# A Survey of Internet of Things (IoT) Authentication Schemes +
## 5 Analysis of IoT Authentication Schemes
### Vehicular Networks  
Cars nowadays are connected to the Internet or the Internet of Things to form what is called vehicular networks or Internet of Vehicles. Such connectivity is used to provide different services: providing traffic information for users, sharing riding services, charging electrical cars, etc. The field of Electrical Vehicles (EV) is becoming a trend and vehicle authentication is a challenging topic in EV systems. The authors of [89] proposed a two-factor authentication scheme for EV, although it can be deployed in different fields. The scheme combines unique contextual feature. The vehicle is connected to the server via a wireless connectivity and to the charger via a charging cable, so it depends to the physical connectivity to verify the identity. The authors of [90] proposed an authentication protocol referred to as distributed aggregate privacy-preserving authentication (DAPPA) that can be used to authenticate a vehicle system with the use of multiple trusted authority one-time identity-based aggregate signature technique. A vehicle can verify many messages at the same time, and their signatures can be aggregated into a one message, which decreases the storage space needed by a vehicle or a data collector. In addition, in [91], the authors proposed a protocol to authenticate communication in secure vehicular ad-hoc networks (VANETs) using identity-based aggregate signatures. In [92], the authors provided a broadcast authentication scheme called Prediction-Based Authentication (PBA) that defends against DoS attacks and resists packet loss. The protocol is based on Merkle hash tree construction for instant verification of urgent messages, and self-generated Message Authentication Code (MAC) storage instead of storing all the receiving signatures. As an enhancement to the scheme in [92], the authors of [93] provided a Prediction-Based Authentication (PBA) as a broadcast authentication scheme in VANETs. The proposed scheme utilizes both the Elliptic Curve Digital Signature Algorithm (ECDSA) signatures and Time Efficient Stream Loss Tolerant Authentication (TESLA) to authenticate messages between vehicles which proved to be an efficient, effective, and authentication scheme. In [94], an enhancement to Dual Authentication and Key Management Techniques in VANETs is proposed, by providing an authentication phase the first time the vehicle enters the network and a re-authentication phase when the vehicle moves from one coverage area to another without the need to re-iterating the entire verification process. The authors of [95] provided a mutual authentication between vehicles using a Challenge Handshake Authentication Protocol (CHAP) that achieves both authentication and authorization, thus allowing vehicle-to-vehicle (V2V) charging using a converter-cable assembly. The authors of [96] proposed an authentication protocol for securing VANETs called (ESPA). The protocol uses asymmetric cryptography (PKI) and the symmetric HMAC for vehicle-to-infrastructure (V2I) and vehicle-to-vehicle (V2V) communications. In [97], the authors proposed a new model for authentication in VANETs based on group authentication. Vehicles are grouped and a session key is generated to be used for V2V communication. The authors of [98; 99] proposed a threshold authentication protocol to support secure and privacy-preserving communications in VANETs. The protocol is described by the use of a group signature scheme for achieving threshold authentication, efficient cancellation, anonymity, and traceability during the communication of vehicles. In [100], the authors used PKI to certify both the public key and a list of fixed unchangeable attributes of the vehicle. In [101], the authors proposed a scheme to prove the identity of one vehicle driver in to another during communication. Elliptic-curve cryptography (ECC) and steganography techniques are used for the authentication and privacy preservation of users.