# BL0K: A New Stage of Privacy-Preserving Scope for Location-Based Services
## 2 Related Work
### Privacy of Zero Knowledge and Localization  
[PERSON] et al. [36] focused on LBS in a vehicular ad hoc network (VANET), where they explained the relationship between anonymity degree and expected company area, along with vehicle density. The authors then developed a privacy mechanism based on the multi-party computation and provided the cloaking region (CR) between vehicles. The scheme involves computing each vehicle based on the CR and sending it to the LBS and then returning a point of interest. The authors also added ZKP to detect the malicious vehicle. Another use of ZKP was proposed by [PERSON] et al. [37], where a novel zero-knowledge multi-copy routing algorithm with homing spread (HS) was used in mobile social networks (MSNs). The authors focused on community homes spread messages for optimally distributing a number of messages. A similar concern was addressed by [PERSON] et al. [38], where they highlighted the adversary guesses of passwords along with proposing the enhanced Kerberos protocols based on public key cryptography. However, this solution was found to require a significant amount of computation resources. As such, a new enhanced Kerberos protocol and non-interactive ZKP was introduced in the authentication process without revealing any information. [PERSON] et al. [39] applied the middleware to help generate the certificate for a client in the form of a pseudonym, which is used by a Location-Based Service Provider (LSP) at the time of seeking a service to solve the problem in the middleware under bottleneck. ZKP was adopted for authentication. [PERSON] et al. [40] proposed an anonymous authentication system. This method assigns network operator roles as an anonymous accreditation issuer for their users. However, this system supports the accreditation and is not flexible for transfer without certain security settings. This system uses the standard primitives of ZKP, message authentication codes (MAC), and Challenge-Response. [PERSON] et al. [41] suggested the combination of ZKP and RSA cryptography algorithm called Z-RSA used for the authentication in the web browser login system to prevent attacks on user passwords. Privacy-preserving data exchange algorithms are active research areas. Although recent breakthroughs such as fully homomorphic encryption (FHE) promise extremely strong privacy guarantees, such approaches are extremely inefficient at this time. Some location protection tactics, such as ZKP, are used for improving the strength or even protocols for maintaining safety regardless of the compromises. ZKP lets the participants prove any messages that are sent, which are properly produced within the procedure, are without any form of disclosure of any secret data [42]. ZKP proofs are often viewed as zk (M; N). The S in the ZKP is a section of the Boolean formula built in by using cryptography and is shown as zk: S (N\({}_{1}\) and N\({}_{\text{N}}\); M\({}_{1}\) and M\({}_{\text{M}}\)) and is even a portion of the two distinct strings of terms, whereas the holders of the location a\({}_{i}\) and b\({}_{i}\) show the relations of M\({}_{i}\) and N\({}_{i}\), correspondingly. The module in M\({}_{i}\) cannot be exposed after the instantiation of the placeholder \"S (M/a) (N/b)\", which is often revealed to be true. After this, zero-knowledge profits can then be regarded as successful. For instance, zero knowledge zk\({}_{\text{check}}\) (a\({}_{1}\); b\({}_{1}\))_a\({}_{2}\) (sign (m;k); m; vk(k)) tends to prove that the information of a signature can be successfully verified with a key vk(k) [43]. ZKP tends to vary from the traditional cryptography, where they tend to authenticate and secure the privacy of communication in contemporary applications such as LBS. The numerous benefits of ZKP often supercede the embryonic techniques of security and confidentiality since they can confirm a particular user and still ensure that the user is unidentified [44].