A Privacy-Preservation Scheme based on Mobile Terminals in Internet Medical

Since the 21st century, Internet technologies have entered a stage of rapid developments, and gradually been widely used in various industries. Internet Medical is gradually matured and used widely. Aiming at the problems such as the easy leakage of privacy in mobile medical equipment and untrustworthy data, we make use of a role-separated mechanism to generate trusted anonymous certificates and propose a lightweight identity authentication scheme to protect the medical data security. It reduces the calculation cost. Meanwhile, in view of problems of transparency and visibility of blockchain information, we adapt searchable encryption algorithm to realize ciphertext processing in the whole life cycle. Experiments show that our scheme can reduce the cost of computation on basis of ensuring traffic. In process of dynamic updating of ciphertext keywords, except the keyword identifier, less information is leaked to the server, which protect users’ privacy.


Introduction
Medical problems including medical care access and quality are common around the world. Medical resources are in short supply and it is difficult to distribute them evenly. Large numbers of individuals do not receive the quality care that they need [1]. Even geographical problems such as economic differences between different regions, topography and topography bring various difficulties to medical health. These In this paper we mainly discuss privacy-preservation solutions of mobile terminals in Internet Medical, which integrates the application of lightweight authentication, blockchain technology, anonymous certificates and searchable encryption technology to realize the encrypted calculation and ciphertext of mobile medical device data. Data sharing has been implemented, and privacy-preservation of medical data has been implemented. In 2017, Al Omar et al. [5] proposed a data management system for patient health care. By adopting blockchain to protect privacy storage, it solved the problem of losing control when storing encrypted data in the system. In addition, by using encryption on the blockchain, the framework will not be affected by data preservation vulnerabilities.

Related Works
In 2018, Gabor Magyar [6] designed an integrated health information model that builds a decentralized and openly scalable network based on the blockchain operating environment, making access to data more secure. In order to handle the protected health information (PHI) generated by these devices, Kristen N. Griggs [7]  can provide services to patients and regularly analyse data to provide better services. The HGD architecture based on blockchain proposed by Yue [14] et al.
enables patients to safely control and share medical data. Aiming at the privacy of medical data, Tian [15] et al. proposed to establish a shared key that can be reconstructed by legitimate parties before the diagnosis and treatment process begins.   Fig.1 The System Structure

Module Anonymous Certificate Generation
The steps to generate an anonymous certificate are as follows.
Step 1: A user submits the real-name certificate application and his real identity information to the CA.
After the CA verifies, the real-name certificate Ecert will be issued for the user and saved in the CA database.
Step 2: User U generates his own anonymous identity AID , public and private key pair Step 4: After the user accepts w , he uses ASK to perform signature calculation on M which is ig (M) ASK S , and send random numbers 1 r and w to TCA .
Step  g (13) and send it to the user, User U gets the anonymous in the end. The time when the smart wearable device first received a local computer message.

Lightweight Authentication
The time when the local computer first received the smart wearable device.
The time when the local computer first received the blockchain node message.
The time when the blockchain node first received a local computer message.

TY 
Maximum transmission delay allowed in the system.

EPD
Pseudonyms for smart wearable devices.

next EPD
Next-round communication pseudonyms for smart wearable devices.

ID
Identifier of smart wearable device.

K
Shared key value between smart wearable device and blockchain node. The steps required for lightweight authentication are as follows. Step Step 2: The smart wearable device feeds Step  Steps of the searchable encryption scheme are as follows.
Step 1: ( , and we get the key 12 ( , ) K k k  . Step We get ( , , ) c  and  are empty sets at this time.
Step 3: , for the keyword w to be searched, calculate the search label: and the formula can be expressed as follows: , and its formula can be expressed as follows:

Analysis of Searchable Encryption
Description of relevant symbols are as shown in Table 5. The performances of our scheme are compared with other references, and the results are shown in Table 6.  The random number is randomly generated by the system, and it is unpredictable and inconsistent.
Therefore In our scheme, we disclose specific information to the server during the operations of query and update.
Next, we use the following leak functions Lsearch, Ladd, Ldelete, Lencrypt to give the leaked information.
Relevant parameters are shown in Table 5. According to the above leak functions, except access models, our scheme doesn't disclose more information to the server.

Conclusions
As an intelligent product at this stage, mobile intelligent terminal integrates the existing information system of the hospital through mobile Further works are as follows: (1) To improve the efficiency of searchable encryption.
(2) To expand diversified search functions. Except the basic search function, we also need to support some special functions, such as approximate search, wildcard search, fuzzy search, multi-keyword search and so on.

Acknowledgments
We sincerely thank the Reviewers and the Editor for their valuable suggestions.

Authors' contributions
Shuo Gao and Zekai Liu designed the framework of this scheme.
Yihan Liu and Qichao Wang designed the core algorithm and performed the experiments. Wei Ou provided technical supports. All authors reviewed and approved final manuscript.

Authors' information
Shuo Gao is a student of Hainan University. His research interests include information security and cyber security.

Funding
Not applicable.

Availability of data and materials
There is no supporting data available.