# Blockchain Based Trust Model Using Tendermint in Vehicular Adhoc Networks
## 2 Related Work  
### Byzantine Consensus  
The consensus is a part of distributed computing. An agreement is reached between a distributed number of processes [5], and a popular consensus scheme is called Byzantine fault tolerance (BFT). This type of protocol is used to secure the network from node failure. Practical Byzantine fault tolerance (PBFT) [7] is one of the more well-established BFT algorithms since it is based on three rounds prior to the actual agreement. This ensures that 3\(\ell\)+1 nodes are necessary to reach a consensus if we have f Byzantine nodes [7]. In [15], the author discusses well-known families of consensus algorithms for both permissionless and permissioned blockchains, which include proof of work (PoW), proof of stake (PoS), delegated proof of stake (DPoS), proof of burn (PoB), etc. Next generation deployment has carried out and the quality of services (QoS) has been discussed [34]. QoS plays very important role in the vehicular networks which defines how much efficient is the network which is presented [35]. It consists of packet delivery ratio, end to end delay and the throughput has also been discussed in results analysis [36; 37; 38; 39]. The self-mining process consumes much amount of power as described [40]. The decentralized key management mechanism has been proposed, which is a lightweight mutual authentication scheme used to prevent many network attacks [41]. Blockchain architecture is used to prevent many network attacks due to its tamperproof environment, and it provides more security to transactions. Moreover, these transactions are transparent on blockchain [42; 43].  
The distributed consensus in the blockchain creates trust between multiple parties and is referred to as Byzantine consensus [21]. Byzantine consensus is still a research field and is backed by recent advances in blockchain technology. The consensus is broadly divided into proof-based and voting-based. In the proof-based category, bitcoin is the popular one that uses PoW, which requires the miner to solve a difficult problem, and it requires a large number of resources. Moreover, the transactions are very slow, at nearly seven transactions per second. PoS uses stake to determine the mining difficulty, which can be determined as proof for the voting [21]. The proof-based mechanism provides consistency in the network, but suffers from the lower transaction rate and large resource consumption. The novel VANET system model using edge computing is implemented, and it uses an individual session key for each vehicle to prevent interference [39; 42]. The RFID-based mechanism provides better authentication and prevents many network attacks, and it uses elliptic curve cryptography to secure the session [37]. Moreover, the Telecare medical information system also used the ECC mechanism for preserving the anonymity of the user, and this has been found to be suitable in cryptography [38]. Even to secure the localization, the same trust-based mechanism is used in a wireless sensors network, which is based on decentralization [44].  
The voting-based consensus is more useful for the permissioned blockchain customer, because knowing your customer's methodology nodes will help achieve a consensus over multiple rounds of collective voting. The popular project Hyperledger fabric [27] uses PBFT in its 0.6 version, and R3 Corda employs BFT-SMaRt [28], which is identical to PBFT.