## 4 Proposed Scheme
### Identity, Route, and Location Privacy (IRL)
Rather, it provides positive effects in terms of strengthening the route and source location privacy, because these effects will helps to increase the safety period [3], which is the time for an adversary to reach at the source node. _Identity Privacy_: Whenever a node receives the packet \(p\) from the source node or en-route node then the receiving node will replace the previous hop's identity \(prev_{hop}\) contained in the packet with its own (Algorithm 1, Line 13). After that, the node will get the next forwarding node \(next_{hop}\) (as described earlier) and update the header of the packet \(p=\{prev_{hop},next_{hop},payload\}\) (Line 14). After modification of the two header fields, the node will forward the packet (Line 16). In this way, all the intermediate forwarding nodes replace the source and next hop's identity contained in the packet \(p\). This process will go on until the packet reaches the base station. _Location Privacy_: The neighboring nodes which are in each other's radio range can easily approximate the location of each other by measuring the received signal strength and the angle of arrival [28]. If the adversary is within the range of the source node, then adversary can easily estimate the location of the source. Once the packet has crossed the radio range of the original source node, then becomes very difficult for an attacker to estimate the location of the node either in terms of the physical distance or in terms of the number of hops of an original source node. The main reason for this is that the path selection is random and packets are forwarded by only trusted nodes which only contain the information of the last and the next hop. ### Reliable Identity, Route, and Location Privacy (r-IRL)

It is also possible that some applications require more reliability in terms of packet reach-ability; and the packet could be dropped due to either network congestion or malicious behavior of an en-route node. Thus, in order to achieve more reliability, the packet should be forwarded from multiple paths simultaneously, which will give trustworthiness in the sense that at least the packet should reach the base station by any one of the paths, although, this may increase some communication overhead. Our reliable IRL (r-IRL) algorithm is the extended version of our proposed IRL algorithm, in which we introduce one more parameter, reliability \(r\). The source node \(i\) will multi-cast a packet to all \(r\) randomly selected neighboring trusted nodes that are in the forward direction. If there are no adequate trusted nodes present in the forward direction, then it will select the remaining trusted nodes from the backward direction. The rest of the mechanism of the r-IRL algorithm is the same as the IRL algorithm. ### Data Privacy

The payload contains the identity of the source node (\(ID_{x}\)) and the actual data (\(d\)). Identity is encrypted with the public key (\(k_{bs}^{+}\)) of the base station and data is encrypted with the secret key (\(k_{x,bs}\)) shared between the sender node and the BS. Both are appended with the payload as shown below:

\[payload=[E(ID_{x},k_{bs}^{+}),E(d,k_{x,bs})]\]If we assume that the adversary knows the range of identities assigned to the sensor nodes, public key of the base station and information about cipher algorithm used in the network, an adversary can then successfully obtain the identity of the source by performing simple brute-force search attack [29] by comparing the pattern of encrypted identity with a known range of identities. Therefore in order to provide protection against brute-force search attack, we append a random number \((R_{n})\) (equivalent to the size of identity) with the identity of a node and then perform encryption. Now the payload is:

\[payload=[E(ID_{x}||R_{n},k^{+}_{bs}),E(d,k_{x,bs})]\]

where \(||\) is the append operation. Inclusion of random number may introduce additional computational overhead. However, the amount of overhead is mainly dependent on random number generation technique.