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Security Arguments for Digital Signatures and Blind Signatures
 JOURNAL OF CRYPTOLOGY
, 2000
"... Since the appearance of publickey cryptography in the seminal DiffieHellman paper, many new schemes have been proposed and many have been broken. Thus, the ..."
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Cited by 374 (41 self)
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Since the appearance of publickey cryptography in the seminal DiffieHellman paper, many new schemes have been proposed and many have been broken. Thus, the
Evaluating 2dnf formulas on ciphertexts
 In proceedings of TCC ’05, LNCS series
, 2005
"... Abstract. Let ψ be a 2DNF formula on boolean variables x1,..., xn ∈ {0, 1}. We present a homomorphic public key encryption scheme that allows the public evaluation of ψ given an encryption of the variables x1,..., xn. In other words, given the encryption of the bits x1,..., xn, anyone can create th ..."
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Cited by 231 (7 self)
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Abstract. Let ψ be a 2DNF formula on boolean variables x1,..., xn ∈ {0, 1}. We present a homomorphic public key encryption scheme that allows the public evaluation of ψ given an encryption of the variables x1,..., xn. In other words, given the encryption of the bits x1,..., xn, anyone can create the encryption of ψ(x1,..., xn). More generally, we can evaluate quadratic multivariate polynomials on ciphertexts provided the resulting value falls within a small set. We present a number of applications of the system: 1. In a database of size n, the total communication in the basic step of the KushilevitzOstrovsky PIR protocol is reduced from √ n to 3 √ n. 2. An efficient election system based on homomorphic encryption where voters do not need to include noninteractive zero knowledge proofs that their ballots are valid. The election system is proved secure without random oracles but still efficient. 3. A protocol for universally verifiable computation. 1
A forwardsecure digital signature scheme
, 1999
"... Abstract. We describe a digital signature scheme in which the public key is fixed but the secret signing key is updated at regular intervals so as to provide a forward security property: compromise of the current secret key does not enable an adversary to forge signatures pertaining to the past. Thi ..."
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Cited by 208 (13 self)
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Abstract. We describe a digital signature scheme in which the public key is fixed but the secret signing key is updated at regular intervals so as to provide a forward security property: compromise of the current secret key does not enable an adversary to forge signatures pertaining to the past. This can be useful to mitigate the damage caused by key exposure without requiring distribution of keys. Our construction uses ideas from the FiatShamir and OngSchnorr identification and signature schemes, and is proven to be forward secure based on the hardness of factoring, in the random oracle model. The construction is also quite efficient. 1
Direct Anonymous Attestation
, 2004
"... This paper describes the direct anonymous attestation scheme (DAA). This scheme was adopted by the Trusted Computing Group as the method for remote authentication of a hardware module, called trusted platform module (TPM), while preserving the privacy of the user of the platform that contains the ..."
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Cited by 205 (21 self)
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This paper describes the direct anonymous attestation scheme (DAA). This scheme was adopted by the Trusted Computing Group as the method for remote authentication of a hardware module, called trusted platform module (TPM), while preserving the privacy of the user of the platform that contains the module. Direct anonymous attestation can be seen as a group signature without the feature that a signature can be opened, i.e., the anonymity is not revocable. Moreover, DAA allows for pseudonyms, i.e., for each signature a user (in agreement with the recipient of the signature) can decide whether or not the signature should be linkable to another signature. DAA furthermore allows for detection of "known" keys: if the DAA secret keys are extracted from a TPM and published, a verifier can detect that a signature was produced using these secret keys. The scheme is provably secure in the random oracle model under the strong RSA and the decisional Di#eHellman assumption.
Digital Signcryption or How to Achieve Cost(Signature
, 1997
"... Abstract. Secure and authenticated message delivery/storage is one of the major aims of computer and communication security research. The current standard method to achieve this aim is “(digital) signature followed by encryption”. In this paper, we address a question on the cost of secure and authen ..."
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Cited by 200 (20 self)
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Abstract. Secure and authenticated message delivery/storage is one of the major aims of computer and communication security research. The current standard method to achieve this aim is “(digital) signature followed by encryption”. In this paper, we address a question on the cost of secure and authenticated message delivery/storage, namely, whether it is possible to transport/store messages of varying length in a secure and authenticated way with an expense less than that required by “signature followed by encryption”. This question seems to have never been addressed in the literature since the invention of public key cryptography. We then present a positive answer to the question. In particular, we discover a new cryptographic primitive termed as “signcryption ” which simultaneously fulfills both the functions of digital signature and public key encryption in a logically single step, and with a cost significantly lower than that required by “signature followed by encryption”. For typical security parameters for high level security applications (size of public moduli = 1536 bits), signcryption costs 50 % (31%, respectively) less in computation time and 85 % (91%, respectively) less in message expansion than does “signature followed by encryption ” based on the discrete logarithm problem (factorization problem, respectively).
An IdentityBased Signature from Gap DiffieHellman Groups
 Public Key Cryptography  PKC 2003, LNCS 2139
, 2002
"... In this paper we propose an identity(ID)based signature scheme using gap DiffieHellman (GDH) groups. Our scheme is proved secure against existential forgery on adaptively chosen message and ID attack under the random oracle model. ..."
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Cited by 188 (4 self)
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In this paper we propose an identity(ID)based signature scheme using gap DiffieHellman (GDH) groups. Our scheme is proved secure against existential forgery on adaptively chosen message and ID attack under the random oracle model.
Secure hashandsign signatures without the random oracle
, 1999
"... We present a new signature scheme which is existentially unforgeable under chosen message attacks, assuming some variant of the RSA conjecture. This scheme is not based on "signature trees", and instead it uses the so called "hashandsign" paradigm. It is unique in that the assu ..."
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Cited by 149 (10 self)
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We present a new signature scheme which is existentially unforgeable under chosen message attacks, assuming some variant of the RSA conjecture. This scheme is not based on "signature trees", and instead it uses the so called "hashandsign" paradigm. It is unique in that the assumptions made on the cryptographic hash function in use are well defined and reasonable (although nonstandard). In particular, we do not model this function as a random oracle. We construct our proof of security in steps. First we describe and prove a construction which operates in the random oracle model. Then we show that the random oracle in this construction can be replaced by a hash function which satisfies some strong (but well defined!) computational assumptions. Finally,we demonstrate that these assumptions are reasonable, by proving that a function satisfying them exists under standard intractability assumptions.
Towards realizing random oracles: Hash functions that hide all partial information
, 1997
"... The random oracle model is a very convenient setting for designing cryptographic protocols. In this idealized model all parties have access to a common, public random function, called a random oracle. Protocols in this model are often very simple and efficient; also the analysis is often clearer. ..."
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Cited by 139 (15 self)
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The random oracle model is a very convenient setting for designing cryptographic protocols. In this idealized model all parties have access to a common, public random function, called a random oracle. Protocols in this model are often very simple and efficient; also the analysis is often clearer. However, we do not have a general mechanism for transforming protocols that are secure in the random oracle model into protocols that are secure in real life. In fact, we do not even know how to meaningfully specify the properties required from such a mechanism. Instead, it is a common practice to simply replace  often without mathematical justification  the random oracle with a `cryptographic hash function' (e.g., MD5 or SHA). Consequently, the resulting protocols have no meaningful proofs of security. We propose a research program aimed at rectifying this situation by means of identifying, and subsequently realizing, the useful properties of random oracles. As a first step, we introduce a new primitive that realizes a specific aspect of random oracles. This primitive, called oracle hashing, is a hash function that, like random oracles, `hides all partial information on its input'. A salient property of oracle hashing is that it is probabilistic: different applications to the same input result in different hash values. Still, we maintain the ability to verify whether a given hash value was generated from a given input. We describe constructions of oracle hashing, as well as applications where oracle hashing successfully replaces random oracles.
PrivacyPreserving Public Auditing for Data Storage Security in Cloud Computing
 In INFOCOM
, 2010
"... Abstract. Cloud Computing is the long dreamed vision of computing as a utility, where users can remotely store their data into the cloud so as to enjoy the ondemand high quality applications and services from a shared pool of configurable computing resources. By data outsourcing, users can be relie ..."
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Cited by 119 (1 self)
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Abstract. Cloud Computing is the long dreamed vision of computing as a utility, where users can remotely store their data into the cloud so as to enjoy the ondemand high quality applications and services from a shared pool of configurable computing resources. By data outsourcing, users can be relieved from the burden of local data storage and maintenance. However, the fact that users no longer have physical possession of the possibly large size of outsourced data makes the data integrity protection in Cloud Computing a very challenging and potentially formidable task, especially for users with constrained computing resources and capabilities. Thus, enabling public auditability for cloud data storage security is of critical importance so that users can resort to an external audit party to check the integrity of outsourced data when needed. To securely introduce an effective third party auditor (TPA), the following two fundamental requirements have to be met: 1) TPA should be able to efficiently audit the cloud data storage without demanding the local copy of data, and introduce no additional online burden to the cloud user; 2) The third party auditing process should bring in no new vulnerabilities towards user data privacy. In this paper, we utilize the public key based homomorphic authenticator and uniquely integrate it with random mask technique to achieve a privacypreserving public auditing system for cloud data storage security while keeping all above requirements in mind. To support efficient handling of multiple auditing tasks, we further explore the technique of bilinear aggregate signature to extend our main result into a multiuser setting, where TPA can perform multiple auditing tasks simultaneously. Extensive security and performance analysis shows the proposed schemes are provably secure and highly efficient. 1