  Smart devices have accentuated the importance of geolocation information.
Geolocation identification using smart devices has paved the path for
incentive-based location-based services (LBS). A location proof is a digital
certificate of the geographical location of a user, which can be used to access
various LBS. However, a user full control over a device allows the tampering of
location proof. Initially, to resist false proofs, two-party trusted
centralized location proof systems (LPS) were introduced to aid the users in
generating secure location proofs mutually. However, two-party protocols
suffered from the collusion attacks by the participants of the protocol.
Consequently, many witness-oriented LPS have emerged to mitigate collusion
attacks in two-party protocols. However, witness-oriented LPS presented the
possibility of three-way collusion attacks (involving the user, location
authority, and the witness). The three-way collusion attacks are inevitable in
all existing witness-oriented schemes. To mitigate the inability to resist
three-way collusion of existing schemes, in this paper, we introduce a
decentralized consensus protocol called as MobChain, where the selection of a
witness and location authority is achieved through a distributed consensus of
nodes in an underlying P2P network of a private blockchain. The persistent
provenance data over the blockchain provides strong security guarantees, as a
result, the forging and manipulation become impractical. MobChain provides
secure location provenance architecture, relying on decentralized decision
making for the selection of participants of the protocol to resist three-way
collusion problem. Our prototype implementation and comparison with the
state-of-the-art solutions show that MobChain is computationally efficient,
highly available while improving the security of LPS.
