encryption
"... In this paper, we present two fully secure functional encryption schemes. Our first result is a fully secure attributebased encryption (ABE) scheme. Previous constructions of ABE were only proven to be selectively secure. We achieve full security by adapting the dual system encryption methodology r ..."
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Cited by 53 (13 self)
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In this paper, we present two fully secure functional encryption schemes. Our first result is a fully secure attributebased encryption (ABE) scheme. Previous constructions of ABE were only proven to be selectively secure. We achieve full security by adapting the dual system encryption methodology recently introduced by Waters and previously leveraged to obtain fully secure IBE and HIBE systems. The primary challenge in applying dual system encryption to ABE is the richer structure of keys and ciphertexts. In an IBE or HIBE system, keys and ciphertexts are both associated with the same type of simple object: identities. In an ABE system, keys and ciphertexts are associated with more complex objects: attributes and access formulas. We use a novel informationtheoretic argument to adapt the dual system encryption methodology to the more complicated structure of ABE systems. We construct our system in composite order bilinear groups, where the order is a product of three primes. We prove the security of our system from three static assumptions. Our ABE scheme supports arbitrary monotone access formulas. Our second result is a fully secure (attributehiding) predicate encryption (PE) scheme
Multidimension range query over encrypted data
 In IEEE Symposium on Security and Privacy
, 2007
"... encryption We design an encryption scheme called Multidimensional Range Query over Encrypted Data (MRQED), to address the privacy concerns related to the sharing of network audit logs and various other applications. Our scheme allows a network gateway to encrypt summaries of network flows before su ..."
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Cited by 44 (3 self)
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encryption We design an encryption scheme called Multidimensional Range Query over Encrypted Data (MRQED), to address the privacy concerns related to the sharing of network audit logs and various other applications. Our scheme allows a network gateway to encrypt summaries of network flows before submitting them to an untrusted repository. When network intrusions are suspected, an authority can release a key to an auditor, allowing the auditor to decrypt flows whose attributes (e.g., source and destination addresses, port numbers, etc.) fall within specific ranges. However, the privacy of all irrelevant flows are still preserved. We formally define the security for MRQED and prove the security of our construction under the decision bilinear DiffieHellman and decision linear assumptions in certain bilinear groups. We study the practical performance of our construction in the context of network audit logs. Apart from network audit logs, our scheme also has interesting applications for financial audit logs, medical privacy, untrusted remote storage, etc. In particular, we show that MRQED implies a solution to its dual problem, which enables investors to trade stocks through a broker in a privacypreserving manner. 1
Appendonly signatures
 in International Colloquium on Automata, Languages and Programming
, 2005
"... Abstract. The strongest standard security notion for digital signature schemes is unforgeability under chosen message attacks. In practice, however, this notion can be insufficient due to “sidechannel attacks ” which exploit leakage of information about the secret internal state. In this work we pu ..."
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Cited by 35 (10 self)
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Abstract. The strongest standard security notion for digital signature schemes is unforgeability under chosen message attacks. In practice, however, this notion can be insufficient due to “sidechannel attacks ” which exploit leakage of information about the secret internal state. In this work we put forward the notion of “leakageresilient signatures, ” which strengthens the standard security notion by giving the adversary the additional power to learn a bounded amount of arbitrary information about the secret state that was accessed during every signature generation. This notion naturally implies security against all sidechannel attacks as long as the amount of information leaked on each invocation is bounded and “only computation leaks information.” The main result of this paper is a construction which gives a (treebased, stateful) leakageresilient signature scheme based on any 3time signature scheme. The amount of information that our scheme can safely leak per signature generation is 1/3 of the information the underlying 3time signature scheme can leak in total. Signature schemes that remain secure even if a bounded total amount of information is leaked were recently constructed, hence instantiating our construction with these schemes gives the first constructions of provably secure leakageresilient signature schemes. The above construction assumes that the signing algorithm can sample truly random bits, and thus an implementation would need some special hardware (randomness gates). Simply generating this randomness using a leakageresilient streamcipher will in general not work. Our second contribution is a sound general principle to replace uniform random bits in any leakageresilient construction with pseudorandom ones: run two leakageresilient streamciphers (with independent keys) in parallel and then apply a twosource extractor to their outputs. 1
CiphertextPolicy AttributeBased Encryption: An Expressive, Efficient, and Provably Secure Realization
"... We present new techniques for realizing CiphertextPolicy Attribute Encryption (CPABE) under concrete and noninteractive cryptographic assumptions. Our solutions allow any encryptor to specify access control in terms of an LSSS matrix, M, over the attributes in the system. We present three differen ..."
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Cited by 34 (6 self)
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We present new techniques for realizing CiphertextPolicy Attribute Encryption (CPABE) under concrete and noninteractive cryptographic assumptions. Our solutions allow any encryptor to specify access control in terms of an LSSS matrix, M, over the attributes in the system. We present three different constructions that allow different tradeoffs between the systems efficiency and the complexity of the assumptions used. All three constructions use a common methodology of “directly ” solving the CPABE problem that enable us to get much better efficiency than prior approaches. 1
New Techniques for Dual System Encryption and Fully Secure HIBE with Short Ciphertexts
"... We construct a fully secure HIBE scheme with short ciphertexts. The previous construction of Boneh, Boyen, and Goh was only proven to be secure in the selective model, under a nonstatic assumption which depended on the depth of the hierarchy. To obtain full security, we apply the dual system encryp ..."
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Cited by 30 (10 self)
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We construct a fully secure HIBE scheme with short ciphertexts. The previous construction of Boneh, Boyen, and Goh was only proven to be secure in the selective model, under a nonstatic assumption which depended on the depth of the hierarchy. To obtain full security, we apply the dual system encryption concept recently introduced by Waters. A straightforward application of this technique is insufficient to achieve short ciphertexts, since the original instantiation of the technique includes tags that do not compress. To overcome this challenge, we design a new method for realizing dual system encryption. We provide a system in composite order groups (of three primes) and prove the security of our scheme under three static assumptions.