# FHAAPS: Efficient Anonymous Authentication with Privacy Preservation Scheme for Farm-to-Home Communication

Authors: Arun Sekar Rajasekaran; M. Azees; Khalid Yahya
Journal: Security and Communication Networks
 (2023)

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## Abstract

With the advancement in information and communication technology (ICT), secure farm-to-home communication has become an emerging concept. Food is the most basic essential commodity for the survival of human beings which is produced by farmers. However, because of the presence of intermediaries, farmers/producers do not make a sufficient profit and also the consumers have to pay more money to buy food items from these mediators. As a result, in this work, we proposed an efficient farm-to-home anonymous authentication privacy-preserving scheme in which the storehouse will buy goods from farmers and sell them to the consumers at the base rate. Moreover, in our scheme, an unprofitable trusted delivery agent assists in the transfer of food commodities between end users and storehouses to provide maximum profit for the farmers and consumers. Further, essential security parameters are provided to the end users and it provides conditional privacy to the delivery agent; i.e., if any mishap occurs, then the malicious delivery agent’s privacy is revoked to avoid further damage to the system. The performance analysis section shows that our scheme supports the transfer of food commodities with minimum computational and communication costs.


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## Body

## 1. Introduction

Food cultivation becomes essential for the survival of human beings around the globe. Farmers are the primary cultivators of food crops. They play an important role in society, as they provide food to human beings through agriculture. However, the presence of the mediators has an impact on their agricultural income. Moreover, the agreement restrictions prevent the majority of the farmers from benefiting from it. If the trade prices fall just below the minimum support price (MSP), farmers will receive cost shortfall payouts under the agreement system. The profiting intermediaries are the main impediment to boosting the farmer’s revenue. Market intermediaries, merchants, and distributors take a large portion of the earnings from farmer production. Moreover, the intermediaries act like an in-charge of the market, which will affect both the customer and the farmer. As a result, farmers will not receive adequate profit for their subsequent crops, resulting in debt. Even some farmers commit suicide because of their indebtedness and reduced revenue.So, we introduced the concept of eliminating the intermediaries and establishing communication between the farmers and the consumer known as a Farm-to-Home Anonymous Authentication with Privacy Preservation Scheme (FHAAPS). It is a web-based customer service platform. It has become a convincing and widely accepted commercial standard for buyers and sellers to communicate and engage in the purchasing process. As a result, the main organisation is housed in server space, whereas the sub-branches are housed in distinct places. The information from the sub-branches will be transferred to the authenticated users of the specific location. Online communication of information for any online service may be vulnerable to malicious attacks. Unless adequate security practices [1] are to be implemented, the users could be subject to a variety of assaults, namely, replication attacks and bogus information attacks. The most important security factor to prevent these attacks and perform secure data transactions is authentication. If users are not provided with authentication, a malicious user could mislead the data in the trusted farm-to-home (TFH) platform. Here, TFH may not act as a profitable middleman, but act as a link between the farmer and the consumer.To ensure secure communication [2], an unprofitable centralized main branch generates a fully authenticated TFH in different locations offline. Initially, authenticated TFH provides authentication parameters to the end entities (farmers/consumers) through offline registration. These authentication parameters [3] increase the trust between the entities and the TFH. The keys generated by TFH are used to verify the data communication authenticity. Only verified users can get access to message their requirements through the specific application provided by the TFH. Moreover, the scheme will be a popular way for purchasers to purchase goods and a handy platform for the farmers to improve their revenues. In addition, it transforms into a two-way profitable platform by which both the consumer and farmer get benefitted. In the existing system, even though user authentication is provided [4, 5], there may be a chance of identity theft of the user, resulting in a loss of privacy and protection for entities. Some malevolent users can gain access to the network of authenticated users by stealing information from authorised users. There are some protection solutions that prohibit fraudulent individuals from gaining access to the network. But they require a significant amount of computing time, and there is a risk that the user’s real identity would be revealed using these approaches [6, 7]. So in this proposed scheme, we provide anonymous authentication by using dummy identities of entities to provide service for the end users, which takes less computational and verification cost.Data integrity is a critical security component [8–10]. The farm-to-home (FH) main branch is a trusted element that preserves data and monitors the TFH, which in turn monitors the end entities. Moreover, the basic security criteria such as privacy, confidentiality, integrity, and availability are met in our scheme. To achieve long-term trading communications between end users and TFH, a straightforward privacy revocation mechanism and reliable anonymous authentication with little complexity are proposed to sustain end-user entity communication. The scheme is developed in order to meet the following critical security standards:(i)
End users obtain anonymous authentication keys at the time of initial offline registration, which is stored separately in the TFH database to protect their privacy(ii)
If any attack happens, the TFH will trace the fraudulent person’s identity and broadcast it to all the authenticated users and also revoke them from the network(iii)
It provides end users with robust data protection and privacy


### 1.1. Our Research Contributions

The suggested approach's main contributions to enhance the aforementioned security standards are as follows:(i)
To reduce the risk of data loss when transferring information from TFH to end users (either farmers or customers) or vice versa(ii)
To design an authentication scheme for the end users with less computation complexity which provides anonymity and conditional privacy(iii)
To provide the user’s data integrity with minimum signature and certificate verification cost(iv)
-To provide conditional privacy to all entities in the system by using conditional tracking to trace the real identities of all compromised entitiesThe following is a summary of the rest of the article: In the next section, related works are explained. The overview of the system is explained in Section3. In Section 4 the proposed methodology of our approach is discussed. The proposed approach to security and performance analysis is addressed in Sections 5 and 6. Finally, Section 7 concludes the work.


## 1.1. Our Research Contributions

The suggested approach's main contributions to enhance the aforementioned security standards are as follows:(i)
To reduce the risk of data loss when transferring information from TFH to end users (either farmers or customers) or vice versa(ii)
To design an authentication scheme for the end users with less computation complexity which provides anonymity and conditional privacy(iii)
To provide the user’s data integrity with minimum signature and certificate verification cost(iv)
-To provide conditional privacy to all entities in the system by using conditional tracking to trace the real identities of all compromised entitiesThe following is a summary of the rest of the article: In the next section, related works are explained. The overview of the system is explained in Section3. In Section 4 the proposed methodology of our approach is discussed. The proposed approach to security and performance analysis is addressed in Sections 5 and 6. Finally, Section 7 concludes the work.


## 2. Related Works

In recent years, online trading has attracted several end users due to the massive development of ICT. The existing trading is affected by a number of security issues because of the presence of mediators. Several works related to security issues are discussed in this section. León et al. [11] proposed anonymous communication in e-government services. The authors focussed on anonymous communication with the application called delta. Its function is to enable the offers and lay the groundwork for future e-government service procedures. When information is exchanged, anonymous communication is implemented through the delta application. The message integrity is not maintained in this work. Moreover, a separate communication channel is required for the transfer of information. Fouladfar [12] proposed a work that is based on the following two types of securities: soft securities and hard securities. Hard securities are related to information hiding and cryptography, whereas soft security deals with trust issues. In this work, a security graph is used for exchanging information from one to another. But, this approach is unable to detect the real identity of the malevolent users. Almuzairai et al. [13] proposed a privacy protection scheme for users of e-commerce systems. In this work, the importance of digitalized services is focussed. Through these online services, the user shares their personal data in e-commerce trading. Since it is open source, it is easy for an attacker to interrupt the user’s data.Liu et al. [14] proposed a blockchain-based autonomous transaction settlement system for IoT-basede-commerce. The system proposed a normal chain with three layered blockchain networks which can improve the efficiency of the transaction and the stability of the system. Though this work has provided security in an advanced way, the computational cost of this approach is high and the system is to be upgraded frequently with respect to technology. Aitzhan et al. [15] proposed a decentralized energy trading model through multisignatures, blockchain, and anonymous messaging streams. In this work, the current financial infrastructures are centralised, implying that a trusted third party is involved which handles the payments and security. Though peer-to-peer communication can be done through data replication methods, there are scalability issues in this work. Wang et al. [16] work on the evaluation method for e-commerce transaction systems with unobservable transactions. This work can be used in the analysis and design of the system for online transaction processes. However, some e-commerce systems are incompatible with this approach because they ignore data information.Zhang et al. [17] proposed a hybrid trust evaluation framework for e-commerce in online social networks. This work is based on improving trust managing mechanisms. Though it can give an accurate trustworthy view, it is not much accurate in the complex social network trading platforms. Jiang et al. [18] proposed a privacy-preserving business protocol by using private smart contracts to ensure privacy in e-commerce. This approach allows both seller and buyer to make deals without revealing their real identities such as name, address, and phone numbers. In this work, the user’s privacy is preserved, but there is no conditional tracking mechanism to revoke the privacy of a compromised entity in the system. Niu et al. [19], proposed a TPDM system to enhance the truthfulness and privacy preservation in data markets. This system is internally built in an encrypt-then-sign fashion by using homographic encryption and identity-based signature which ensures the privacy of the user’s data. Though the proposed work allows batch verification, data processing, and outcome verification. But an external attacker can forge the signature of the authorised users and they can send fake messages into the system. Moreover, this system uses profile-matching techniques which may give false results, if we compare authorised profiles with a fake profile which is created by a malicious user.In [20], Fan et al. proposed a secure mutual authentication protocol using an asymmetric cryptosystem and universal second factor (U2F) technique to ensure security in mobile payments in e-commerce platforms. This system enhances the security and privacy of user account information in the mobile payment transaction process. But, when the servers and clients are mutually authenticating each other, they will use their real identities which may lead to identity theft by malicious or compromised users. Tsobdjou et al. [21] proposed a mutual authentication protocol based on elliptical curve cryptography for communication between the server and mobile client to avoid additional hardware and to withstand impersonation attacks. Moreover, the authors have focussed on session key security, perfect forward secrecy, resistance to replay, and insider attacks. But the system cannot withstand a denial of service attack, and it may have more communication and computation overheads because of more complexity.Trade Map as an integrated architecture is proposed in [22], to enable privacy in online end-to-end marketplace transactions. Here, the authors used the FINMA-KYC platform to register and authenticate entities. Moreover, blockchain-based transactions are used to store the data by employing Ethereum smart contracts. In addition, the user data is only visible to KYC platforms in registration the phase, thereby providing anonymity to the user’s data. But, because of other KYC platform involvement, there may be a lot of communication and computation overheads in the system while identifying the legitimacy of the users. In [23], Li et al. proposed a cross-realm authentication scheme of Kerberos protocol in-home delivery services. This Kerberos protocol is applied in online ordering and offline delivery businesses to establish authenticity for all entities in the system. Though physical security is ensured, authentication of delivery men is crucial and there may be a chance of privacy leakage because of the usage of real identities. In [24], Yuniati et al. proposed a credit card payment method using visual cryptography to withstand attacks like phishing and identity theft. The authors applied visual cryptography to the captcha which is generated by the merchant during the registration phase. Though it enhances the e-payment security in terms of authorisation and confidentiality, there is a possibility for an intruder to modify the visual image, so that it cannot be decrypted appropriately at the receiver side. Further, it cannot withstand a man-in-the-middle attack.


## 3. System Overview

The system model, pairing parameters, and attack models are described in this section.


### 3.1. System Model

Trusted farm-to-home (TFH) branches, delivery agents (DA), and end users are the major components of the proposed system. Figure1 shows the system model of the farm-to-home platform. An end user can be a farmer or a consumer. The delivery agent delivers/gathers goods at the consumer/farmer location and RFID tags are incorporated in the dummy identity of the delivery agent to trace the location of him by the end user/TFH at any time. Initially, the trusted main branch installs TFH in the required areas in an offline manner.Figure 1
System model of the farm-to-home platform.


#### 3.1.1. Trusted Farm-to-Home (TFH) Platform

TFH is the main component of our proposed system. It is a trusted authority, and it is extremely impossible for an attacker to compromise the farm-to-home platform. When an end-user registers in the TFH, he will receive specific certified keys that will allow him to communicate with the TFH using a one-time password (OTP). Initially, the end users (farmers/consumers) register at TFH by submitting their credentials in the offline mode. Here, the entire communication between the TFH and the end users will be done in a safe manner. If a user requests his requirements to the TFH, the TFH will send him an OTP, to check his authenticity. Similarly, if a farmer is willing to sell the goods, he will inform TFH about the details of the goods. Then, the TFH will issue him an OTP to confirm whether he is a legitimate user or not. So, once the authenticity of the consumer/farmer is verified, only then transfer of goods takes place between the end user and TFH or vice versa.


#### 3.1.2. End Users

An end user can be a farmer or a buyer who is willing to sell or buy goods at TFH. The user’s (farmer/consumer) registration can be done in an offline manner at TFH. The end user can communicate with TFH to get service at any time. After successful offline registration, the farmer/user will be provided with definite credentials. Once the farmer logs into the producer portal with his credentials, he will be initially verified by the OTP. After successful validation, he will send the details of the commodities to a specific TFH. Similarly, consumers also login into the portal and will be initially verified by OTP. After successful verification, he sends his demand message to TFH. Based on the requirements, TFH provides the service to the end user.


#### 3.1.3. Delivering Agents (DAi)

Delivery agents are the essential entity in our proposed scheme, who provide service to the end users. Initially, the registration of the delivery agents can be done in an offline mode to their nearest TFH. When the end user contacted the TFH about his requirements, then the TFH will message to theDAi, who are working under the TFH to contact them. Then, after the arrival of DAi, TFH will check his identity and provide him with the details of the particular end user like location and dummy identity. A dummy identity is used to provide privacy to the user’s real identity thereby ensuring anonymity. Here, there may be a chance for the DAi being compromised. Hence, at the time of the registration, an RFID tag will be attached to the DAi and it will be activated at the time of delivering or carrying the products to/from the end users. After reaching the end user’s location, the user will authenticate the DAi. Only, if the DAi is an authorised agent, then the farmer will provide his goods or the consumer will receive his requested goods. The usage of RFID tags which are provided to DAi will allow TFH to monitor the progress of the delivery of the goods. Notations used in this work are shown in Table 1.Table 1
List of notations.
NotationsDescriptionTFHTrusted farm-to-homeDADelivery agentOTPOne time passwordj,kMaster secret keys of TFHK1,J1Public keys of TFHeBilinear pairingDRIIDelivery agent's real identityDADIiDelivery agent dummy identityMik,NikElements of tracking listDkDelivery agent keyPmShort-time private keysRmShort-time public keysDCKDelivery agent contender keycertjDelivery agent anonymous certificatesigDelivery agent short time signature


### 3.2. Security Attack Models

The attackers are divided into two categories in the suggested strategy. One type of attacker is an internal one, while the other is an external one. Both external and internal attackers pose a threat, but there will be a more threat from the external attacker. Internal attackers can attack the proposed system by using the keys which are given to the end users at the time of registration. If the end users are compromised, then the privacy of the compromised entity will be revoked by the TFH. But, there may be a possibility of external attackers gaining access to the valid user’s personal information and trying to change their data. So, the proposed approach is planned to avoid the influence of the following attacks from external attackers:(i)
Impersonation attack: an attack in which the attacker gets access to the authorised users and manipulates the end user’s required data.(ii)
Certificate and key duplication attack: without the assistance of the authenticated user, the malicious user can construct similar credentials of the authenticated user and access the valid end user site for their benefit.(iii)
Identity revealing attack: the focus of this attack is on the user’s privacy. Here, the intruders illegally gather the confidential information of the end users.(iv)
Fake message attack: by changing the information of the end entities, an attacker can deliver fake information to the TFH.


### 3.3. Bilinear Pairing

LetGa, Gb, and GT be the three multiplicative cyclic groups of order n. Here, n represents the large prime number. Let ga and gb belongs to the generators Ga and Gb, respectively. Moreover, δ be an isomorphism from Gb to Ga such that δgb=ga. The bilinear mapping function is represented as e:Ga×Gb⟶GT and it should obey the following properties:(i)
Bilinear:egap,gbq=ega,gbpq for all ga∈Ga, gb∈Gb, and p,q∈Zn∗(ii)
Nondegeneracy:ega,gb≠1GT(iii)
Computability: there exists an efficient algorithm to compute the bilinear mape:Ga×Gb⟶GT.


## 3.1. System Model

Trusted farm-to-home (TFH) branches, delivery agents (DA), and end users are the major components of the proposed system. Figure1 shows the system model of the farm-to-home platform. An end user can be a farmer or a consumer. The delivery agent delivers/gathers goods at the consumer/farmer location and RFID tags are incorporated in the dummy identity of the delivery agent to trace the location of him by the end user/TFH at any time. Initially, the trusted main branch installs TFH in the required areas in an offline manner.Figure 1
System model of the farm-to-home platform.


### 3.1.1. Trusted Farm-to-Home (TFH) Platform

TFH is the main component of our proposed system. It is a trusted authority, and it is extremely impossible for an attacker to compromise the farm-to-home platform. When an end-user registers in the TFH, he will receive specific certified keys that will allow him to communicate with the TFH using a one-time password (OTP). Initially, the end users (farmers/consumers) register at TFH by submitting their credentials in the offline mode. Here, the entire communication between the TFH and the end users will be done in a safe manner. If a user requests his requirements to the TFH, the TFH will send him an OTP, to check his authenticity. Similarly, if a farmer is willing to sell the goods, he will inform TFH about the details of the goods. Then, the TFH will issue him an OTP to confirm whether he is a legitimate user or not. So, once the authenticity of the consumer/farmer is verified, only then transfer of goods takes place between the end user and TFH or vice versa.


### 3.1.2. End Users

An end user can be a farmer or a buyer who is willing to sell or buy goods at TFH. The user’s (farmer/consumer) registration can be done in an offline manner at TFH. The end user can communicate with TFH to get service at any time. After successful offline registration, the farmer/user will be provided with definite credentials. Once the farmer logs into the producer portal with his credentials, he will be initially verified by the OTP. After successful validation, he will send the details of the commodities to a specific TFH. Similarly, consumers also login into the portal and will be initially verified by OTP. After successful verification, he sends his demand message to TFH. Based on the requirements, TFH provides the service to the end user.


### 3.1.3. Delivering Agents (DAi)

Delivery agents are the essential entity in our proposed scheme, who provide service to the end users. Initially, the registration of the delivery agents can be done in an offline mode to their nearest TFH. When the end user contacted the TFH about his requirements, then the TFH will message to theDAi, who are working under the TFH to contact them. Then, after the arrival of DAi, TFH will check his identity and provide him with the details of the particular end user like location and dummy identity. A dummy identity is used to provide privacy to the user’s real identity thereby ensuring anonymity. Here, there may be a chance for the DAi being compromised. Hence, at the time of the registration, an RFID tag will be attached to the DAi and it will be activated at the time of delivering or carrying the products to/from the end users. After reaching the end user’s location, the user will authenticate the DAi. Only, if the DAi is an authorised agent, then the farmer will provide his goods or the consumer will receive his requested goods. The usage of RFID tags which are provided to DAi will allow TFH to monitor the progress of the delivery of the goods. Notations used in this work are shown in Table 1.Table 1
List of notations.
NotationsDescriptionTFHTrusted farm-to-homeDADelivery agentOTPOne time passwordj,kMaster secret keys of TFHK1,J1Public keys of TFHeBilinear pairingDRIIDelivery agent's real identityDADIiDelivery agent dummy identityMik,NikElements of tracking listDkDelivery agent keyPmShort-time private keysRmShort-time public keysDCKDelivery agent contender keycertjDelivery agent anonymous certificatesigDelivery agent short time signature


## 3.1.1. Trusted Farm-to-Home (TFH) Platform

TFH is the main component of our proposed system. It is a trusted authority, and it is extremely impossible for an attacker to compromise the farm-to-home platform. When an end-user registers in the TFH, he will receive specific certified keys that will allow him to communicate with the TFH using a one-time password (OTP). Initially, the end users (farmers/consumers) register at TFH by submitting their credentials in the offline mode. Here, the entire communication between the TFH and the end users will be done in a safe manner. If a user requests his requirements to the TFH, the TFH will send him an OTP, to check his authenticity. Similarly, if a farmer is willing to sell the goods, he will inform TFH about the details of the goods. Then, the TFH will issue him an OTP to confirm whether he is a legitimate user or not. So, once the authenticity of the consumer/farmer is verified, only then transfer of goods takes place between the end user and TFH or vice versa.


## 3.1.2. End Users

An end user can be a farmer or a buyer who is willing to sell or buy goods at TFH. The user’s (farmer/consumer) registration can be done in an offline manner at TFH. The end user can communicate with TFH to get service at any time. After successful offline registration, the farmer/user will be provided with definite credentials. Once the farmer logs into the producer portal with his credentials, he will be initially verified by the OTP. After successful validation, he will send the details of the commodities to a specific TFH. Similarly, consumers also login into the portal and will be initially verified by OTP. After successful verification, he sends his demand message to TFH. Based on the requirements, TFH provides the service to the end user.


## 3.1.3. Delivering Agents (DAi)

Delivery agents are the essential entity in our proposed scheme, who provide service to the end users. Initially, the registration of the delivery agents can be done in an offline mode to their nearest TFH. When the end user contacted the TFH about his requirements, then the TFH will message to theDAi, who are working under the TFH to contact them. Then, after the arrival of DAi, TFH will check his identity and provide him with the details of the particular end user like location and dummy identity. A dummy identity is used to provide privacy to the user’s real identity thereby ensuring anonymity. Here, there may be a chance for the DAi being compromised. Hence, at the time of the registration, an RFID tag will be attached to the DAi and it will be activated at the time of delivering or carrying the products to/from the end users. After reaching the end user’s location, the user will authenticate the DAi. Only, if the DAi is an authorised agent, then the farmer will provide his goods or the consumer will receive his requested goods. The usage of RFID tags which are provided to DAi will allow TFH to monitor the progress of the delivery of the goods. Notations used in this work are shown in Table 1.Table 1
List of notations.
NotationsDescriptionTFHTrusted farm-to-homeDADelivery agentOTPOne time passwordj,kMaster secret keys of TFHK1,J1Public keys of TFHeBilinear pairingDRIIDelivery agent's real identityDADIiDelivery agent dummy identityMik,NikElements of tracking listDkDelivery agent keyPmShort-time private keysRmShort-time public keysDCKDelivery agent contender keycertjDelivery agent anonymous certificatesigDelivery agent short time signature


## 3.2. Security Attack Models

The attackers are divided into two categories in the suggested strategy. One type of attacker is an internal one, while the other is an external one. Both external and internal attackers pose a threat, but there will be a more threat from the external attacker. Internal attackers can attack the proposed system by using the keys which are given to the end users at the time of registration. If the end users are compromised, then the privacy of the compromised entity will be revoked by the TFH. But, there may be a possibility of external attackers gaining access to the valid user’s personal information and trying to change their data. So, the proposed approach is planned to avoid the influence of the following attacks from external attackers:(i)
Impersonation attack: an attack in which the attacker gets access to the authorised users and manipulates the end user’s required data.(ii)
Certificate and key duplication attack: without the assistance of the authenticated user, the malicious user can construct similar credentials of the authenticated user and access the valid end user site for their benefit.(iii)
Identity revealing attack: the focus of this attack is on the user’s privacy. Here, the intruders illegally gather the confidential information of the end users.(iv)
Fake message attack: by changing the information of the end entities, an attacker can deliver fake information to the TFH.


## 3.3. Bilinear Pairing

LetGa, Gb, and GT be the three multiplicative cyclic groups of order n. Here, n represents the large prime number. Let ga and gb belongs to the generators Ga and Gb, respectively. Moreover, δ be an isomorphism from Gb to Ga such that δgb=ga. The bilinear mapping function is represented as e:Ga×Gb⟶GT and it should obey the following properties:(i)
Bilinear:egap,gbq=ega,gbpq for all ga∈Ga, gb∈Gb, and p,q∈Zn∗(ii)
Nondegeneracy:ega,gb≠1GT(iii)
Computability: there exists an efficient algorithm to compute the bilinear mape:Ga×Gb⟶GT.


## 4. Proposed FHAAPS

In this section, the system initialization and delivery agent’s authentication processes are described. Initially, end users and delivery agents should register in the TFH platform with their credentials through offline mode. After successful registration, the TFH provides the required credentials to the end user and delivery agent. If the end user (farmers/consumers) wishes to sell or buy a commodity, he must send his sale/demand message to TFH through the specific application. Once the username and password are successfully entered into the application, the end users receive an OTP (one-time password). Once the OTP is entered, the end users are allowed to send their sale/demand message to TFH. After receiving the message information, the TFH assigns this task (buying/delivering farm goods) to the nearby authenticated delivery agent. Once the message is received, the delivery agent performs the specific task assigned to them. Here, the delivery agent should be authenticated by the end user. Once the delivery agent is authenticated, the end user (farmer/consumer) may send/receive the agricultural goods to/from the TFH through the delivery agent. Here, the message integrity and legitimacy are performed by bilinear pairing.


### 4.1. System Initialization

The TFH issues system parameters by using the bilinear parametersGa,Gb,p,e as follows: Initially, the TFH selects the random numbers j,k∈Zp∗ as the master secret keys and computes K1=gak and J1=gaj. Then, TFH selects the secure cryptographic hash function H:0,1∗⟶Zp∗. Finally, the TFH issues the FH parameters and broadcasts in the open network platform as FHparam=Ga,Gb,p,ga,gb,K1,J1,H,e.


### 4.2. Delivery AgentDAi Authentication by End Users

In our proposed scheme, the delivery agent authentication process consists ofDAi registration, required keys generation, generation of anonymous certificate and signature, verification of both certificate and signature, and conditional tracking.


#### 4.2.1.DAi Registration

Initially,DAi should register in TFH through offline mode. During initial offline registration, the Delivery agent DAi have to submit the necessary information such as user name, address, mail ID, and phone number to the TFH. Once the registration process is successfully completed, the TFH provides credentials to the DAi.


#### 4.2.2. Key Generation

AfterDAi registration, the TFH generates the necessary secret keys for the DAi by using a key generation scheme. Initially, the TFH generates the delivery agent’s DAi real identity DRII and also dummy identity DADIi. This DADIi is in-build with an RFID tag. To generate a dummy identity DADIi, the TFH uses two random numbers fi,hi∈Zp∗ and then computes DADIi = gaj+k+fi. Then, the TFH maps the original identity with a dummy identity. Moreover, the TFH creates dummy identities for all delivery agents to check the legitimacy and integrity of the source of information and to track the movement of DAi. Then, the TFH selects random numbers hi and fi such that hi,fi∈Zp∗ and computes Mi = ga1/hi+k+fi and Ni = gak+j+hi for tracking the identity of DAi. Then, TFH places these values DARIi,DADIi,Mik,Nik in the tracking list and issues the delivery agent key Dk to DAi as Dk=DADIi,Mik,Nik,Pi,Qi and this Dk will be kept securely by the delivery agent, where Pi = ga−j+fi and Qi = ga−hi+k. Once the registration and key distribution process is completed, the delivery agent DAi become the authenticated agent for delivering/getting the commodities to/from the end users (farmers/consumers).


#### 4.2.3. Anonymous Certificate Generation

The delivery agentDAi perform the following steps to generate the required anonymous certificates.Step 1.
Initially theDAi choose random numbers P1,P2,P3,…,Pr∈Zp∗, where r≤p as short time temporary private keys and computes the short time public keys Rm = gbPm for m=1,2..r.Step 2.
Then, theDAi generate the anonymous one-time certificate certj by using their short-time public keys Rm as follows:
Initially, theDAi randomly selects t1,t2,t3,t4∈Zp∗ and calculates μ1,μ2,μ3,∅1,∅2,∅3, where(1)μ1=K1t1+t2,μ2=MiJ1t1+t2,μ3=NiK1t1+t2,∅1=μ1t1+t2+μ2t3+t4,∅2=μ2t1+t2−μ3t3+t4,∅3=μ1t1+t2.μ2t3+t4μ3t1+t4.
After computingμ1,μ2,μ3,∅1,∅2,∅3, the DAi calculates the delivery agent contender key DCK=HDDIi∥J1∥K1∥Pi∥μ1∥μ2∥μ3∥∅1∥∅2∥∅3∥Rm and then compute the values of θ1,θ2,θ3 and θ4 as below θ1=t1−Pm, θ2=t2+Pm, θ3=t3−Pm, θ4=t4+Pm
Finally, theDAi will generate the anonymous certificate as certj=DADIi∥Rm∥Pi∥Qi∥DCK∥μ1∥μ2∥μ3∥Ni∥θ1∥θ2∥θ3∥θ4.(i)
Signature generation: theDAi generate the short-time signature as sig=ga1/Pm+HCM to maintain the integrity of the message. Then, the DAi broadcasts the message as message=CM∥sig∥certj∥Rm by appending the certificate, signature, and short-time public key. From the received message, the end user extracts the values of DADIi,Pi,Qi,Ni. Moreover, the end-user computes Hi=DADIi×Pi, Di=Ni×Qi, and check whether Hi=K1andDi=J1. If they are equal, then the end user accepts the DAi as an authorised DAi. Initially, the delivery agent sends this message to the end user while communicating with them. The end user authenticates the delivery agent and verifies the integrity of the message. Once the verification is completed, the end user allows the delivery agent to perform their specific function; i.e., the delivery agent (DAi authentication by the end user. Here, the end user (farmer/consumer) will authenticate the delivery agent by using DAi’s certificate Cerj and signature sig by following the verification process.(ii)
Verification process: after receiving theMessage=CM∥sig∥certj∥Rm from the delivery agent, the end user (farmer/consumer) will perform the following steps to authenticate the delivery agent.Step 1: To check the authenticity of the source message, the receiver will calculateHi,Ii,β1′,β2′,β3′ parameters, where(2)Hi=DADIi×Pi,Di=Ni×Qi,∅1′=μ1θ1+θ2+μ2θ3+θ4,∅2′=μ2θ1+θ2−μ3θ3+θ4,∅3′=μ1μ3θ1μ2μ3θ4.μ1θ2.μ2θ3.Step 2: By using the above parameters the end user computesDCK′=HDDIi∥Hi∥Di∥Pi∥Rm∥μ1∥μ2∥μ3∥∅1′∥∅2′∥∅3′ and it verifies whether DCK=DCK′. If it holds, the end user accepts the delivery agent message otherwise it will be discarded. Moreover, the end user also checks the dummy identity (incorporated RFID tag) of the delivery agent by calculating Hi and Di.Proof of Correctness(3)Hi=DADIi×Pi=gaj+k+fi×ga−j+fi=gak=K1,Di=Ni×Qi=gak+j+hi×ga−hi+k=gaj=J1,∅1′=μ1θ1+θ2+μ2θ3+θ4=μ1t1−Pm+t2+Pm+μ2t3−Pm+t4+Pm=μ1t1+t2+μ2t3+t4=∅1,∅2′=μ2θ1+θ2−μ3θ3+θ4=μ2t1−Pm+t2+Pm−μ3t3−Pm+t4+Pm=μ2t1+t2−μ3t3+t4=∅2,∅3′=μ1μ3θ1μ2μ3θ4.μ1θ2.μ2θ3=μ1μ3t1−Pmμ2μ3t4+Pm.μ1t2+Pm.μ2t3−Pm=μ1t1+t2μ2t3+t4μ3t1+t4=∅3,Step 3: once the verification of the delivery agent contender key is performed, the end user checks the integrity of the message as follows:(4)esig,Rm.gbHCM=ega,gb,if it holds, then the end user accepts the message otherwise themessage will be rejected.Proof of Correctness(5)esig,Rm.gbHCM=ega1Pm+HCM,gbpm.gbHCM=ega1pm+HCM,gypm+HCM=ega,gbbyusingthebilinearproperty.(iii)
Conditional tracking: if any conflict occurs or any delivery agent is compromised, then the end user can easily detect the real identity of that delivery agent by using the tracking parameterMik. The end user calculates μ2k/μ1j to get Mik with the help of the certj=DADIi∥Rm∥Pi∥Qi∥DCK∥μ1∥μ2∥μ3∥Ni∥θ1∥θ2∥θ3∥θ4.(6)μ2kμ1j=MiJ1t1+t2kK1t1+t2j=Mik.J1t1+t2kK1t1+t2j=Mik.gat1+t2jkgat1+t2jk=Mik.OnceMik is calculated, the end user maps these parameters to the real identity of the delivery agent by using the tracking list. Moreover, the end user revokes the privacy of the delivery agent and removes the compromised DAi from the network to avoid further damage.


## 4.1. System Initialization

The TFH issues system parameters by using the bilinear parametersGa,Gb,p,e as follows: Initially, the TFH selects the random numbers j,k∈Zp∗ as the master secret keys and computes K1=gak and J1=gaj. Then, TFH selects the secure cryptographic hash function H:0,1∗⟶Zp∗. Finally, the TFH issues the FH parameters and broadcasts in the open network platform as FHparam=Ga,Gb,p,ga,gb,K1,J1,H,e.


## 4.2. Delivery AgentDAi Authentication by End Users

In our proposed scheme, the delivery agent authentication process consists ofDAi registration, required keys generation, generation of anonymous certificate and signature, verification of both certificate and signature, and conditional tracking.


### 4.2.1.DAi Registration

Initially,DAi should register in TFH through offline mode. During initial offline registration, the Delivery agent DAi have to submit the necessary information such as user name, address, mail ID, and phone number to the TFH. Once the registration process is successfully completed, the TFH provides credentials to the DAi.


### 4.2.2. Key Generation

AfterDAi registration, the TFH generates the necessary secret keys for the DAi by using a key generation scheme. Initially, the TFH generates the delivery agent’s DAi real identity DRII and also dummy identity DADIi. This DADIi is in-build with an RFID tag. To generate a dummy identity DADIi, the TFH uses two random numbers fi,hi∈Zp∗ and then computes DADIi = gaj+k+fi. Then, the TFH maps the original identity with a dummy identity. Moreover, the TFH creates dummy identities for all delivery agents to check the legitimacy and integrity of the source of information and to track the movement of DAi. Then, the TFH selects random numbers hi and fi such that hi,fi∈Zp∗ and computes Mi = ga1/hi+k+fi and Ni = gak+j+hi for tracking the identity of DAi. Then, TFH places these values DARIi,DADIi,Mik,Nik in the tracking list and issues the delivery agent key Dk to DAi as Dk=DADIi,Mik,Nik,Pi,Qi and this Dk will be kept securely by the delivery agent, where Pi = ga−j+fi and Qi = ga−hi+k. Once the registration and key distribution process is completed, the delivery agent DAi become the authenticated agent for delivering/getting the commodities to/from the end users (farmers/consumers).


### 4.2.3. Anonymous Certificate Generation

The delivery agentDAi perform the following steps to generate the required anonymous certificates.Step 1.
Initially theDAi choose random numbers P1,P2,P3,…,Pr∈Zp∗, where r≤p as short time temporary private keys and computes the short time public keys Rm = gbPm for m=1,2..r.Step 2.
Then, theDAi generate the anonymous one-time certificate certj by using their short-time public keys Rm as follows:
Initially, theDAi randomly selects t1,t2,t3,t4∈Zp∗ and calculates μ1,μ2,μ3,∅1,∅2,∅3, where(1)μ1=K1t1+t2,μ2=MiJ1t1+t2,μ3=NiK1t1+t2,∅1=μ1t1+t2+μ2t3+t4,∅2=μ2t1+t2−μ3t3+t4,∅3=μ1t1+t2.μ2t3+t4μ3t1+t4.
After computingμ1,μ2,μ3,∅1,∅2,∅3, the DAi calculates the delivery agent contender key DCK=HDDIi∥J1∥K1∥Pi∥μ1∥μ2∥μ3∥∅1∥∅2∥∅3∥Rm and then compute the values of θ1,θ2,θ3 and θ4 as below θ1=t1−Pm, θ2=t2+Pm, θ3=t3−Pm, θ4=t4+Pm
Finally, theDAi will generate the anonymous certificate as certj=DADIi∥Rm∥Pi∥Qi∥DCK∥μ1∥μ2∥μ3∥Ni∥θ1∥θ2∥θ3∥θ4.(i)
Signature generation: theDAi generate the short-time signature as sig=ga1/Pm+HCM to maintain the integrity of the message. Then, the DAi broadcasts the message as message=CM∥sig∥certj∥Rm by appending the certificate, signature, and short-time public key. From the received message, the end user extracts the values of DADIi,Pi,Qi,Ni. Moreover, the end-user computes Hi=DADIi×Pi, Di=Ni×Qi, and check whether Hi=K1andDi=J1. If they are equal, then the end user accepts the DAi as an authorised DAi. Initially, the delivery agent sends this message to the end user while communicating with them. The end user authenticates the delivery agent and verifies the integrity of the message. Once the verification is completed, the end user allows the delivery agent to perform their specific function; i.e., the delivery agent (DAi authentication by the end user. Here, the end user (farmer/consumer) will authenticate the delivery agent by using DAi’s certificate Cerj and signature sig by following the verification process.(ii)
Verification process: after receiving theMessage=CM∥sig∥certj∥Rm from the delivery agent, the end user (farmer/consumer) will perform the following steps to authenticate the delivery agent.Step 1: To check the authenticity of the source message, the receiver will calculateHi,Ii,β1′,β2′,β3′ parameters, where(2)Hi=DADIi×Pi,Di=Ni×Qi,∅1′=μ1θ1+θ2+μ2θ3+θ4,∅2′=μ2θ1+θ2−μ3θ3+θ4,∅3′=μ1μ3θ1μ2μ3θ4.μ1θ2.μ2θ3.Step 2: By using the above parameters the end user computesDCK′=HDDIi∥Hi∥Di∥Pi∥Rm∥μ1∥μ2∥μ3∥∅1′∥∅2′∥∅3′ and it verifies whether DCK=DCK′. If it holds, the end user accepts the delivery agent message otherwise it will be discarded. Moreover, the end user also checks the dummy identity (incorporated RFID tag) of the delivery agent by calculating Hi and Di.Proof of Correctness(3)Hi=DADIi×Pi=gaj+k+fi×ga−j+fi=gak=K1,Di=Ni×Qi=gak+j+hi×ga−hi+k=gaj=J1,∅1′=μ1θ1+θ2+μ2θ3+θ4=μ1t1−Pm+t2+Pm+μ2t3−Pm+t4+Pm=μ1t1+t2+μ2t3+t4=∅1,∅2′=μ2θ1+θ2−μ3θ3+θ4=μ2t1−Pm+t2+Pm−μ3t3−Pm+t4+Pm=μ2t1+t2−μ3t3+t4=∅2,∅3′=μ1μ3θ1μ2μ3θ4.μ1θ2.μ2θ3=μ1μ3t1−Pmμ2μ3t4+Pm.μ1t2+Pm.μ2t3−Pm=μ1t1+t2μ2t3+t4μ3t1+t4=∅3,Step 3: once the verification of the delivery agent contender key is performed, the end user checks the integrity of the message as follows:(4)esig,Rm.gbHCM=ega,gb,if it holds, then the end user accepts the message otherwise themessage will be rejected.Proof of Correctness(5)esig,Rm.gbHCM=ega1Pm+HCM,gbpm.gbHCM=ega1pm+HCM,gypm+HCM=ega,gbbyusingthebilinearproperty.(iii)
Conditional tracking: if any conflict occurs or any delivery agent is compromised, then the end user can easily detect the real identity of that delivery agent by using the tracking parameterMik. The end user calculates μ2k/μ1j to get Mik with the help of the certj=DADIi∥Rm∥Pi∥Qi∥DCK∥μ1∥μ2∥μ3∥Ni∥θ1∥θ2∥θ3∥θ4.(6)μ2kμ1j=MiJ1t1+t2kK1t1+t2j=Mik.J1t1+t2kK1t1+t2j=Mik.gat1+t2jkgat1+t2jk=Mik.OnceMik is calculated, the end user maps these parameters to the real identity of the delivery agent by using the tracking list. Moreover, the end user revokes the privacy of the delivery agent and removes the compromised DAi from the network to avoid further damage.


## 4.2.1.DAi Registration

Initially,DAi should register in TFH through offline mode. During initial offline registration, the Delivery agent DAi have to submit the necessary information such as user name, address, mail ID, and phone number to the TFH. Once the registration process is successfully completed, the TFH provides credentials to the DAi.


## 4.2.2. Key Generation

AfterDAi registration, the TFH generates the necessary secret keys for the DAi by using a key generation scheme. Initially, the TFH generates the delivery agent’s DAi real identity DRII and also dummy identity DADIi. This DADIi is in-build with an RFID tag. To generate a dummy identity DADIi, the TFH uses two random numbers fi,hi∈Zp∗ and then computes DADIi = gaj+k+fi. Then, the TFH maps the original identity with a dummy identity. Moreover, the TFH creates dummy identities for all delivery agents to check the legitimacy and integrity of the source of information and to track the movement of DAi. Then, the TFH selects random numbers hi and fi such that hi,fi∈Zp∗ and computes Mi = ga1/hi+k+fi and Ni = gak+j+hi for tracking the identity of DAi. Then, TFH places these values DARIi,DADIi,Mik,Nik in the tracking list and issues the delivery agent key Dk to DAi as Dk=DADIi,Mik,Nik,Pi,Qi and this Dk will be kept securely by the delivery agent, where Pi = ga−j+fi and Qi = ga−hi+k. Once the registration and key distribution process is completed, the delivery agent DAi become the authenticated agent for delivering/getting the commodities to/from the end users (farmers/consumers).


## 4.2.3. Anonymous Certificate Generation

The delivery agentDAi perform the following steps to generate the required anonymous certificates.Step 1.
Initially theDAi choose random numbers P1,P2,P3,…,Pr∈Zp∗, where r≤p as short time temporary private keys and computes the short time public keys Rm = gbPm for m=1,2..r.Step 2.
Then, theDAi generate the anonymous one-time certificate certj by using their short-time public keys Rm as follows:
Initially, theDAi randomly selects t1,t2,t3,t4∈Zp∗ and calculates μ1,μ2,μ3,∅1,∅2,∅3, where(1)μ1=K1t1+t2,μ2=MiJ1t1+t2,μ3=NiK1t1+t2,∅1=μ1t1+t2+μ2t3+t4,∅2=μ2t1+t2−μ3t3+t4,∅3=μ1t1+t2.μ2t3+t4μ3t1+t4.
After computingμ1,μ2,μ3,∅1,∅2,∅3, the DAi calculates the delivery agent contender key DCK=HDDIi∥J1∥K1∥Pi∥μ1∥μ2∥μ3∥∅1∥∅2∥∅3∥Rm and then compute the values of θ1,θ2,θ3 and θ4 as below θ1=t1−Pm, θ2=t2+Pm, θ3=t3−Pm, θ4=t4+Pm
Finally, theDAi will generate the anonymous certificate as certj=DADIi∥Rm∥Pi∥Qi∥DCK∥μ1∥μ2∥μ3∥Ni∥θ1∥θ2∥θ3∥θ4.(i)
Signature generation: theDAi generate the short-time signature as sig=ga1/Pm+HCM to maintain the integrity of the message. Then, the DAi broadcasts the message as message=CM∥sig∥certj∥Rm by appending the certificate, signature, and short-time public key. From the received message, the end user extracts the values of DADIi,Pi,Qi,Ni. Moreover, the end-user computes Hi=DADIi×Pi, Di=Ni×Qi, and check whether Hi=K1andDi=J1. If they are equal, then the end user accepts the DAi as an authorised DAi. Initially, the delivery agent sends this message to the end user while communicating with them. The end user authenticates the delivery agent and verifies the integrity of the message. Once the verification is completed, the end user allows the delivery agent to perform their specific function; i.e., the delivery agent (DAi authentication by the end user. Here, the end user (farmer/consumer) will authenticate the delivery agent by using DAi’s certificate Cerj and signature sig by following the verification process.(ii)
Verification process: after receiving theMessage=CM∥sig∥certj∥Rm from the delivery agent, the end user (farmer/consumer) will perform the following steps to authenticate the delivery agent.Step 1: To check the authenticity of the source message, the receiver will calculateHi,Ii,β1′,β2′,β3′ parameters, where(2)Hi=DADIi×Pi,Di=Ni×Qi,∅1′=μ1θ1+θ2+μ2θ3+θ4,∅2′=μ2θ1+θ2−μ3θ3+θ4,∅3′=μ1μ3θ1μ2μ3θ4.μ1θ2.μ2θ3.Step 2: By using the above parameters the end user computesDCK′=HDDIi∥Hi∥Di∥Pi∥Rm∥μ1∥μ2∥μ3∥∅1′∥∅2′∥∅3′ and it verifies whether DCK=DCK′. If it holds, the end user accepts the delivery agent message otherwise it will be discarded. Moreover, the end user also checks the dummy identity (incorporated RFID tag) of the delivery agent by calculating Hi and Di.Proof of Correctness(3)Hi=DADIi×Pi=gaj+k+fi×ga−j+fi=gak=K1,Di=Ni×Qi=gak+j+hi×ga−hi+k=gaj=J1,∅1′=μ1θ1+θ2+μ2θ3+θ4=μ1t1−Pm+t2+Pm+μ2t3−Pm+t4+Pm=μ1t1+t2+μ2t3+t4=∅1,∅2′=μ2θ1+θ2−μ3θ3+θ4=μ2t1−Pm+t2+Pm−μ3t3−Pm+t4+Pm=μ2t1+t2−μ3t3+t4=∅2,∅3′=μ1μ3θ1μ2μ3θ4.μ1θ2.μ2θ3=μ1μ3t1−Pmμ2μ3t4+Pm.μ1t2+Pm.μ2t3−Pm=μ1t1+t2μ2t3+t4μ3t1+t4=∅3,Step 3: once the verification of the delivery agent contender key is performed, the end user checks the integrity of the message as follows:(4)esig,Rm.gbHCM=ega,gb,if it holds, then the end user accepts the message otherwise themessage will be rejected.Proof of Correctness(5)esig,Rm.gbHCM=ega1Pm+HCM,gbpm.gbHCM=ega1pm+HCM,gypm+HCM=ega,gbbyusingthebilinearproperty.(iii)
Conditional tracking: if any conflict occurs or any delivery agent is compromised, then the end user can easily detect the real identity of that delivery agent by using the tracking parameterMik. The end user calculates μ2k/μ1j to get Mik with the help of the certj=DADIi∥Rm∥Pi∥Qi∥DCK∥μ1∥μ2∥μ3∥Ni∥θ1∥θ2∥θ3∥θ4.(6)μ2kμ1j=MiJ1t1+t2kK1t1+t2j=Mik.J1t1+t2kK1t1+t2j=Mik.gat1+t2jkgat1+t2jk=Mik.OnceMik is calculated, the end user maps these parameters to the real identity of the delivery agent by using the tracking list. Moreover, the end user revokes the privacy of the delivery agent and removes the compromised DAi from the network to avoid further damage.


## 5. Security Analysis

This section discusses the security analysis of our proposed approach. The constraints that are analysed in this section are user privacy, data integrity, and authentication. In this scheme, the signature and certificate generation of the delivery agent are the essential parameters to provide defence against the security attacks such as impersonation, key duplication, and masquerade attacks. In this approach, it is not possible for an outside attacker to generate the valid signatures and certificates of an authorised user. The registration of both the end user entities i.e., registration of both farmer and consumer will be done in the offline mode at the trusted farm-to-home (TFH) platform. The end users will login into the “farm-to-home” application by using the credentials which are given by the TFH at the time of offline registration. So, in our proposed system it is impossible for an attacker to create duplicate keys and inject fake messages into the network. Moreover, in our scheme impersonation attack can’t be performed by the external attacker, because the attacker must acquire the short-term private key of the delivery agent which will be issued by the TFH in the offline mode. In addition, these private keys are only known to the delivery agent. As a result, it is difficult for the attacker to acquire the delivery agent’s information without compromising the offline registration process. The protection against various attacks is described in the following subsection:


### 5.1. Protection against Impersonation Attack

To perform an impersonation attack, an intruder needs to find the confidential parameters of the authenticated user such as,Mi and Ni. For finding the values of Mi and Ni, the attacker has to detect the values of the μ2 and μ3 in the delivery agent’s certificate certj. Moreover, the values of the μ2 and μ3 are calculated as μ2=MiJ1t1+t2 and μ3=NiK1t1+t2. In this μ2 and μ3 equations, t1 and t2 values are the random numbers that are chosen by the users. So, it is difficult for the attacker to find the values of μ2 and μ3 because of Elliptic Curve Discrete Logarithm Problem (ECDLP). It is extremely difficult to find the t1 and t2 in μ2 and μ3 because it involves ECDLP complexity which is represented as p1/2+o1loglog∅ , where the '∅' represents the number of delivery agents. As a result, breaking an anonymous delivery agent certificate and carrying out an impersonation attack is extremely difficult.


### 5.2. Protection against Fake Message Attack

If an attacker wants to send fake messages to the end users, he/she must find the values of the dummy identityDDIi,Pi,Qi, and Ni. Here, Hi=DADIi×Pi=K1 and Di=Ni×Qi = J1. Here, the internal parameters like DADIi,Pi,Qi are generated by the TFH and given to the delivery agent during the offline registration. So, the external attacker is unable to find the values of hi,fi,K1, and J1 that are present in the DADIi,Pi,Qi, and Ni because of the ECDLP. Moreover, the values of hi and fi are selected randomly and the values of the J1 and K1 (master secret keys) are only known to TFH. In addition, the complexity of finding these values based on ECDLP is Op1/2+o1logΘ where 'Θ' represents the number of delivery agents. There is a complexity of O2Θ−1 while finding the hi and fi values. So, it is extremely difficult to find the values of hi,fi,K1, and J1 and to find the values of Hi and Di , as there will be a complexity of Op1/2+o1mlogΘ.2Θ−12 and Op1/2+o1logΘ2.2Θ−1. So, it is hard to carry out a bogus message attack for an attacker. Therefore, our proposed approach can withstand against this attack.


### 5.3. Conditional Privacy Preserving

In our proposed approach, the delivery agent (DAi) generates an anonymous certificate and signature to conceal his true identity. The end user knows only the dummy identity (DADIi) of the DAi. So, the real identity of DAi is hidden. If any miscellaneous activities are observed from the DAi side, then the TFH reveals the real identity of the DAi. Moreover, if the DAi is compromised, then TFH computes the value of μ2k/μ1j to get Mik from the tracking list and revoke the privacy of the particular DAi.


### 5.4. Protection from Nonrepudiation Attack

Our proposed scheme is resistant to nonrepudiation attacks. While receiving the information from theDAi, the authorised end user checks the authenticity of the DAi using an anonymous certificate and signature verification. As a result, the DAi cannot repudiate after getting the information from the end user. End-user repudiation is also not possible, because the end user logs into his account using the valid credentials provided by TFH during initial offline registration. Moreover, login is validated by the OTP sent by TFH at the time of logging in.


### 5.5. Unlinkability

During the information exchange between the delivery agent and end users, our proposed approach provides unlinkability of security parameters such as anonymous certificates and signatures. In our scheme, theDAi uses temporary short time private and public keys to create anonymous certificates and signatures. The lifetime of the keys is noticeably short and is known as short-term keys. The lifetime of these keys will expire after the successful exchange of information by validating the signature and certificate. For further information exchange, new random keys will be generated. Once the generation is completed, these keys get expire and new keys are to be generated for the next information exchange. Thus, short-time keys and unlinkability are interlinked. As a result of this unlinkability, the intruder cannot perform any attacks by detecting DAi′s true identity during the information exchange.


### 5.6. Anonymity and Privacy Preservation

In our proposed scheme, the delivery agents attach a signature and certificate to their confirmation message. So, it is extremely hard to trace the real identity of the delivery agent who signed the message. Moreover, the certificate and signature are generated using short-term private keys that will be changed byDAi after a certain period of time. As a result, attackers will have zero knowledge of the real identity of DAi who signed the messages with their dummy identities. Even if the dummy identities of the DAi are revealed, they are not useful for the external attacker to seek information about the true identity of the particular DAi.


### 5.7. Protecting Against Message Modification Attack

In the message modification attack, an external attacker modifies the message or changes the content of the message before it is received by the end user. In our proposed approach,DAi transfer the message as Message=CM∥sig∥certj∥Rm. Here, a signature is appended to the message. Moreover, a signature is calculated as ga1/Pm+HCM, where Pm is the short-term private key. Its value is only known to DAi, and it is randomly changeable for every exchange of information. So, it is not possible to create duplicate values of the same signature for message modification. Thus, our proposed approach strongly withstands against the message modification attack.


### 5.8. Protecting against the Sybil Attack

This attack is performed by the intruder by sending fake messages to the users. Moreover, the intruder makes the user to believe that the message is from the origin branch. However, in our proposed approach, if an intruder wishes to send a false message, he must know the dummy identity of the delivery agent whereDADIi=gaj+k+fi. Here, j and k are the secret keys that are only known to TFH and fi value is randomly generated for every information transaction. To create multiple identities, the values of these parameters must be known to an external attacker, otherwise, it is impossible for him to create multiple identities for sending fake messages.


## 5.1. Protection against Impersonation Attack

To perform an impersonation attack, an intruder needs to find the confidential parameters of the authenticated user such as,Mi and Ni. For finding the values of Mi and Ni, the attacker has to detect the values of the μ2 and μ3 in the delivery agent’s certificate certj. Moreover, the values of the μ2 and μ3 are calculated as μ2=MiJ1t1+t2 and μ3=NiK1t1+t2. In this μ2 and μ3 equations, t1 and t2 values are the random numbers that are chosen by the users. So, it is difficult for the attacker to find the values of μ2 and μ3 because of Elliptic Curve Discrete Logarithm Problem (ECDLP). It is extremely difficult to find the t1 and t2 in μ2 and μ3 because it involves ECDLP complexity which is represented as p1/2+o1loglog∅ , where the '∅' represents the number of delivery agents. As a result, breaking an anonymous delivery agent certificate and carrying out an impersonation attack is extremely difficult.


## 5.2. Protection against Fake Message Attack

If an attacker wants to send fake messages to the end users, he/she must find the values of the dummy identityDDIi,Pi,Qi, and Ni. Here, Hi=DADIi×Pi=K1 and Di=Ni×Qi = J1. Here, the internal parameters like DADIi,Pi,Qi are generated by the TFH and given to the delivery agent during the offline registration. So, the external attacker is unable to find the values of hi,fi,K1, and J1 that are present in the DADIi,Pi,Qi, and Ni because of the ECDLP. Moreover, the values of hi and fi are selected randomly and the values of the J1 and K1 (master secret keys) are only known to TFH. In addition, the complexity of finding these values based on ECDLP is Op1/2+o1logΘ where 'Θ' represents the number of delivery agents. There is a complexity of O2Θ−1 while finding the hi and fi values. So, it is extremely difficult to find the values of hi,fi,K1, and J1 and to find the values of Hi and Di , as there will be a complexity of Op1/2+o1mlogΘ.2Θ−12 and Op1/2+o1logΘ2.2Θ−1. So, it is hard to carry out a bogus message attack for an attacker. Therefore, our proposed approach can withstand against this attack.


## 5.3. Conditional Privacy Preserving

In our proposed approach, the delivery agent (DAi) generates an anonymous certificate and signature to conceal his true identity. The end user knows only the dummy identity (DADIi) of the DAi. So, the real identity of DAi is hidden. If any miscellaneous activities are observed from the DAi side, then the TFH reveals the real identity of the DAi. Moreover, if the DAi is compromised, then TFH computes the value of μ2k/μ1j to get Mik from the tracking list and revoke the privacy of the particular DAi.


## 5.4. Protection from Nonrepudiation Attack

Our proposed scheme is resistant to nonrepudiation attacks. While receiving the information from theDAi, the authorised end user checks the authenticity of the DAi using an anonymous certificate and signature verification. As a result, the DAi cannot repudiate after getting the information from the end user. End-user repudiation is also not possible, because the end user logs into his account using the valid credentials provided by TFH during initial offline registration. Moreover, login is validated by the OTP sent by TFH at the time of logging in.


## 5.5. Unlinkability

During the information exchange between the delivery agent and end users, our proposed approach provides unlinkability of security parameters such as anonymous certificates and signatures. In our scheme, theDAi uses temporary short time private and public keys to create anonymous certificates and signatures. The lifetime of the keys is noticeably short and is known as short-term keys. The lifetime of these keys will expire after the successful exchange of information by validating the signature and certificate. For further information exchange, new random keys will be generated. Once the generation is completed, these keys get expire and new keys are to be generated for the next information exchange. Thus, short-time keys and unlinkability are interlinked. As a result of this unlinkability, the intruder cannot perform any attacks by detecting DAi′s true identity during the information exchange.


## 5.6. Anonymity and Privacy Preservation

In our proposed scheme, the delivery agents attach a signature and certificate to their confirmation message. So, it is extremely hard to trace the real identity of the delivery agent who signed the message. Moreover, the certificate and signature are generated using short-term private keys that will be changed byDAi after a certain period of time. As a result, attackers will have zero knowledge of the real identity of DAi who signed the messages with their dummy identities. Even if the dummy identities of the DAi are revealed, they are not useful for the external attacker to seek information about the true identity of the particular DAi.


## 5.7. Protecting Against Message Modification Attack

In the message modification attack, an external attacker modifies the message or changes the content of the message before it is received by the end user. In our proposed approach,DAi transfer the message as Message=CM∥sig∥certj∥Rm. Here, a signature is appended to the message. Moreover, a signature is calculated as ga1/Pm+HCM, where Pm is the short-term private key. Its value is only known to DAi, and it is randomly changeable for every exchange of information. So, it is not possible to create duplicate values of the same signature for message modification. Thus, our proposed approach strongly withstands against the message modification attack.


## 5.8. Protecting against the Sybil Attack

This attack is performed by the intruder by sending fake messages to the users. Moreover, the intruder makes the user to believe that the message is from the origin branch. However, in our proposed approach, if an intruder wishes to send a false message, he must know the dummy identity of the delivery agent whereDADIi=gaj+k+fi. Here, j and k are the secret keys that are only known to TFH and fi value is randomly generated for every information transaction. To create multiple identities, the values of these parameters must be known to an external attacker, otherwise, it is impossible for him to create multiple identities for sending fake messages.


## 6. Performance Analysis

In this section, the proposed scheme's performance is evaluated in terms of computation and communication costs. The total cost incurred for the verification of the signature and certificate is known as computational costs. Communication costs are the number of bits needed for information to be communicated.


### 6.1. Computational Complexity

Computational cost refers to the total verification time required for single/n certificates and single/n signatures. This is primarily calculated to verify the authenticity of the delivery agents arriving at the end user and also to check the integrity of the information. The proposed scheme's total verification time is compared to existing works such as Wazid et al. [25], Odelu et al. [26], Kaur et al. [27], and Gong et al. [28]. Let Tp, Th, Tm, and Te represents the time taken to perform the pairing operation, hashing operation, one point multiplication operation and exponential operation, respectively. The Type-Acurve-basedpairing-based cryptography (PBC) library is used to perform all of the above operations. Moreover, for our executions, we used a 2 GHz PC with 8 GB RAM and Cygwin version 1.7.35–15 [29]. Tp, Th, Tm, and Te have time values of 1.6 ms, 2.7 ms, 0.6 ms, and 0.7 ms, respectively. Here, “ms” represents time in milliseconds. The time taken for pairing and hashing operations is more in the calculation of computational cost based on the timing parameters. When compared to the existing schemes, Table 2 clearly shows that our proposed scheme consumes less computational cost. Moreover, in our proposed scheme, there are no single-point multiplicative or additive operations. Further, in our scheme, verifying a single certificate and signature takes only 6.2 ms. Figure 2 clearly shows that our proposed scheme requires less computational time for both signature and certificate verification.Table 2
Computational cost of various schemes.
SchemesFor single signature and certificate verificationFor ‘n’ signature and certificate verificationWazid et al.3Tm+2Tp+Te+5Th3nTm+2nTp+nTe+5nThOdelu et al.3Tm+Te+6Th3nTm+nTe+6nThKaur et al.4Th+2Tm4nTh+2nTmGong et al.5Tp+2nTh1+4nTp+2nThProposed scheme2Tp+5Tex1+nTp+5nTexFigure 2
Signature and verification cost of different schemes.


### 6.2. Communication Cost

The proposed scheme communication overhead is examined and compared to other comparable schemes such as Odelu et al. [26], Wazid et al. [25], Jo et al. [30], and Kaur et al. [27]. The data size of the information exchanged between the delivery agent and the end user is considered to analyse the communication overhead. The proposed scheme considers the size of the confirmation message to be 160 bits, the size of an anonymous signature to be 160 bits, the size of the certificate to be 160 bits, and the length of security parameters such as a public key to be 320 bits. So, the entire message consumes Message=CM∥sig∥certj∥Rm = 800 bits. Table 3 summarises the communication overhead of the proposed scheme and other existing related schemes. The communication cost for different schemes is depicted in Figure 3. As a result, when compared to existing schemes, our proposed scheme evidenced to be notable in terms of communication cost.Table 3
Communication cost of various schemes.
SchemeCommunication cost for a single message (bits)Communication cost forn messages (bits)Odelu et al.29122912nWazid et al.14081408nJo et al.19201920nKaur et al.11201120nProposed scheme800800nFigure 3
Communication cost of different schemes.


## 6.1. Computational Complexity

Computational cost refers to the total verification time required for single/n certificates and single/n signatures. This is primarily calculated to verify the authenticity of the delivery agents arriving at the end user and also to check the integrity of the information. The proposed scheme's total verification time is compared to existing works such as Wazid et al. [25], Odelu et al. [26], Kaur et al. [27], and Gong et al. [28]. Let Tp, Th, Tm, and Te represents the time taken to perform the pairing operation, hashing operation, one point multiplication operation and exponential operation, respectively. The Type-Acurve-basedpairing-based cryptography (PBC) library is used to perform all of the above operations. Moreover, for our executions, we used a 2 GHz PC with 8 GB RAM and Cygwin version 1.7.35–15 [29]. Tp, Th, Tm, and Te have time values of 1.6 ms, 2.7 ms, 0.6 ms, and 0.7 ms, respectively. Here, “ms” represents time in milliseconds. The time taken for pairing and hashing operations is more in the calculation of computational cost based on the timing parameters. When compared to the existing schemes, Table 2 clearly shows that our proposed scheme consumes less computational cost. Moreover, in our proposed scheme, there are no single-point multiplicative or additive operations. Further, in our scheme, verifying a single certificate and signature takes only 6.2 ms. Figure 2 clearly shows that our proposed scheme requires less computational time for both signature and certificate verification.Table 2
Computational cost of various schemes.
SchemesFor single signature and certificate verificationFor ‘n’ signature and certificate verificationWazid et al.3Tm+2Tp+Te+5Th3nTm+2nTp+nTe+5nThOdelu et al.3Tm+Te+6Th3nTm+nTe+6nThKaur et al.4Th+2Tm4nTh+2nTmGong et al.5Tp+2nTh1+4nTp+2nThProposed scheme2Tp+5Tex1+nTp+5nTexFigure 2
Signature and verification cost of different schemes.


## 6.2. Communication Cost

The proposed scheme communication overhead is examined and compared to other comparable schemes such as Odelu et al. [26], Wazid et al. [25], Jo et al. [30], and Kaur et al. [27]. The data size of the information exchanged between the delivery agent and the end user is considered to analyse the communication overhead. The proposed scheme considers the size of the confirmation message to be 160 bits, the size of an anonymous signature to be 160 bits, the size of the certificate to be 160 bits, and the length of security parameters such as a public key to be 320 bits. So, the entire message consumes Message=CM∥sig∥certj∥Rm = 800 bits. Table 3 summarises the communication overhead of the proposed scheme and other existing related schemes. The communication cost for different schemes is depicted in Figure 3. As a result, when compared to existing schemes, our proposed scheme evidenced to be notable in terms of communication cost.Table 3
Communication cost of various schemes.
SchemeCommunication cost for a single message (bits)Communication cost forn messages (bits)Odelu et al.29122912nWazid et al.14081408nJo et al.19201920nKaur et al.11201120nProposed scheme800800nFigure 3
Communication cost of different schemes.


## 7. Conclusion

In this work, a new FHAAPS is proposed to provide secure and efficient anonymous authentication with privacy preservation in the farm-to-home management system. In the FHAAPS, the delivery agent is anonymously authenticated by the end user to check the legitimacy of theDAi. Moreover, this scheme allows the end users to trade with a lot of trusts by providing conditional privacy and security to them. In addition, the privacy of the genuine delivery agent is preserved and the privacy of the compromised delivery agent is revoked from the farm-to-home platform. The security analysis section ensures that the proposed scheme provides the essential security features, and the performance analysis section shows that the proposed scheme performs better than the other existing schemes in terms of computational overhead and communication overhead. Hence, our scheme outperforms the existing scheme and provides an efficient transfer of commodities between the end users and TFH. The future work of this scheme is to create a tracking system for all carrier bags by attaching RFID tags to them, thereby allowing the tracking of goods more efficiently in case of any dispute.



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*Source: 1225675-2023-02-21.xml*