Information Technology Reference
In-Depth Information
Using IBE supports a flexible access control
mechanism by including the access control in-
formation with the public key itself. In the above
example, Doctor John Smith can only decrypt
data encrypted using the same public string and
which satisfies the access criteria. Moreover, IBE
schemes simplify the key management process
since it does not require the patient or PKG to
keep track of which data is encrypted with what
key. The only obligation here is for the PKG to
authenticate the request and to generate the private
key corresponding to the public string used in the
encryption phase.
The BSN privacy-preserving protocol consists
of 3 main phases:
An initialization phase : during this phase the
patient:
where H if (str) is the if th bit of H(str) and y if is
the if th y public parameter.
3. The signal value is encrypted with the y str
public key using the ECC encryption scheme
determined in the initialization phase.
4. The encrypted signal value is transmitted to
the storage site.
A querying phase : this phase is executed by
the doctor and the PKG. the execution steps are
described as follows:
1. The doctor queries the storage site to retrieve
the encrypted medical data.
2. The doctor requests access to the data by
authenticating with the PKG.
3. The PKG authenticates the request and veri-
fies that all the access control information
in the public key string is satisfied.
4. The PKG generates the private key x str cor-
responding to the public key y str using the
following equation: x
1. Defines an ECC encryption scheme with its
public and private parameters (see the ECC
description in the second section).
2. Specifies a set of n public keys (y 1 ,…,y n ),
n secret keys(x 1 ,…,x n ), and a collision-
resistant hash function H(.) .
3. Loads the public parameters (ECC public
parameters and (y 1 ,…,y n ) together with the
hash function specification H(.) into the BSN
sensor nodes.
4. Securely delivers the n secret keys (x 1 ,…,x n )
to the PKG to support the private key gen-
eration mechanism.
n
1
=
H str
(
)
×
x
,
str
if
if
if
=
where x if is the if th x secret parameter.
5. The PKG securely delivers x str to the doctor
requesting the access.
6. The doctor uses x str to decrypt the medical
data retrieved from the storage site.
By analyzing the security features of the IBE
privacy-preserving scheme, we find that it satis-
fies the privacy requirements presented earlier in
this section. Firstly, the encryption of the medical
data generated by the BSN protects its privacy
and prevents the storage site from revealing its
contents. Secondly, the structure of the public
string used for encryption and the PKG authen-
tication process simplify key management and
support a flexible access control mechanism that
grants the data access permissions as specified
by the patient. Finally, the IBE scheme presented
ensures that no secret keying material is revealed
or medical information is disclosed if a body sen-
A data transfer phase : this phase is executed
by the body sensor nodes to encrypt the sensor
data and send it to the storage site. The steps of
the data transfer phase are presented as follows:
1. The physiological signal value is extracted
from the patient's body.
2. The public key y str is generated from the
agreed upon public string str using the fol-
n
1
lowing equation: y
=
H str
(
)
×
y
,
str
if
if
if
=
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