  Many companies use identity information for different goals. There are a lot
of marketplaces for identity information. These markets have some practical
issues such as privacy, mutual trust and fairing exchange. The management of
identity information is one of the most important applications for blockchain,
for which researchers have proposed a large number of models. In the present
paper, an attempt has been made to solve the problems that mentioned earlier to
exchange identity information on the blockchain. By using the game theory we
propose a fair model of selling authorized identity information in an
environment that include untrusted parties. Moreover, we employ ZK-SNARK to
protect users' privacy. Also, we use proxy re-encryption to record these
informations in IPFS.
