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Jiang et al. J Surveill Secur Saf 2020;1:61-78 I http://dx.doi.org/10.20517/jsss.2020.09 Page 67

Figure 2. The presented data structure model

,
KeyGen (PP , msk , ID A , ID B ) → (d A ,d K AB , KAB ) : This algorithm is a probabilistic algorithm implemented
B
by KGC. The public parameter PP, the master key msk, and patient’s identity ID along with physician’s

A
identity ID are the inputs, and KeyGen generates a private key d for patient A and a private key d for
A
B
B
physician B. This algorithm outputs a session key K and secret key KAB for auditing.
AB
Extract (PP , ,F KAB ) → (F * , ,{ }τσ ii ∈ [1, ] n ) : This algorithm is a probabilistic algorithm run by a user. The user is
given system parameters PP, key KAB , file F and its file name. It outputs a verifiable file tag t, a set of block
authenticators{}σ ii ∈ [1, ]n of the processed file blocks {}χ ii ∈ [1, ]n .
Audit (PP , )τ → {0,1}: This algorithm is a probabilistic algorithm jointly run by the auditor and cloud server.
It outputs 1 to indicate all of the data block can be verified to be original and integrated by t.

3.3 Stereo storage structure
The novel stereo storage structure proposed in this paper is aimed to realize fast retrieval and query of data
and assist the auditing protocol in the e-health system. As is shown in Figure 2, a three-dimensional storage
structure is designed to store mass amounts of medical data from the users. Specifically, each plane of the
three-dimensional structure on the left part of the figure contains a header file and a series of f diagnosis
and treatment files of a certain physician corresponding to a certain patient. The header file contains the
identity information of the physician and the patient, which is convenient for quick search of the file. Here,
1 ≤ f ≤ , and is the upper limit of file number of each plane in the stereo storage structure. And those
medical files contained in one plane can be generated, shared with, and verified for integrity by both of the
specific physician and the patient. In other words, all diagnosis and treatment files of a physician D for one
d
of his/her patients P are stored in the same plane. For example, F represents the f-th files of the physician
P
1,1,f
D and the patient P , and F represents the f-th files of the physician D and the patient P . In the same
1
2
1,2,f
1
1
way, the patient P can also consult with the physician D , during which a series of files will be generated.
2
2
In this e-health system, we suppose the user set contains a set of physician D and a set of patient P, and
the index of the physician and patient is d and p, respectively. Here, the f-th files of the physician D and
d
the patient P is denoted as F , and the header file of this series of files in the same plane is represented as
P
d,p,f
F . In addition, the f files corresponding to one of the planes are shown on the right in the figure, which
d,p
together form a smaller three-dimensional storage structure. Each plane in the right picture represents
a file. In order to better process the file data, we uniformly divide each file into n blocks and each block