Identity-based Solution Research Articles

The Review and Comparison between Centralized and Decentralized Digital Identity Systems

The growing capability of the digital world empowers physical objects to possess much more digital assets than they ever had, and the concepts of the Internet of Things and the Industrial Internet are coming out continually. Digital identity, a unique mark of two-way mapping, dynamic interaction between physical and virtual objects, is one of the fundamental elements among these novel concepts because it is the only way to distinguish each other from hundreds of millions of digital objects. In order to create a world with everything connected on the Internet, plenty of digital identity-orientated systems were raised, and new frameworks are emerging iteratively. To the best of our knowledge, this review lists some of the most applicable digital identity-based solutions by giving mechanism, digital identity solution, feature, and comparison between these models.

On the spectrum around numerical solutions in Siegel gauge in open string field theory

Abstract In bosonic open string field theory, the spectrum around the numerical tachyon vacuum solution in Siegel gauge was investigated by Giusto and Imbimbo. Using their numerical method, we study the mass spectrum around two other solutions, which are “double brane” and “single brane” solutions in Siegel gauge constructed by the level truncation approximation. The “double brane” solution was constructed by Kudrna and Schnabl and its energy might correspond to a double brane. On the other hand, the “single brane” solution was constructed by Takahashi and the author in the theory around the identity-based solution for the tachyon vacuum and its energy corresponds to the perturbative vacuum, namely, a single brane. From the eigenvalues of the matrix for the kinetic term in Siegel gauge, we find a tachyon state and a massless vector state in the ghost number g = 1 sector around the “single brane” solution, which is consistent with the perturbative vacuum, although the mass spectrum around the “double brane” solution is obscure up to truncation level L = 10 and within scalar and vector states.

A Relational Identity-Based Solution to Group Polarization: Can Priming Parental Identity Reduce the Partisan Gap in Attitudes Toward the COVID-19 Pandemic.

This study explores the influence of both group identity (e.g., partisan identity) and relational identity (e.g., parental identity) on beliefs and attitudes toward the coronavirus disease 2019 (COVID-19) pandemic. Results from a between-subject randomized survey experiment suggest that partisans are motivated to process factual information about COVID-19 through a partisan lens. However, priming parental identity can reduce partisan polarization over risk perceptions, policy support, and precautious behaviors. These findings demonstrate the need to incorporate relational identity into identity-based science communication research and offer a relational identity-based strategic communication solution to partisan gaps in responses to COVID-19.

Numerical twist-even SU(1,1)-singlet solutions in open string field theory around the identity-based solution

Using the level truncation method, we construct numerical solutions, which are twist even and SU(1) singlet, in the theory around the Takahashi-Tanimoto identity-based solution (TT solution) with a real parameter a in the framework of bosonic open string field theory. We find solutions corresponding to “double brane” and “ghost brane” solutions which were constructed by Kudrna and Schnabl in the conventional theory around the perturbative vacuum. Our solutions show somewhat similar a-dependence to tachyon vacuum and single brane solutions, which we found in the earlier works. In this sense, we might be able to expect that they are consistent with the conventional interpretation of a-dependence of the TT solution. We observe that numerical complex solutions at low levels become real ones at higher levels for some region of the parameter a. However, these real solutions do not so improve interpretation for double brane.

Continuous Virasoro algebra in open string field theory

It is known that the Takahashi-Tanimoto identity-based solution in open string field theory derives a kinetic operator which is a sum of twisted Virasoro generators. Applying the infinite circumstance description of conformal field theory, we derive continuous Virasoro algebra associated with the kinetic operator. Mode expansions of Virasoro generators and the modified BRST charge are given.

Closed string symmetries in open string field theory: tachyon vacuum as sine-square deformation

We revisit the identity-based solutions for tachyon condensation in open bosonic string field theory (SFT) from the viewpoint of the sine-square deformation (SSD). The string Hamiltonian derived from the simplest solution includes the sine-square factor, which is the same as that of an open system with SSD in the context of condensed matter physics. We show that the open string system with SSD or its generalization exhibits decoupling of the left and right moving modes and so it behaves like a system with a periodic boundary condition. With a method developed by Ishibashi and Tada, we construct pairs of Virasoro generators in this system, which represent symmetries for a closed string system. Moreover, we find that the modified BRST operator in the open SFT at the identity-based tachyon vacuum decomposes to holomorphic and antiholomorphic parts, and these reflect closed string symmetries in the open SFT. On the basis of SSD and these decomposed operators, we construct holomorphic and antiholomorphic continuous Virasoro algebras at the tachyon vacuum. These results imply that it is possible to formulate a pure closed string theory in terms of the open SFT at the identity-based tachyon vacuum.

A certificateless approach to onion routing

Onion routing protocols allow users to establish anonymous channels to preserve their privacy over a public network. Several protocols implementing this primitive have been proposed in recent years, and The onion routing network (Tor), a real-life implementation, provides an onion routing service to thousands of users over the Internet. This paper presents Certificateless Onion Routing a new approach to the problem. Starting from the identity-based solution (PB-OR) of Kate et al. (ACM TISSEC 2000), we adopt the certificateless setting introduced by Al-Riyami and Paterson in 2003. Such a setting is particularly well suited in practice as it retains the good aspects of identity-based cryptography (no PKI is required) and traditional public key cryptography (there is no key escrow). Next, we present a novel certificateless key-encapsulation mechanism and we show how to turn it into a very efficient (and provably secure!) certificateless onion routing protocol. When compared with Tor and PB-OR, our protocol offers better performances, especially when current security levels (i.e., 128 bits) are considered. In particular, our scheme significantly improves the computational costs required from each router. In this sense, our solution is up to 7 times faster than PB-OR and up to 11 times faster than Tor.

Comments on Takahashi-Tanimoto’s scalar solution

We study the identity-based solution of Witten's cubic bosonic open string field theory constructed by Takahashi and Tanimoto, which is claimed to describe the tachyon vacuum. We argue that the observables of the solution coincide with those of the tachyon vacuum using the method proposed by Kishimoto and Takahashi. We also discuss how to treat the kinetic term of the string field theory expanded around it.

New approach to vacuum string field theory

We discuss the possibility of applying a purely ghost kinetic operator in open string field theory from the perspective of a modern analytic method based on the KBc subalgebra. A purely ghost kinetic operator is obtained as a result of gauge fixing string field theory around the identity-based tachyon vacuum solution. We show that the obtained kinetic operator is not equivalent to the midpoint insertion of a conformal ghost, to which an extensive literature is devoted. We also show that the equation of motion does not admit nontrivial solutions.

A simple solution for marginal deformations in open string field theory

We derive a new open string field theory solution for boundary marginal deformations generated by chiral currents with singular self-OPE. The solution is algebraically identical to the Kiermaier-Okawa-Soler solution and it is gauge equivalent to the TakahashiTanimoto identity-based solution. It is wedge-based and we can analytically evaluate the Ellwood invariant and the action, reproducing the expected results from BCFT. By studying the isomorphism between the states of the initial and final background a dual derivation of the Ellwood invariant is also obtained.

Gauge invariant overlaps for identity-based marginal solutions

We investigate identity-based solutions associated with marginal deformations in open string field theory. We find that the identity-based marginal solutions can be represented as a difference of wedge-based solutions plus an integration of a deformed Becchi-Rouet-Stora-Tyutin exact state. Using this expression, the gauge invariant overlap can be calculated analytically for the identity-based solutions. Moreover, we show that, by gauge transformation, the overlap is transformed into a disk correlation function with the integrations of currents at the boundary.

Tachyon vacuum of bosonic open string field theory in marginally deformed backgrounds

We consider bosonic open string field theory in marginally deformed backgrounds, which is obtained by expanding the string field around the identity-based solutions associated with marginal deformations. We find a new set of string fields which satisfies the KBc algebra, but the nilpotent kinetic operator is that of the theory expanded around the identity-based marginal solution. By use of these string fields, we construct the tachyon vaccum solution in marginally deformed backgrounds. The vacuum energy density is equivalent to that of the tachyon vacuum without marginal deformations. The gauge invariant overlap is changed according to the effect of marginal deformations, as expected from known results in CFT. These results suggest that the vacuum energy is zero for the identity-based marginal solutions in the original theory.

ONE-LOOP VACUUM ENERGY AT THE TACHYON VACUUM

We consider one-loop vacuum energy at the tachyon vacuum in cubic bosonic open string field theory. The BRST operator Ql in the theory around an identity-based solution is believed to represent a kinetic operator at the tachyon vacuum. Using homotopy operators for Ql, we find that one-loop vacuum energy at the tachyon vacuum is independent of moduli such as interbrane distances. This result can be interpreted as support for the annihilation of D-branes at the tachyon vacuum even in the quantum theory.

Homotopy Operators and One-Loop Vacuum Energy at the Tachyon Vacuum

We construct the homotopy operators for the BRST operator in the theory around the identity-based solutions, which are believed to represent the tachyon vacuum in cubic bosonic open string field theory. Using the homotopy operators, we find that the one-loop vacuum energy at the tachyon vacuum is independent of moduli such as interbrane distances, which are included in the BRST operator. We also revisit the cohomology problem, which was solved earlier without the homotopy operators.

Homotopy operators and identity-based solutions in cubic superstring field theory

We construct a class of nilpotent operators using the BRST current and ghost fields in superstring theory. The operator can be realized in cubic superstring field theory as a kinetic operator in the background of an identity-based solution. For a particular type of the deformed BRST operators, we find a homotopy operator and discuss its relationship to the cohomology in a similar way to the bosonic case, which has been elaborated by the authors.

A Vacuum Loop of an Open String around an Identity-Based Solution

Bosonic Open String field theory has classical solutions describing a tachyon vacuum where D-branes completely annihilate. First, a numerical solution was constructed by using level truncation approximation in the Siegel gauge.1),2) Then, analytic classical solutions were constructed in terms of an identity string field∗) or wedge-like states.4) Although there are some differences, it is thought that these types of solutions possess certain properties of the tachyon vacuum: its vacuum energy density cancels a D-brane tension and the kinetic operator on its vacuum has vanishing cohomology.6),7) This makes us believe that these solutions correspond to the tachyon vacuum, but an important problem remains unsolved. How can we find closed strings on the vacuum? It has been noted that the identity-based solution provides the possibility of understanding closed strings on the vacuum. In the theory expanded around the identity-based solution, we can construct a Siegel gauge propagator acting on the usual open string Fock space. As pointed out by Drukker, the propagator generates a worldsheet swept by an open string, but the boundary is fixed at a point in the case of the tachyon vacuum solution.8) Hence, an amplitude calculated by the propagator corresponds to a worldsheet without boundaries, that is a closed string surface generated by closed strings. This closed worldsheet picture around the identity-based solution provides fascinating possibility to find closed strings of the tachyon vacuum. However, we encounter divergence difficulties if we calculate the amplitude explicitly. In this talk, we regularize this divergent amplitude by using level truncation approximation in order to explore the possibility of finding closed strings of the tachyon vacuum. In §2, we will give a brief review on the identity-based solution. In §3, we will provide a vacuum loop amplitude of an open string in the expanded theory. Finally, we will give concluding remarks in §4. This talk is based on the work in collaboration with S. Inatomi, I. Kishimoto and Y. Saito.

Efficient and Identity-based Signcryption with Provably-secure

The idea of signcryption is to provide a method to encrypt and sign data together, so it is more efficient than using an encryption scheme combined with a signature scheme. We present an identitybased signcryption solution, which is one of the most efficient, provably-secure schemes proposed to date. Our scheme admits provable security in the random oracle model under the bilinear DiffieHellman assumption using the definitions proposed by Boyen and it is also forward secure.

Generating Erler–Schnabl-type solution for the tachyon vacuum in cubic superstring field theory

We study a new set of identity-based solutions to analyze the problem of tachyon condensation in open bosonic string field theory and cubic superstring field theory. Even though these identity-based solutions seem to be trivial, it turns out that after performing a suitable gauge transformation, we are left with the known Erler–Schnabl-type solutions which correctly reproduce the value of the D-brane tension. This result shows explicitly that a seemingly trivial solution can generate a non-trivial configuration which precisely represents the tachyon vacuum.

Exploring the vacuum structure near identity-based solutions

We explore the vacuum structure in the bosonic open string field theory expanded near an identity-based solution parameterized by a (≥ −1/2). Analyzing the expanded theory using the level-truncation approximation up to the level 20, we find that the theory has the tachyon vacuum solution for a ≥ −1/2. We also find that at a = −1/2, there exists an unstable vacuum solution in the expanded theory and the solution is expected to be the perturbative open string vacuum. These results reasonably support the hypothesis that the identity-based solution is a trivial pure gauge configuration for a > −1/2, but it can be regarded as the tachyon vacuum solution at a = −1/2.

Vacuum Structure around Identity-Based Solutions

We explore vacuum structure in bosonic open string field theory expanded around an identity based solution parameterized by $a$ (>= -1/2). Analyzing the expanded theory by using level truncation approximation up to level 14, we find that the theory has a stable vacuum solution for $a$>-1/2. The vacuum energy and the gauge invariant overlap numerically approach those of the tachyon vacuum solution with increasing truncation level. Also we find that, at $a$=-1/2, there exists an unstable vacuum solution in the expanded theory and it rapidly becomes the trivial zero configuration just above $a$=-1/2. The numerical behavior of the two gauge invariants suggests that the unstable solution corresponds to the perturbative open string vacuum. These results reasonably support the expectation that the identity based solution is a trivial pure gauge configuration for $a$>-1/2, but it can be regarded as the tachyon vacuum solution at $a$=-1/2.