Verification Key Research Articles

Confined Guessing: New Signatures From Standard Assumptions

We put forward a new technique to construct very efficient and compact signature schemes. Our technique combines several instances of only a mildly secure signature scheme to obtain a fully secure scheme. Since the mild security notion we require is much easier to achieve than full security, we can combine our strategy with existing techniques to obtain a number of interesting new (stateless and fully secure) signature schemes. Concretely, we get (1) A scheme based on the computational Diffie–Hellman (CDH) assumption in pairing-friendly groups. Signatures contain \(\mathbf {O}(1)\) and verification keys \(\mathbf {O}(\log k)\) group elements, where \(k\) is the security parameter. Our scheme is the first fully secure CDH-based scheme with such compact verification keys. (2) A scheme based on the (nonstrong) RSA assumption in which both signatures and verification keys contain \(\mathbf {O}(1)\) group elements. Our scheme is significantly more efficient than existing RSA-based schemes. (3) A scheme based on the Short Integer Solutions (SIS) assumption. Signatures contain \(\mathbf {O}(\log (k)\cdot m)\) and verification keys \(\mathbf {O}(n\cdot m) {\mathbb {Z}}_p\)-elements, where \(p\) may be polynomial in \(k\), and \(n,m\) denote the usual SIS matrix dimensions. Compared to state-of-the-art SIS-based schemes, this gives very small verification keys, at the price of slightly larger signatures. In all cases, the involved constants are small, and the arising schemes provide significant improvements upon state-of-the-art schemes. The only price we pay is a rather large (polynomial) loss in the security reduction. However, this loss can be significantly reduced at the cost of an additive term in signature and verification key size.

Secured and Encrypted Data Aggregation with Message Authentication Code in Wireless Sensor Networks

In wireless sensor networks, most of the application requires the transmission of data to base station in a secured manner. The existing techniques necessitate multi-hop forwarding that increases the cost and power utility. Also there is a chance for the malicious nodes to inject the false data during data aggregation and data forwarding. In order to overcome these issues, in this paper, we propose a secured and encrypted data aggregation with message authentication code in wireless sensor network. Initially the aggregator nodes are chosen based on the nodes connectivity. When the data aggregation is in process in the aggregation phase, where the encryption key and the verification key is assigned to the nodes while transmitting to the data aggregator, the MAC is also calculated by aggregator and the monitoring nodes. This helps in verifying the data integrity and false data detection. The monitoring node selection is done by the aggregators. By simulation results, we show that the proposed approach improves the data privacy and also reduces the load and power consumption

Non‐interactive deniable ring signature without random oracles

AbstractRing signature scheme protects the privacy while signer is signing. In the ring signature scheme, the signer can randomly choose verification keys of entities and generate a signature on behalf of these entities. The generated signature can be verified by anyone by inputting all these verification keys. Consequently, a ring signature convinces a verifier that one member from these entities produces this signature without revealing which one. This property is good for the signer as his identity is not leaked. However, the signer also can make use of this capacity to generate a malicious signature on behalf of a ring. Because of the unconditional anonymity of ring signature, this signer cannot be traced to be responsible for his malicious signing. Group signature can avoid this problem because the group manager in the group signature can trace the actual signer by using the trapdoor. However, the group is fixed from the beginning and it needs a complicated setup algorithm. Deniable ring signature was introduced by Komano et al., which allows to revoke the anonymity of actual signer without the manager's help if necessary. The actual signer can confirm his signing for anyone through the confirmation protocol. On the other hand, non‐signers in the ring can disavow this signing by the disavowal protocol. Therefore, the actual signer can be traced. However, Komano's scheme was proven in random oracles, and the traceability protocols (confirmation and disavowal protocols) are interactive. To improve Komano's construction, this work proposes a new efficient non‐interactive deniable ring signature scheme in the standard model. It is a kind of ring signature and therefore, it does not require a setup algorithm, and the ring in the scheme is flexible. Copyright © 2013 John Wiley & Sons, Ltd.

An optical authentication system based on encryption technique and multimodal biometrics

Abstract A major concern nowadays for a biometric credential management system is its potential vulnerability to protect its information sources. To prevent a genuine user's templates from both internal and external threats, a novel and simple method combined optical encryption with multimodal biometric authentication technique is proposed. In this method, the standard biometric templates are generated real-timely by the verification keys owned by legal user so that they are unnecessary to be stored in a database. Compared with the traditional recognition algorithms, storage space and matching time are greatly saved. In addition, the verification keys are difficult to be forged due to the utilization of optical encryption technique. Although the verification keys are lost or stolen, they are useless for others in absence of the legal owner's biometric. A series of numerical simulations are performed to demonstrate the feasibility and performance of this method.

Optical authentication technique based on interference image hiding system and phase-only correlation

An optical authentication technique based on interference image hiding system and phase-only correlation is proposed. In this method, some predefined complex images with different amplitudes and the same phase are respectively encoded into two phase-only masks according to the interference principle. This technique can easily generate different verification keys for different users, so it brings convenience for multi-user application. In the verification stage, both a sharp correlation peak and a significant image represented the identity of a user are generated simultaneously. Therefore, in addition to simple verification, this method can also recognize the identity of the user. Moreover, this technique can effectively avoid the verification key being forged by other person. All the performances and the feasibility of our proposed method are tested by numerical simulations.

The security analysis of a threshold proxy quantum signature scheme

In the YW threshold proxy quantum signature scheme proposed by Yang and Wen, it is found that the basic signature key is the same as the basic verification key, which means that the bitwise exclusive OR (XOR) of the t proxy signature keys is exactly the XOR of the t proxy verification keys. Therefore, the proxy signers can deny their signature and the specific verifiers can forge a legal signature. Furthermore, an attacker can obtain a legal threshold proxy signature for an arbitrary new message. These findings show that there are hidden security loopholes that should be carefully constructed in designing more efficent YW-scheme.

Model generation for quantified formulas with application to test data generation

We present a new model generation approach and technique for solving first-order logic (FOL) formulas with quantifiers in unbounded domains. Model generation is important, e.g., for test data generation based on test data constraints and for counterexample generation in formal verification. In such scenarios, quantified FOL formulas have to be solved stemming, e.g., from formal specifications. Satisfiability modulo theories (SMT) solvers are considered as the state-of-the-art techniques for generating models of FOL formulas. Handling of quantified formulas in the combination of theories is, however, sometimes a problem. Our approach addresses this problem and can solve formulas that were not solvable before using SMT solvers. We present the model generation algorithm and show how to convert a representation of a model into a test preamble for state initialization with test data. A prototype of this algorithm is implemented in the formal verification and test generation tool KeY.

Efficient Convertible Undeniable Signatures with Delegatable Verification

Undeniable signatures, introduced by Chaum and van Antwerpen, require a verifier to interact with the signer to verify a signature, and hence allow the signer to control the verifiability of his signatures. Convertible undeniable signatures, introduced by Boyar, Chaum, Damgard, and Pedersen, furthermore allow the signer to convert signatures to publicly verifiable ones by publicizing a verification token, either for individual signatures or for all signatures universally. In addition, the original definition allows the signer to delegate the ability to prove validity and convert signatures to a semi-trusted third party by providing a verification key. While this functionality is implemented by the early convertible undeniable signature schemes, most recent schemes do not consider this form of delegation despite its practical appeal. In this paper we present an updated definition and security model for schemes allowing delegation, and furthermore highlight a new essential security property, token soundness, which is not formally treated in the previous security models for convertible undeniable signatures. We then propose a new convertible undeniable signature scheme. The scheme allows delegation of verification and is provably secure in the standard model assuming the computational co-Diffie-Hellman problem, a closely related problem, and the decisional linear problem are hard. Furthermore, unlike the recently proposed schemes by Phong et al. and Huang et al., our scheme provably fulfills all security requirements while providing short signatures.

A novel cryptoprocessor architecture for chained Merkle signature scheme

One-time signature schemes rely on hash functions and are, therefore, assumed to be resistant to attacks by quantum computers. These approaches inherently raise a key management problem, as the key pair can be used only for one message. That means, for one-time signature schemes to work, the sender must deliver the verification key together with the message and the signature. Upon reception, the receiver has to verify the authenticity of the verification key before verifying the signature itself. Hash-tree based solutions tackle this problem by basing the authenticity of a large number of verification keys on the authenticity of a root key. This approach, however, causes computation, communication, and storage overhead. Due to hardware acceleration, this paper proposes, for the first time, a processor architecture which boosts the performance of a one-time signature scheme without degrading memory usage and communication properties. This architecture realizes the chained Merkle signature scheme on the basis of Winternitz one-time signature scheme. All operations, i.e., key generation, signing, and verification are implemented on an FPGA platform, which acts as a coprocessor. Timing measurements on the prototype show a performance boost of at least one order of magnitude compared to an identical software solution.

Efficient Provider Authentication for Bidirectional Broadcasting Service

Provider authentication is necessary in bidirectional broadcasting services, and a digital signature scheme is often used to prevent an adversary from attempting impersonation. The cost of secure signing key management is extremely high. In addition, the key has to be updated very often, since it is frequently used. The result is that the verification key also has to be updated very often, and its redistribution cost is huge. These costs are real and substantive problems, especially when the number of users is large. In this paper, we propose a system that dramatically reduces these costs. In the system, the signing key is updated, but the corresponding verification key does not have to be updated. This means that the signing key can be updated without any cost for redistributing the verification key and that the system is secure against the threat of signing key leakage, since the key can be frequently updated. Moreover, we propose a new key management method that divides a conventional key management server's role into two. The use of a key-insulated signature (KIS) scheme enables low-cost and more secure key management with two servers. Finally, to make a bidirectional broadcasting service more secure even if the signing key is leaked, we developed a new strong KIS scheme. We performed an experiment that assessed the cost of our strong KIS scheme and found that it is sufficiently low. Accordingly, a provider authentication system employing this scheme would be more efficient and would have lower key redistribution and network costs in comparison with conventional authentication systems.

Two-Factor Cancelable Biometrics Authenticator

Biometrics-based authentication system offers advantages of providing high reliability and accuracy. However, the contemporary authentication system is impuissance to compromise. If a biometrics data is compromised, it cannot be replaced and rendered unusable. In this paper, a cancelable biometrics-based authenticator is proposed to solve this irrevocability issue. The proposed approach is a two-factor authentication system, which requires both of the random data and facial feature in order to access the system. In this system, tokenized pseudo-random data is coupled with moment-based facial feature via inner product algorithm. The output of the product is then discretized to generate a set of private binary code, coined as 2factor-Hashing code, which is acted as verification key. If this biometrics-based verification key is compromised, a new one can be issued by replacing a different set of random number via token replacement. Then, the compromised one is rendered completely useless. This feature offers an extra protection layer against biometrics fabrication since the verification code is replaceable. Experimental results demonstrate that the proposed system provides zero Equal Error Rate in which there is a clear separation in between the genuine and the imposter distribution populations.

Optical encryption and verification technique for information coding in multiple-wavelengths in Fresnel domain

We propose a new optical encryption and verification technique in which multiple frames of images recorded by different wavelengths can be synchronously encrypted into double pure phase masks (PMs). The height distributions of the two surface-relief PMs are designed by using an iterative phase-retrieval algorithm in combination with the conjugate-gradient method. Two PMs are located at the predesigned positions in the verification system. When a plane wave with a correct wavelength illuminates the optical verification system, the corresponding image is extracted to display on the output plane. Another incident plane wave with other different wavelength which was used in recording can produce another image. Only when all the frames of images recorded by different wavelengths are obtained, the user can then pass through the verification procedure. Compared with the previous encryption and verification technique, these predesigned wavelengths can be used as additional verification keys, which should significantly enhance the security of system. Numerical simulation shows that the proposed technique can successfully reconstruct the verification images for the authorized user having all the correct keys, but never for any unauthorized intruder.

Microprocessor smart cards with fingerprint user authentication

Due to the great increase in Information Technology (IT) systems where user authentication is needed, security in those systems relies on using PINs or passwords. During recent years, the scientific community has been trying to improve biometric techniques to be accepted as an alternative to other user authentication schemes. One of the sectors where user identity must be verified, is the identification cards sector. In fact, if great security wants to be achieved, smart cards should be used. But cardholder verification is performed using Card Holder Verification Keys (CHV-Keys), which are PIN-based. The authors are trying to integrate fingerprint verification inside a smart card, following their works in the past. The fingerprint scheme used is shown, and the work to achieve the integration inside a commercial smart card is detailed.