# QuietPlace: An Ultrasound-Based Proof of Location Protocol with Strong Identities
## 7 Security and Privacy Analysis
### Specifications of QuietPlace  
In the two tables below (Tables 3 and 4), we investigate whether QuietPlace covers the above specifications.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Security Specification** & **Covered** & **Description** \\ \hline Data integrity/ & Yes & Sensitive information is protected with hashes, commitments, and encryption. \\  & & It is impossible to modify messages without this being evident. \\ \hline Inability to hide or & Yes & The CA can verify how many witnesses were present during the proof creation \\  & & session and how many sent an LPS to the prover. Thus, if the prover tries to \\  & & add or remove an LPS from his LPA message, CA will detect it. \\ \hline Non-transferability & Yes & The prover always signs his messages. The CA performs checks to verify the \\  & & prover’s identity and signature. The checked information is included in VS, \\  & & which is needed to construct the LP. Thus, no other user will be able to use the \\  & & VS except from the user whose identity is included in it, which is only the \\  & & legitimate prover. \\ \hline Resistance to & & The protocol validates the proximity between prover and witness using \\  & & challenge and response ultrasound messages. Not only do the witnesses count \\  & & the RTT, but also the verifier can check that the RTT reported by each witness \\  & & was correct, by listening to the messages in the video. The usage of ultrasound \\  & & makes resistance to distance fraud stronger, as in order to transmit the \\  & & messages in longer distances, conversion to another type of signal is required \\  & & (i.e., electromagnetic). This increases delay, making the malicious nodes easy to \\  & & be detected. \\ \hline Resistance to mafia & & The usage of random nonces in the witness challenge messages ensures the \\  & & uniqueness of the session. It is impossible for a man in the middle M to replay \\  & & the session between [PERSON] and [PERSON] so that [PERSON] obtains a valid proof, even if he is in the \\  & & possession of [PERSON]’s keys. \\ \hline Resistance to & & The LPSs produced by the witnesses and sent to the prover contain \\  & & session-specific data. Also, messages are signed and the CA performs identity \\  & & and signature checks. Thus, a user cannot use an LPS that belongs to the \\  & & legitimate prover who earned it. \\ \hline Resistance to & & The satisfaction of the above specifications ensures that our protocol prevents a \\  & & prover P’ from cooperating with another prover P, so that [PERSON] obtains a proof for \\  & & P. Even if [PERSON] has shared his keys with [PERSON], the demand for strong identities reveals \\  & & the cooperation. \\ \hline Resistance to & & The prover does not know the identity of the witnesses he communicates with. \\  & & Also, he does not learn their decision, which is sent encrypted. \\  & & The requirement for the witnesses to send a list with other witnesses they \\  & & discover is an additional mechanism for P-W collusion detection. \\ \hline Resistance to & & \\  & & Witnesses do not know each other’s identity or the decision they made. \\  & & The CA checks that the LPA it receives by the prover contains one and only one \\  & & LPS from each witness. \\ \hline No single point & & The CA can become a single point of failure if it malfunctions. However, \\  & & the users can be also registered to other functional CAs. Also, the prover can \\  & & keep the LPA until the CA recovers. \\ \hline \hline \end{tabular}
\end{table}
Table 3: Security specifications of QuietPlace.  
To sum up, QuietPlace covers all the security and privacy specifications.