Search

Homomorphic signature (HS) is a novel primitive that allows an agency to carry out arbitrary (polynomial time) computation f on the signed data m → and accordingly gain a signature σ h for the computation result f (m →) with respect to f on behalf of the data owner (DO). However, since DO lacks control of the agency's behavior, receivers would believe that DO did authenticate the computation result even if the agency misbehaves and applies a function that the DO does not want. To address the problem above, in this paper we introduce a new primitive called authorized function homomorphic signature (AFHS). In AFHS, the agency has to obtain a confidence key sk f from DO in order to evaluate a function f on the data m → and to obtain a signature with which one can check whether the agency acts in accordance with DO's instructions. A black-box construction of AFHS based on HS is given in this paper, and we show that if the underlying primitives are secure, so is our construction under the given security model. Moreover, we provide a somewhat concrete construction that offers stronger security guarantee. [ABSTRACT FROM AUTHOR]

QARMA is a new family of lightweight tweakable block ciphers which is used in the Pointer Authentication of ARMv8.3-A. In this paper, we apply meet-in-the-middle attack to QARMA-64 and QARMA-128 including the outer whitening keys. First, we observe that a linear relation exists between four cells out of the eight input/output cells in the MixColumns operation. Then, the idea of canceling the state difference with the tweak difference is used to make one blank round. Finally, we construct meet-in-the-middle distinguishers on 5-round QARMA-128 and QARMA-64, respectively. Therefore, the attack on QARMA4-128 is obtained by appending three rounds on the top of the distinguisher and two round on the bottom. Similarly, the attack on QARMA3-64 is obtained. Besides, this attack can be extended to attack on 9-round QARMA-64 without increasing the overall complexity. To the best of our knowledge, these are the first attacks on QARMA block ciphers including the outer whitening keys. [ABSTRACT FROM AUTHOR]

TWINE is a lightweight block cipher, which was proposed by NEC corporation in 2012. It is both a good example of common trade-offs in lightweight cryptography and one of the only instances of a GFN with improved diffusion layer. Therefore, its security has attracted amount of attention in recent years. In this paper, we present a meet-in-the-middle attack on 26-round TWINE-128 by exploiting the slow diffusion of key schedule. Specifically, we first construct a new 11-round distinguisher of TWINE. Based on it, we mount a meet-in-the-middle attack on 26-round TWINE-128. The data, time and memory complexities are 2 60 chosen plaintexts, 2 126.18 26-round encryptions and 2 109 64-bit blocks, respectively. Our results are better than all previous ones on TWINE-128 in the single-key scenario if not considering biclique cryptanalysis of TWINE-128. [ABSTRACT FROM AUTHOR]

As a basic and important primitive, hash proof system can be used to construct many cryptographic schemes and protocols. Therefore, it is significant to instantiate more efficient hash proof systems from various assumptions. Although there are many hash proof systems based on various classical assumptions, only a handful of efficient hash proof systems are known based on post-quantum assumptions. In this paper, we present several new hash proof systems based on the standard learning with errors (LWE) problem, which is at least as hard as standard worst-case lattice problems. Comparing with other existing constructions based on lattices, our main advantages are 2-fold: much simpler and more efficient. And our constructions can be easily extended to be identity-based ones and updatable ones. Throughout the paper, our main idea is to base hash proof systems on a new subset indistinguishability problem related to LWE, and employ the property of smooth parameter of q-ary orthogonal lattices to ensure smoothness. [ABSTRACT FROM AUTHOR]

A revocable ID-based broadcast encryption scheme allows an authorized third party to revoke any receiver (decryptor) from the initial receiver set S of the original broadcast ciphertext without the need of decryption. However, the existing revocable ID-based broadcast encryption schemes in the literature cannot fully preserve the receiver privacy and have a large size of ciphertext when the revoked user sets are large. To solve these problems, in this paper, we propose a novel scheme: fully privacy-preserving ID-based broadcast encryption with authorization. Our scheme allows an authorized party to dynamically handle the decryption rights of receivers via an authorized user set L without knowing the message and the identities of the initial receivers. Only those users who are both in S and L can decrypt the ciphertext successfully. The final ciphertext reveals nothing about the identity information of receivers and the authorized users. Our scheme achieves full collusion resistance and is applicable to anonymous data sharing where the receivers are decided by the authorized third party (or multiple authorized third parties) excluding the data owner. We show that our proposed scheme is provably secure under the defined security models in the random oracle model. [ABSTRACT FROM AUTHOR]

A group key establishment enables a group key shared among all group members. In this paper, we proposed a novel group key establishment, which is a hybrid of the Diffie-Hellman (DH) public-key scheme and the secret sharing scheme. Our protocol takes the advantages of the DH scheme, which does not need a mutually trusted key generation center (KGC) and the secret sharing scheme, which reduces the computational time. Employing the DH scheme allows any group member to act as a KGC to distribute a secret key to all group members. The secret sharing scheme is used as the encryption tool to transfer a group key to group members. Since public-key encryption involves modular exponentiations using a larger modulus (say at least 1024 bits) as compared with the secret sharing encryption involves polynomial operations using a smaller modulus (say only 160 bits), our proposed approach is faster than the broadcast encryption in public-key setting. We show that our protocol can provide key secrecy, key authentication and key independence. [ABSTRACT FROM AUTHOR]

Recently, Zhang et al. proposed a new anonymous hierarchical identity-based encryption (anonymous HIBE) over prime order groups to achieve both constant size private key and constant size ciphertext. Moreover, a double exponent technique was used to provide anonymity. They proved that their scheme is secure and anonymous against chosen plaintext attacks in the standard model. In this paper, we point out that their scheme is insecure. [ABSTRACT FROM AUTHOR]

Advances in quantum computers threaten the security of public-key cryptosystems whose security is based on the hardness of factoring or on the discrete logarithm problem. Multivariate encryption schemes are promising alternatives to traditional cryptosystems. Tao et al. proposed a new Multivariate Public-Key Cryptosystem for encryption called simple matrix encryption scheme (ABC for short). Further, they proposed an improved simple matrix encryption schemes and a cubic simple matrix encryption scheme. In this paper, we show that the three schemes are vulnerable to a structural key recovery attack by tensor and vectorization notation and associated algebraic re-writing rules. We derive a set of linear equations from the public key whose solution yields an equivalent key pair that hide the central map. The proposed cryptanalysis approaches require polynomial computational complexity to achieve some equivalent keys from associated public keys. In addition, we provide an example to illustrate feasibility of proposed analysis method. [ABSTRACT FROM AUTHOR]

ℱ -Related-Key Attacks (RKAs) allow an adversary to tamper the key k stored in a cryptographic device by specifying related-key deriving (RKD) functions f in ℱ and subsequently learn the outcome of the device under related keys f (k) ⁠. In this paper, we present RKA secure public-key encryption (PKE) and symmetric encryption (SE) schemes admitting a tight security reduction to the standard s -Linear assumption. The security loss depends only on the security parameter and is independent of the number of tampering queries made by the adversary. Our encryption schemes are resilient to RKAs w.r.t. the set of restricted affine functions ℱ raff ⁠, of which the set of linear functions ℱ lin is a subset. In particular, • Our encryption schemes serve as the first ones possessing tight RKA security for a non-trivial RKD function class ℱ under standard assumptions. • Moreover, our encryption schemes enjoy tight super-strong RKA securities, which are the strongest ones among the existing RKA security notions. [ABSTRACT FROM AUTHOR]

Due to its great efficiency and quantum resistance, public key cryptography based on Ring-LWE problem has drawn much attention in recent years. A batch of cryptanalysis works provided ever-improved security estimations for various Ring-LWE schemes, but few works discussed the security of Ring-LWE cryptography from kleptographic aspect. In this paper, we show how to embed a backdoor into a classic Ring-LWE encryption scheme so that partial bits of the plaintext are leaked to the owner of the backdoor. By theoretical analysis and experimental observations, we argue that the klepto Ring-LWE encryption scheme with such backdoor is feasible and practical. [ABSTRACT FROM AUTHOR]

In this paper, we examine a method of constructing a self-synchronizing stream cipher referred to as statistical cipher feedback (SCFB). Although recently studied as a mode for block ciphers, we explicitly consider the application of SCFB to hardware-oriented stream ciphers. Specifically, we show that SCFB can be used to realize a self-synchronizing stream cipher that has the characteristics of compact, efficient hardware implementations and is secure given that the underlying synchrononous stream cipher is secure. Further, we consider the communication properties of the SCFB system and examine the relationships between these properties and the implementation characteristics. [ABSTRACT FROM AUTHOR]

The Database-As-a-Service (DaaS) model provides seamless mechanisms for database management and service. As a countermeasure to security treats, encryption technologies have been widely adopted in database systems. Accordingly, privacy-preserving queries on encrypted databases has become an important research topic. In this paper, we present the first solution of authorized equi-join for multiple data contributors in the PKC-based setting. With the improved ciphertext security under checkability, our underlying cryptographic construction could be used independently as a standard procedure for many other relational operations, for instance, intersection, difference, and set union. As a feature, our scheme allows flexible authorization policies for the join operation by the controlled trapdoor transitivity, which has not yet been studied thoroughly in the literature. Our proposed scheme is efficient in encryption and execution and has a reasonable ciphertext size. It can be applied as a building block for data query in the DaaS model. [ABSTRACT FROM AUTHOR]

In this paper, we consider the problem of cheating for visual cryptography schemes. Although the problem of cheating has been extensively studied for secret sharing schemes, little work has been done for visual secret sharing. We provide a formal definition of cheating for visual cryptography and new (2, n)-threshold and (n, n)-threshold schemes that are immune to deterministic cheating. [ABSTRACT FROM PUBLISHER]

In this paper, we introduce a new side-channel attack using block cipher cryptanalysis named a meet-in-the-middle attack. Using our new side-channel technique we show that advanced encryption standard (AES) with reduced 10 masked rounds is broken, which is faster than the exhaustive key search attack. This implies that one has to mask the entire rounds of the 12-round 192-bit key AES to prevent our attacks. Our result is the first one to analyse AES with reduced 10 masked rounds, while the previous best known side-channel attack is on AES with reduced eight masked rounds. [ABSTRACT FROM PUBLISHER]

Visual cryptography schemes allow the encoding of a secret image, consisting of black or white pixels, into n shares which are distributed to the participants. The shares are such that only qualified subsets of participants can visually recover the secret image. The secret pixels are shared with techniques that subdivide each secret pixel into a certain number m, m = 2 of subpixels. Such a parameter m is called pixel expansion. Recently Yang introduced a probabilistic model. In such a model the pixel expansion m is 1, that is, there is no pixel expansion. The reconstruction of the image however is probabilistic, meaning that a secret pixel will be correctly reconstructed only with a certain probability. In this paper we propose a generalization of the model proposed by Yang. In our model we fix the pixel expansion m = 1 that can be tolerated and we consider probabilistic schemes attaining such a pixel expansion. For m = 1 our model reduces to the one of Yang. For big enough values of m, for which a deterministic scheme exists, our model reduces to the classical deterministic model. We show that between these two extremes one can trade the probability factor of the scheme with the pixel expansion. Moreover, we prove that there is a one-to-one mapping between deterministic schemes and probabilistic schemes with no pixel expansion, where contrast is traded for the probability factor. [ABSTRACT FROM AUTHOR]

Cryptographic systems refer to a set of algorithms needed to implement a particular form of encryption, decryption, signature and verification, which have practical applications in engineering area. Among cryptographic systems, Multivariate Public Key Cryptography (MPKC) is one of the most popular post-quantum candidates since it has the potential to resist quantum computer attacks. MPKC must be protected against a wide range of attacks, including side-channel attack, which is any attack based on information gained from the physical implementation of cryptographic systems. However, there are few side-channel attacks on MPKC schemes. In this paper, we present techniques to exploit Differential Power Analysis and fault analysis attacks for analyzing the effectiveness of side-channel attacks on MPKC schemes. We propose a general model of side-channel attacks on enhanced Tame Transformation Signature (enTTS) scheme, which is one of the representative MPKC schemes. We implement a naive enTTS scheme on Application Specific Integrated Circuits and propose a successful side-channel attack on the implementation. Experimental results show that our attack successfully obtains all the pieces from the private keys of the enTTS scheme and they clearly demonstrate the importance of protecting MPKC against side-channel attacks. [ABSTRACT FROM AUTHOR]

Certificateless signcryption (CLSC) can simultaneously fulfill certificateless encryption and certificateless signature; however, most CLSC schemes need costly computational overhead due to the usage of pairing operations. How to improve its computational efficiency is a very significant research problem. In this paper, we propose a pairing-free and secure CLSC scheme. In the random oracle model, the proposed scheme is indistinguishability against adaptive chosen-ciphertext attacks secure in confidentiality and unforgeability against adaptive chosen-message attacks secure in unforgeability. In the new scheme, only a designated receiver can recover the message, and a third party can verify the validity of a signcrypted text without knowing the receiver's secret value. In addition, this cryptographic algorithm is very appropriate to applications in online auction, email system and private contractual signature. [ABSTRACT FROM AUTHOR]

At present, 'mixed-type' multivariate schemes are relatively rare except the Dragon scheme and its variants (Little Dragon Two scheme and Poly-Dragon scheme). However, they are insecure. In this paper, we first define a particular polynomial called Three-color Polynomial (this polynomial has three-class variables, and the form of the associated symmetric matrix of its quadratic part is similar to the 'three-color model' in colorimetry. So we call it three-color polynomial), and its corresponding Three-color Map. Based on the three-color map, we then present a mixed multivariate signature scheme named RGB (it means Red–Green–Blue, because the central map of this scheme is a threecolor map, and the 'three-color' stands for RGB in colorimetry), which is a variant of the Unbalanced Oil–Vinegar (UOV) signature scheme. Compared with UOV, each polynomial of the central map of RGBhas more cross-terms among all the variables {Y, Z, T}. The variable Y has much to do with message values.To a certain degree, the variable Y stands for the message values. This means that the message values can be more fully mixed with other variable values in the central map, and the adversary is very difficult to forge the signature. Thus, in theory RGB is more secure than UOV. Through detailed analysis, we find thatRGBcan resist current known algebraic attacks under proper parameters, such as exhaustive search attack, separation attack, MinRank attack and direct attack (other algebraic attacks are inapplicable for RGB). Besides, our experiments show that under choosing the security level of 280, the signing time of Magma implementation of RGB is 0.046 s on an ordinary Linux-PC with 2.50 GHz, and the signing time of its C implementation is ∼0.003 s on an 800MHz machine. The comparisons show that the signing speed of RGB is faster than that of Sflashv2, Quartz, UOV, Rainbow and RSA-1024, and is slightly slower than that of ECDSA-163 and NTRUSign-251. Overall, this new scheme can attain very good performance in terms of security and efficiency. [ABSTRACT FROM AUTHOR]

The concept of Ephemerizer, proposed by Perlman, is a cryptographic primitive for assured data deletion. With an Ephemerizer protocol, data in persistent storage devices will always be encrypted simultaneously using an ephemeral public key of the Ephemerizer (an entity that will publish a set of ephemeral public keys and periodically delete the expired ones) and the long-term public key of a user. An Ephemerizer protocol enables the user to securely decrypt the encrypted data without leaking any information to the Ephemerizer. So far, no security model has ever been proposed for this primitive and existing protocols have not been studied formally. Not surprisingly, we show that some existing Ephemerizer protocols possess security vulnerabilities. In this paper, we review the notion of Timed-Ephemerizer, which can be regarded as a hybrid primitive by combining Ephemerizer and timed-release encryption. Compared with an Ephemerizer protocol, a Timed-Ephemerizer protocol further guarantees that data will only be released after a pre-defined disclosure time. Moreover, we revisit a security model for Timed-Ephemerizer and adapt it for Ephemerizer. We also revise a previous Timed-Ephemerizer protocol by Tang and prove its security in the security model. [ABSTRACT FROM AUTHOR]

Presently, many identity-based proxy signature (IBPS) schemes have been proposed, but most of them are constructed in the random oracle model. Also, the proposed security model for IBPS is not enough complete according to Boldyreva's work. Cao and Cao proposed an IBPS scheme in the standard model. However, their scheme is not secure because of not resisting the attack of delegator and requires more computation cost. In this paper, we present a framework for IBPS and show a detailed security model for IBPS. Under our framework, we present an efficient IBPS scheme in the standard model. Compared with other IBPS schemes, the proposed scheme has more complete security and is more efficient. [ABSTRACT FROM AUTHOR]

In this paper, we introduce a general paradigm called identity-based extractable hash proof system (IB-EHPS), which is an extension of extractable hash proof system (EHPS) proposed by Wee (CRYPTO'10). We show how to construct identity-based key encapsulation mechanism (IB-KEM) from IB-EHPS in a simple and modular fashion. Our construction provides a generic method of building and interpreting CCA-secure IB-KEMs based on computational assumptions. As instantiations, we realize IB-EHPS from the bilinear Diffie–Hellman assumption and the modified bilinear Diffie–Hellman assumption, respectively. Besides, we carefully investigate the relation between EHPS and IB-EHPS, and indicate possible refinement and generalization of EHPS. [ABSTRACT FROM PUBLISHER]

A signcryption scheme allows a sender to produce a ciphertext for a receiver so that both confidentiality and non-repudiation can be ensured. It is built to be more efficient and secure, for example, supporting insider security, when compared with the conventional sign-then-encrypt approach. In this paper, we propose a new notion called heterogeneous signcryption in which the sender has an identity-based secret key while the receiver is holding a certificate-based public key pair. Heterogeneous signcryption is suitable for practical scenarios where an identity-based user, who does not have a personal certificate or a public key, wants to communicate securely with a server which has a certificate with its public key. We propose two constructions and show their security under the model we define in the random oracle model. The model we define captures the insider security for both confidentiality and unforgeability. Both of the schemes also support public verifiability and key privacy, that is, an adversary cannot find out who the sender and receiver are from a ciphertext in the insider security model. The second scheme is the most efficient one computationally among all key-privacy-preserving signcryption schemes even when compared with schemes in an identity-based cryptographic setting or certificate-based public key setting. [ABSTRACT FROM PUBLISHER]

The identity (ID)-based public-key system using bilinear pairings defined on elliptic curves offers a flexible approach to simplify the certificate management. In 2006, the IEEE P1363.3 committee has defined the ID-based public-key system with bilinear pairings as one of public-key cryptography standards. In this, an authenticated key agreement (AKA) protocol is one important issue that provides mutual authentication and key exchange between two parties. Owing to the fast growth of mobile networks, the computational cost on the client side with low-power computing devices is a critical factor in designing an AKA protocol suited for mobile networks. In this paper, we present an efficient and secure ID-based mutual authentication and key exchange protocol using bilinear pairings. Performance analysis and experimental data are given to demonstrate that our proposed protocol is well suited for a client–server environment with low-power mobile devices. In comparison with the recently proposed ID-based protocols, our protocol has the best performance on the client side. [ABSTRACT FROM PUBLISHER]

In this paper, a low-complexity Programmable Cellular Automata (PCA) based reconfigurable architecture is proposed. Through simple configurations, it cannot only be used in the PCA-based block cipher of symmetric-key encryption, but also can be configured to be an efficient versatile modular multiplier in GF(2m), an essential operation in public-key cryptography. The proposed reconfigurable hybrid-crypto architecture has a regular structure and is very suitable for high speed VLSI implementation, increasing the flexibility of security schemes and reducing the total cost of the hybrid cryptosystems. Moreover, the low-cost serial implementation of this reconfigurable architecture is feasible in restricted computing environments, such as embedded systems and wireless devices. [ABSTRACT FROM AUTHOR]

In practice, when the security of a block cipher implementation is considered, the leakages related to the outer rounds encryptions can be used by side channel attacks (SCA) to recover the secret key. Therefore, the outer rounds of block cipher implementations should be protected. However, in order to lower the implementation price, the inner rounds of block cipher implementations may be unprotected. In light of this, the security of an outer rounds protected DES implementation is considered. In detail, template attack (TA), which is information theoretically the strongest SCA style, can be used to obtain the inner round output. Then, linear cryptanalysis (LC) can be used to recover the secret key. Finally, the optimal key enumeration algorithm can be used to optimize the efficiency of TA assisted LC. We evaluate the efficiency of TA assisted LC in simulated scenarios where a three outer rounds protected DES implementation is targeted. The evaluation results show that when 800 correct samples are available and the number of key enumeration is |$2^{10}$|⁠ , the efficiency of TA assisted LC can reach 83% of success rate. Overall, an efficient combination attack style that can be used to accurately evaluate the security of an outer rounds protected DES implementation is proposed. [ABSTRACT FROM AUTHOR]

The Visual cryptography scheme (VCS) is a perfect secure method that encrypts a secret image by breaking it into shadow images. A distinctive property of VCS is that one can visually, without computation, decode the secret by superimposing shadow images. However, much of the contrast of the reconstructed image is lost. A different kind of VCS has been recently proposed by Viet and Kurosawa, called VCS with reversing, allowing participants to perform a reversing operation (reverse black and white) on shadow images. Two drawbacks of the Viet–Kurosawa VCS are: (1) one can only reconstruct an almost ideal contrast image but not an ideal contrast image and (2) the Viet–Kurosawa VCS is constructed just from a perfect black VCS. This paper shows a real perfect contrast VCS such that the black and white pixels are perfectly reconstructed within finite runs, no matter what VCS (perfect black or non-perfect black) is used. [ABSTRACT FROM AUTHOR]

We propose a fully homomorphic encryption (FHE) scheme that encrypts matrices. Our scheme supports homomorphic matrix addition, multiplication and Hadamard product. In PKC 2015, Hiromasa et al. constructed the only FHE scheme that encrypts matrices and supports homomorphic matrix addition and multiplication. Compared with their work, the advantages of our scheme are the following: (1) Small ciphertext size : For a plaintext matrix M ∈ {0,1} r × r ⁠, the size of ciphertext matrix is r × (n + r) ⁠, in contrast to (n + r) × (n + r) ⌈ log q ⌉ in their work. (2) Standard assumption : The security is based on LWE assumption merely, while the security of scheme in their work depends additionally on some special kind of circular security assumption. (3) Supporting homomorphic matrix Hadamard product. We show how to apply the proposed scheme to optimize the bootstrapping procedure of Alperin-Sheriff and Peikert, in a way similar to the work of Hiromasa, Abe and Okamoto. Due to smaller ciphertext matrices, the bootstrapping key of our optimized bootstrapping procedure is smaller than that in the work of Hiromasa, Abe and Okamoto by a factor of (n / r + 1) ⌈ log q ⌉ ⁠. [ABSTRACT FROM AUTHOR]

In recent years, much attention has been focused on designing provably secure public-key encryption (PKE) scheme in the presence of key-leakage. However, most of them are researched in the bounded-leakage model, and cannot keep their claimed security in the continuous leakage setting. What's more, most of traditional leakage-resilient PKE schemes cannot ensure that all of elements in ciphertext are random from the adversary's view, and any polynomial time adversary can get leakage on the secret key from the corresponding ciphertext. But, in the real world, an adversary can trivially break the security of PKE scheme under the continuous leakage attacks. To get an efficient PKE scheme which can keep its original security in the continuous-leakage model, we propose a new construction of chosen-ciphertext attacks secure PKE scheme, and whose security is based on the hardness of the classical decisional Diffie-Hellman assumption and the target collision resistance of the hash function. Our method not only can tolerate continuous leakage attacks on the secret key through key update operation, but also enjoys better performances, such as the round leakage parameter λC ≤ log q - ω(log k) (k is the security parameter, q is a big prime order of the underlying group.) is independent of the plaintext space, and has the constant size, also, any polynomial time adversary unable to obtain leakage on the secret key from the corresponding ciphertext, etc. Because of these good performance features, our proposal may have some significant value in the practical applications. [ABSTRACT FROM AUTHOR]

Related-key attacks (RKAs) are a flavor of powerful physical attacks, which allow an adversary to modify the secret key stored in a cryptographic device and subsequently observe the effect of such modifications on the output of the device. Designing secure encryption schemes against such attacks is a challenging task, especially for a large class of such physical attacks which are usually captured by related-key derivation functions. In this work, we achieve the security of public key encryptions (PKEs) against a new and broad function class that consists of almost all efficiently invertible functions in two different ways. Specifically, we first give a generic construction of PKE which is proven secure against such a broad function class under the standard chosen-ciphertext security. Moreover, we present two practical concrete constructions, both of which are shown to be secure against such function class under standard assumptions in the standard model. At last, we give a detailed performance analysis, which shows that our constructions can not only resist to a large class of RKAs but also achieve a good efficiency. [ABSTRACT FROM AUTHOR]

In mobile environments, data stored in nodes are subject to side-channel attacks such as power analysis, emitted signal, detected radiation, etc. In this work, we propose a leakage-resilient inner-product encryption that the decryption will succeed if and only if the decryption attribute vector (generate the token) meets the orthogonal encryption attribute vector (obfuscated encryption policy), that is, the match holds that the inner product of two vectors is zero. Propose scheme supports the security of attribute-hiding and leakage-resilient in the standard model. The adversary cannot only issue any token reveal query on non-match vector, but also can request at most ℓ-bit information on the token-leakage query even if the queried vector matches the challenge vector. We prove the security by the technique of dual system encryption in the orthogonal subgroups, to be strongly leakage-resilient and adaptively attribute-hiding. We also deploy our scheme as a building block to devise a secure twoparty point/polynomial evaluation protocol in mobility environments, in which two parties cooperate to evaluate a polynomial in the sense that their sensitive inputs of both point and polynomial are fully preserved. Finally, we assess the performance of leakage resilience including the leakage bound and the leakage fraction (LF). Analysis shows that the leakage bound is approximate (n − 1) log π2 and the LF is about 1/2(1 + ω1 + ω3), where n is the length of vector, π2 is the order of subgroupGπ2 and ω1, ω3 are the constants. We can obtain optimized LF 1/2 − o(1) by varying the sizes of subgroups. [ABSTRACT FROM AUTHOR]

We propose enhancing a reconfigurable and extensible embedded reduced instruction set computer (RISC) processor core with a protected zone for isolated execution of cryptographic algorithms. The protected zone is a collection of processor subsystems such as functional units optimized for high-speed execution of integer operations, a small amount of local memory for storing sensitive data during cryptographic computations, and special-purpose and cryptographic registers to execute instructions securely. We outline the principles for secure software implementations of cryptographic algorithms in a processor equipped with the proposed protected zone.We demonstrate the efficiency and effectiveness of our proposed zone by implementing the most-commonly used cryptographic algorithms in the protected zone; namely RSA, elliptic curve cryptography, pairingbased cryptography, Advanced Encryption Standard (AES) block cipher, and secure hash algorithm (SHA)-1 and SHA-256 cryptographic hash functions. In terms of time efficiency, our software implementations of cryptographic algorithms running on the enhanced core compare favorably with equivalent software implementations on similar processors reported in the literature. The protected zone is designed in such a modular fashion that it can easily be integrated into any RISC processor. The proposed enhancements for the protected zone are realized on an field programmabel gate array (FPGA) device. The implementation results on the FPGA confirm that its area overhead is relatively moderate in the sense that it can be used in many embedded processors. Finally, the protected zone is useful against cold-boot and micro-architectural side-channel attacks such as cache-based and branch prediction attacks. [ABSTRACT FROM AUTHOR]

Motivated by perfect guessing security for private key encryption by Alimomeni and Safavi-Naini (ICITS 2012), we study the relations between various unconditional ε-security notions, including $\epsilon$-guess security, ε-min entropic security and ε-Shannon security. We characterize the relations between these security notions. Our results stem from the essential mathematical properties of the underlying measures (i.e. guessing probability, min entropy and Shannon mutual information). We also prove the lower bound on either key entropy or key size or key min entropy for these models. Our results show that the ε-security under these models has a large key size or (min) entropy and hence impossible to be efficient. [ABSTRACT FROM PUBLISHER]

We present a tool for automatic analysis of computational indistinguishability between two strings of information. This is designed as a generic tool for proving cryptographic security based on a formalism that provides computational soundness preservation. The tool has been implemented and tested successfully with several cryptographic schemes. [ABSTRACT FROM PUBLISHER]

Recent research shows that many public-key or identity-based encryption schemes are vulnerable to side-channel attacks on the keys by the interaction of an adversary with a physical device. To tolerate the possible key leakage, leakage-resilient cryptography models a class of leakage output by allowing the adversary to be able to specify a computable leakage function and obtaining the partial keys or other possibly internal states from the output of function. In this article, we propose a leakage-resilient hidden-vector encryption (HVE) scheme that supports the predicate operators such as conjunction, disjunction, comparison, range query and subset query, etc. The proposed scheme is leakage-resilient attribute-hiding secure in the sense that the adversary cannot only obtain the tokens of non-match vectors but also learn amount of key information of the vector that matches the challenge vector. To the best of our knowledge, this is the first HVE that supports token-leakage resilience. We prove the security with a series of computationally indistinguishable games that uses the dual system encryption mechanism. We also analyze and discuss the performance of leakage bound parameters and leakage fraction in the practical security level. Finally, we also give an extensive scheme to achieve the security of both attribute-hiding and payload-hiding, and analyze the performance in larger alphabets. [ABSTRACT FROM PUBLISHER]

We proposed an image signature method for content authentication, which applies a hierarchical approach to construct an image signature. In the first level, DWT and DCT are used to extract image features; then these features are encrypted by using sub-keys that are generated by a cryptographically hash function. In the second level, Karhunen–Loeve transformation is used to reduce the signature length. The main features of the proposed method are as follows: (i) It achieves a trade-off between robustness and tampering sensitivity. (ii) It provides a tool for image tampering detection and tampering localization. (iii) It can be used to detect the thumbnail of the large image to improve detection efficiency. (iv) It provides the compact signature, and the signature length is independent of the image size. Experimental results show that proposed method is robust for content-preserving manipulations such as JPEG compression, adding noise, filtering and Gamma correction, etc. [ABSTRACT FROM PUBLISHER]

A salient aspect of protection system design is the set of the mechanisms for the representation, distribution, verification and revocation of access privileges. With reference to a segmented virtual memory space, we present an approach that is based on the use of symmetric-key cryptography to represent segment pointers, including access right specifications. Our design effort has been guided by three main objectives: (i) to maintain the simplicity of access privilege representation that characterizes classical capability and password-capability systems; (ii) to keep the memory requirements low even in the case of complex access privileges expressed in terms of several access rights; and (iii) to allow an easy implementation of effective techniques for access privilege review and revocation. [ABSTRACT FROM PUBLISHER]