Page 125 - 2023-Vol19-Issue2
P. 125
121 | Rashid et al.
A. Setup and Registration Phases • Upon receiving the sensor’s request, PDi checks the
Symmetric encryption can be represented by the tuple of three
main polynomial–time steps SKE =(Gen, Enc, Dec). Step validity of Si by decrypting function ri = DecShSi (ESi ).
Gen receives a secured factor ? and creates shared key K. Step Then, PDi ri) and com-
Enc depends on K and plaintext m, and produces ciphertext c. computes PW '' = h(PW Si ,
Step Dec depends on K and ciphertext c to produce the real Si
plaintext m. In the proposed scheme, the following steps are '' 'Si .
used: pares PW Si with PW If the results match, the sensor
• Key generation Gen(1? ): The health care center (HCC) is ready to send its signals; otherwise, PDi terminates
runs the key generation step. It uses security factor ?
(where ? represents the length of the secured keys) and this phase.
generates secret key ShSi , ShPDi.
• The above steps are performed once for preserving the
• The HCC is responsible for providing each patient (Pi) energy of the sensor.
the personal device(PDi) and set of sensors based on
his/her case that is diagnosed by doctor (Di). Moreover, PDi needs to login the system via AS for exchang-
HCC provides (Shsi, ShPDi) to Si and PDi, respectively. ing data between. PDi and AS as follows:
PDi may denote the patient’s mobile phone.
• PDi generates an integer random number RA < q; com-
• Pi registers on AS as the following steps:
putes VA = gRA mod q; where q is a prime number, and
– The patient picks his identity (IDPi) and password is g a primitive root modulo q; and computes PW P'i =
(PW Pi ).
h(PW Pi|| ShPDi || RA) and EPDi = E ncShPDi (VA). Then,
– (PDi) computes IDPi = h(IDPi, ShPDi ) and PW Pi = it sends <IDPi, PW Pi' , EPDi > to AS.
h(PW Pi, ShPDi ). Then, it sends IDPi and PW Pi
to AS. • Upon receiving <IDPi, PW P'i, EPDi >, AS ensures
from received information by computing the follow-
ing:
• EPDi is gdeVcA'ryapntdedPWusiPni'g' =VA'h=(PWDePciS||hPSDhi P(EDiP|D| Ri )'.A
R'A =
)
are computed.
– Upon receiving a registration request, AS deter- • PW Pi'' is compared with PW P'i. If the result
mines from its database if Pi is previously recorded. • is a match, AS generates an integer random
If it holds, AS terminates the current phase. Oth- number RB < q; computes VB = gRB mod q,
erwise, it adds the primary parameters computes E'PDi = EncShPDi (VB, Ch); Ch ?
(IDPi, PW Pi, ShPDi, Ph, andRel) of Pi to its database. {1, 0} where AS rebuilds shared secret key
Ph is the phone number of Pi, and Rel represents ShPDi = ShPDi (VA' * RB) for the next go-
the main information of the patient’s relatives ing request session and sends a challenge
(such as brothers, sisters, and friends). (Ch) to tell PDi to compute a new key for a
new login request.
– HCC supports Pi in the set of sensors, and each
one (Si) should be registered in the AS by the HCC Then, it sends <E'PDi > to PDi.
as follows:
* The sensor’s identity is computed based on • Upon receiving <E'PDi >, PDi retrieves VB' , Ch based
its serial number (Senumi ) attached from the DneexctShloPDgii(nEr'ePqDuie)satnSdhPthDei n=gSehnPeDrai tes(aVf'rBe*shRAk)e.yTfhoer
industry company IDSi = h(Senumi ? ShSi ). on
the
* A password (PW Si ) for Si is selected.
main function of Ch provides a pulse to compute a new
* ( IDSi, PW Si ) is sent to PDi.
ShPDi .
B. Login and Authentication Phases Figure 3 explains the organization of the current phases.
The login and authentication processes between Si and PDi C. Healthcare Phase
are executed as below:
• Si selects a random integer value ri ? Z* and calculates In the proposed scheme, three kinds of Si are used: a blood
PW 'Si = h(PW Si , ri) and ESi = EncShSi (ri). pressure sensor, a body temperature sensor, and an oxygen
sensor. The following points explain how sensors work, and
• Si sends < IDSi, PW 'Si , ESi > to PDi. the body temperature sensor is taken as an example:
