4 - The TEE receives the smart contract, after it verifies the state of the doctor.
Then, it extracts the public key of the doctor and calculates its hash and compares it
with the hashes in T ht
5 - The patient signs smart contract acceptation with his\her private key and sends it
to the TEE using Blockchain.
6 - The Blockchain sends the signed SC patient with K priv to the TEE.
7 - TEE creates a file that contains a list of demanded data with IPFS hashes, @IPFS
and the time stamp and send it to the IPFS.
8 - IPFS verifies the validity of (@ IPFS + H IPFS , time stamp).
9 and 10 - TEE executes the SC and returns the execution result to the Blockchain.
4 Security Analysis
Table 2 presents a comparison between three previous solutions and our proposed
solution. We observe that the others solution does not respect all the criteria of security.
When using this approach, the 5 key criteria of security are guaranteed or maintained. in short, user data can only be modified, accessed or deleted by authorized
persons (integrity; privacy and integrity).
The IPFS contains the data in a homomorphic way (decentralization) and the
execution in TEE will be based on the encrypted data, without forgetting that the TEE
and IPFS platforms only allow access to authorized persons.
5 Conclusion
The Blockchain technology has reached a great boom in many sectors such as e-health,
e-commerce; e-vote… The main important Blockchain [11] characteristics are:
Transparency, no need for third parties and instant access to data since it is replicated
on all nodes. To create a secure smart contract based on Blockchain, a new solution is
presented which combines three technologies: Blockchain, TEE, and IPFS in order to
take advantage of their benefits. This approach is based on collecting the necessary data
from distributed database while protecting the user’s privacy and executing it in TEE.
Table 2. Comparison approaches
Articles
Confidentiality Privacy Authenticity Integrity Decentralization
Hawk [10]
+
+
+
+
−
BC and SC for digital
certificate [8]
+
−
+
+
+
Towards using
BC technology for
e-Health data access
management [11]
+
−
+
+
+
Our solution
+
+
+
+
+
284
F. Yahmed and M. Abid
Then, it extracts the public key of the doctor and calculates its hash and compares it
with the hashes in T ht
5 - The patient signs smart contract acceptation with his\her private key and sends it
to the TEE using Blockchain.
6 - The Blockchain sends the signed SC patient with K priv to the TEE.
7 - TEE creates a file that contains a list of demanded data with IPFS hashes, @IPFS
and the time stamp and send it to the IPFS.
8 - IPFS verifies the validity of (@ IPFS + H IPFS , time stamp).
9 and 10 - TEE executes the SC and returns the execution result to the Blockchain.
4 Security Analysis
Table 2 presents a comparison between three previous solutions and our proposed
solution. We observe that the others solution does not respect all the criteria of security.
When using this approach, the 5 key criteria of security are guaranteed or maintained. in short, user data can only be modified, accessed or deleted by authorized
persons (integrity; privacy and integrity).
The IPFS contains the data in a homomorphic way (decentralization) and the
execution in TEE will be based on the encrypted data, without forgetting that the TEE
and IPFS platforms only allow access to authorized persons.
5 Conclusion
The Blockchain technology has reached a great boom in many sectors such as e-health,
e-commerce; e-vote… The main important Blockchain [11] characteristics are:
Transparency, no need for third parties and instant access to data since it is replicated
on all nodes. To create a secure smart contract based on Blockchain, a new solution is
presented which combines three technologies: Blockchain, TEE, and IPFS in order to
take advantage of their benefits. This approach is based on collecting the necessary data
from distributed database while protecting the user’s privacy and executing it in TEE.
Table 2. Comparison approaches
Articles
Confidentiality Privacy Authenticity Integrity Decentralization
Hawk [10]
+
+
+
+
−
BC and SC for digital
certificate [8]
+
−
+
+
+
Towards using
BC technology for
e-Health data access
management [11]
+
−
+
+
+
Our solution
+
+
+
+
+
284
F. Yahmed and M. Abid