Lattice-based linearly homomorphic signature scheme over binary field

Authentication of public keys in asymmetric cryptography is an important objective to fulfil. Identity-based schemes are an efficient solution for this scenario. There are various identity-based schemes that are based on either factoring problem or DLP problem, but these problems can be solved in polynomial time using quantum computers. Multivariate cryptography is one of the main alternatives for the construction of post-quantum digital signature schemes. Digital signature construction needs modest computations in multivariate public key cryptography, so these schemes are considered quite efficient. In this paper, we present a new identity-based signature scheme in which the signature size and user key size are relatively small. The design of our proposed signature scheme is based on MQDSS construction.KeywordsMultivariate public key cryptographyMQ problemIdentity-based signature scheme

This paper presents the proposal of a new implicit and explicit certificate-based signature scheme (IE-CBS-kCAA scheme) using Sakai–Kasahara’s type keys. The scheme security depends on the computational difficulty of solving the modified collusion attack algorithm with ${k}$ traitors ( ${k}$ -mCAA problem), reducible in particular cases to the known ${k}$ -CAA problem. The originality of the scheme consists not only in the formulation and application of a new difficult computational problem but also in its design to meet the paradigm of public key cryptography based on implicit and explicit certificates. Due to such an approach, the proposed signature scheme can be used in the traditional public key infrastructure with the revocation of explicit certificates and in non-standard infrastructures without the revocation of implicit certificates. In this paper, the security model is formulated and it is shown that the IE-CBS-kCAA signature scheme is existentially unforgeable against adaptively chosen messages in the random oracle model. Moreover, it results from the comparison of the IE-CBS-kCAA scheme with other signature schemes based on implicit and/or explicit certificates that its computational efficiency is at a similar level. Computational tests have also shown that the scheme can be used in practice.

Kakvi and Kiltz (EUROCRYPT'12) proposed the first tight security reduction for RSA full domain hash signature scheme (RSA-FDH) with public exponent e < N1/4 in the random oracle (RO) model, and they left an open problem which called for a tightly secure RSA-FDH for N1/4 < e < N. In this paper, we consider the improved RSA (iRSA) trapdoor functions, introduced by Cao (Science in China'01), are functions that the security can be strictly proved to be equivalent to the factoring. We show that iRSA-FDH has a tight security reduction for e < N. Technically we construct iRSA lossy trapdoor functions, and then we apply the lossiness of the iRSA trapdoor functions to obtain tight security reductions for iRSA-FDH in the RO model. Finally, we propose a tightly secure blind signature scheme based on our iRSA lossy trapdoor functions in the RO model.

Efficient incremental authentication for the updated data in fog computing

In cloud and edge computing, senders of data often want to be anonymous, while recipients of data always expect that the data come from a reliable sender and they are not redundant. Linkable ring signature (LRS) can not only protect the anonymity of the signer, but also detect whether two different signatures are signed by the same signer. Today, most lattice-based LRS schemes only satisfy computational anonymity. To the best of our knowledge, only the lattice-based LRS scheme proposed by Torres et al. can achieve unconditional anonymity. But the efficiency of signature generation and verification of the scheme is very low, and the signature length is also relatively long. With the preimage sampling, trapdoor generation, and rejection sampling algorithms, this study proposed an efficient LRS scheme with unconditional anonymity based on the e-NTRU problem under the random oracle model. We implemented our scheme and Torres et al.'s scheme, as well as other four efficient lattice-based LRS schemes. It is shown that under the same security level, compared with Torres et al.'s scheme, the signature generation time, signature verification time, and signature size of our scheme are reduced by about 94.52%, 97.18%, and 58.03%, respectively.

In this paper, we present an evaluation of possible ARM instruction set extension for elliptic curve cryptography (ECC) over binary finite fields GF(2/sup m/). The use of elliptic curve cryptography is becoming common in embedded domain, where its reduced key size at a security level equivalent to standard public-key methods (such as RSA) allows for power consumption savings and more efficient operation. ARM processor was selected because it is widely used for embedded system applications. We developed an ECC benchmark set with three widely used public-key algorithms: Diffie-Hellman for key exchange, digital signature algorithm, as well as El-Gamal method for encryption/decryption. We analyzed the major bottlenecks at function level and evaluated the performance improvement, when we introduce some simple architectural support in the ARM ISA. Results of our experiments show that the use of a word-level multiplication instruction over binary field allows for an average 33% reduction of the total number of dynamically executed instructions, while execution time improves by the same amount when projective coordinates are used.

Digital signature with proxy delegation, which is a secure ownership enforcement tool, allows an original signer to delegate signature rights to a third party called proxy, so that the proxy can sign messages on behalf of the original signer. In today’s modern society, many applications use this mechanism. Several types of delegations are quite prevalent and the delegation of signing authority is one of them. In a traditional digital signature scheme, signer transmits signature along with message for verification, which leads to additional communication, computation cost and requires extra bandwidth. To resolve these issues, in this paper, we present an efficient ID-based proxy signature scheme with message recovery using bilinear pairings. Because of the message recovery feature, the proxy signer need not send the message to the verifier, so that the proposed scheme reduces the bandwidth requirement and communication cost. Our proposed scheme is proven secure against existential forgery under adaptively chosen message and identity attacks in the random oracle model (ROM) with the assumption that the Computational Diffie-Hellman Problem (CDHP) is intractable. We compare our scheme with related schemes. The efficiency analysis shows that the scheme is computationally efficient. Thus the proposed ID-based proxy signature scheme is secure and efficient both in terms of computation and communication costs than the related existing schemes.

SummaryIn a short signature scheme, the length of signature is much smaller than that of the general signature. Short signatures are widely used in low‐computation, low‐storage, and low‐bandwidth communication environments. The proof of security of all certificateless short signature schemes currently known is given in the random oracle model. In this paper, a new certificateless short signature scheme is constructed, and it is proved to be unforgeable in the standard model. Taken into account the computation costs, the scheme performs only one pairing operation, so it is more efficient than previous ones.

Formal models and security proofs are especially important for multisignatures: in contrast to threshold signatures, no precise denitions were ever provided for such schemes, and some proposals were subsequently broken. In this paper, we formalize and implement a variant of multi-signature schemes, Accountable-Subgroup Multisignatures (ASM). In essence, ASM schemes enable any subgroup,S, of a given group,G, of potential signers, to sign eciently a message M so that the signature provably reveals the identities of the signers in S to any verier. Specically, we provide: 1. The rst formal model of security for multisignature schemes that explicitly includes key generation (without relying on trusted third parties); 2. A protocol, based on Schnorr’s signature scheme [Sch91], that is both provable and ecient: Only three rounds of communication are required per signature. The signing time per signer is the same as for the single-signer Schnorr scheme, regardless of the number of signers. The verication time is only slightly greater than that for the single-signer Schnorr scheme. The signature length is the same as for the single-signer Schnorr scheme, regardless of the number of signers. Our proof of security relies on random oracles and the hardness of the Discrete Log Problem.

An efficient and provable certificate-based proxy signature scheme for IIoT environment

Vehicular ad hoc networks (VANETs) have become an essential part of the intelligent transportation system because they provide secure communication among vehicles, enhance vehicle safety, and improve the driving experience. However, due to the openness and vulnerability of wireless networks, the participating vehicles in a VANET system are prone to a variety of cyberattacks. To secure the privacy of vehicles and assure the authenticity, integrity, and nonrepudiation of messages, numerous signature schemes have been employed in the literature on VANETs. The majority of these solutions, however, are either not fully secured or entail high computational costs. To address the above issues and to enable secure communication between the vehicle and the roadside unit (RSU), we propose a certificateless aggregate signature (CLAS) scheme based on hyperelliptic curve cryptography (HECC). This scheme enables participating vehicles to share their identities with trusted authorities via an open wireless channel without revealing their identities to unauthorized participants. Another advantage of this approach is its capacity to release the partial private key to participating devices via an open wireless channel while keeping its identity secret from any other third parties. A provable security analysis through the random oracle model (ROM), which relies on the hyperelliptic curve discrete logarithm problem, is performed, and we have proven that the proposed scheme is unforgeable against Type 1 (FGR1) and Type 2 (FGR2) forgers. The proposed scheme is compared with relevant schemes in terms of computational cost and communication overhead, and the results demonstrate that the proposed scheme is more efficient than the existing schemes in maintaining high-security levels.

Let us consider a situation where a client (Alice) frequently buys a certain kind of product from a shop (Bob) (e.g., an online music service sells individual songs at the same price, and a client buys songs multiple times in a month). In this situation, Alice and Bob would like to aggregate the total transactions and pay once per month because individual payments are troublesome. Though optimistic fair exchange (OFE) has been considered in order to swap electronic items simultaneously, known OFE protocols cannot provide such aggregate function efficiently because various costs are bounded by the number of transactions in the period. In order to run this aggregation procedure efficiently, we introduce a new kind of OFE called accumulable OFE (AOFE) that allows clients to efficiently accumulate payments in each period. In AOFE, any memory costs, computational costs, and communication complexity of the payment round must be constant in terms of the number of transactions. Since a client usually has just a low power and poor memory device, these efficiencies are desirable in practice. Currently, known approaches (e.g., based on verifiably encrypted signature scheme) are not very successful for constructing AOFE. Thus, we consider a new approach based on a new cryptographic primitive called verifiably encrypted homomorphic signature scheme (VEHS). In this paper, we propose a generic construction of AOFE from VEHS and also present a concrete VEHS scheme over a composite-order bilinear group by using the dual-form signature techniques. This VEHS scheme is also of independent interest. Since we can prove the security of VEHS without random oracles, our AOFE protocol is also secure without random oracles. Finally, we implemented our AOFE protocol, and it is efficient enough for practical use.

ESIGN is an efficient digital signature algorithm [OkS, Ok], whose computation speed is more than twenty times faster than that of the RSA scheme, while its key length and signature length are comparable to those of the RSA scheme. This paper presents a software implementation of ESIGN on an 8bit micro-processor smart card. This realizes a computation time for signature generation of about 0.2 seconds. To achieve this remarkable speed for signature generation, appropriate implementation techniques such as pre-computation and table look-up techniques are effectively used. Moreover, this software implementation is compact enough for smart cards; the program size and the data size including the work area are at most 3Kbytes each. Practical identification schemes based on ESIGN are also presented.

The authentication of Internet of Things (IoT) devices based on the Physical Unclonable Function (PUF) is widely adopted in the information security domain. However, the leakage of PUF responses in an authentication system reduces its privacy and security. To improve its security, we can utilize the Elliptic Curve Cryptography (ECC) algorithm with different key lengths to encrypt the PUF response arbitrarily. Point multiplication is the most time-consuming operation in ECC because of its complex calculation process, which seriously affects the efficiency of the PUF response encryption. In order to solve this problem, a point multiplier based on binary field with reconfigurable key lengths of 233, 283, 409 and 571 is designed in this paper. In our method, by reusing the underlying computing units, the resources needed for point multiplication are effectively reduced. What it is more innovative is that double point multiplication operations with a key length of less than 283 bits can be performed simultaneously in the elaborate designed point multiplication circuit, which can effectively speed up the encryption process of ECC. The circuit is implemented on Xilinx Virtex-6 FPGA. The experiment results show the single point multiplication times of 233, 283, 409 and 571 key lengths are 19.33, 22.36, 41.36 and 56.5 μs, respectively, under the clock frequency of 135 MHz. In addition, it only needs 19.33 μs to perform two-point multiplication operations when the key length is 233 bits at the same time. When the key length is 283 bits, the point multiplication operation can be performed twice in 22.36 μs.

Undeniable signatures, introduced by Chaum and van Antwerpen, is a useful cryptography primitive to limit the publicly verifiable property of ordinary digital signatures. In an undeniable signature scheme, the validity or invalidity of the signature can only be verified via the confirmation/disavowal protocol with the help of the signer. An extended concept, convertible undeniable signatures, was introduced by Boyar, Chaum, Damgård and Pedersen. In the new concept, the signer can publish some selective proofs to convert one or more undeniable signatures into publicly verifiable ones, or issue a universal proof to make all his undeniable signatures publicly verifiable. In this paper, we first present a security model for convertible undeniable signature schemes, and then propose a new construction from bilinear pairings. Compared with the other schemes in the literature, the new construction has three advantages: Our scheme is both selectively and universally convertible; the signature length of our scheme is as short as BLS signature; meanwhile, all the security properties are formally proven under some conventional assumptions in the random oracle model.KeywordsUndeniable SignaturesConvertibleShort SignatureBilinear PairingsProvable Security