=Paper=
{{Paper
|id=Vol-2980/paper329
|storemode=property
|title=A
WebProtégé Plugin for Attesting to the Provenance of Ontologies on the Ethereum
Blockchain
|pdfUrl=https://ceur-ws.org/Vol-2980/paper329.pdf
|volume=Vol-2980
|authors=Simon Curty, Hans-Georg Fill, Rafael Gonçalves, Mark Musen
|dblpUrl=https://dblp.org/rec/conf/semweb/CurtyFGM21
}}
==A
WebProtégé Plugin for Attesting to the Provenance of Ontologies on the Ethereum
Blockchain==
https://ceur-ws.org/Vol-2980/paper329.pdf
A WebProtégé Plugin for Attesting to the
Provenance of Ontologies on the Ethereum
Blockchain
Simon Curty1[0000−0002−2868−9001] , Hans-Georg Fill1[0000−0001−5076−5341] ,
Rafael S. Gonçalves2[0000−0003−1255−0125] , Mark A. Musen3[0000−0003−3325−793X]
1
University of Fribourg, Digitalization and Information Systems Research Group
{simon.curty,hans-georg.fill}@unifr.ch
2
Harvard Medical School, Center for Computational Biomedicine
rafael goncalves@hms.harvard.edu
3
Stanford University, Stanford Center for Biomedical Informatics
musen@stanford.edu
Abstract. Ontologies are shared, formal conceptualizations of a domain
that are consumed by human and machine agents alike. Trust in ontolo-
gies is a central issue for their application. For example, machine learning
algorithms for medical diagnosis may rely on the correctness of ontolo-
gies and could potentially deliver false results. For enhancing trust, we
developed a WebProtégé plugin for the decentralized attestation and ver-
ification to the integrity and validity of ontologies using the Ethereum
blockchain. Blockchains are an immutable, tamper-resistant and decen-
tralized storage where all transactions are digitally signed. Thus, they
permit tracing the provenance of concepts and identify responsible ac-
tors. For a first experimental evaluation, we evaluated the transaction
costs for attesting to the provenance of ontologies.
Keywords: Ontology · Attestation · Blockchain · Ethereum · WebProtégé
1 Introduction
With the recent integration of linked data, knowledge representations and ma-
chine learning in the semantic web, it has become essential both for human
and machine agents to know about the provenance of data and derived informa-
tion [7,5]. Thereby, ontologies play a central role as a formal knowledge resource.
Through blockchains as append-only, immutable, decentralized and distributed
data stores, trust is achieved through full transparency of the recorded, digitally-
signed transactions that are verified through peer-to-peer consensus protocols.
In this work we therefore present a plugin for the WebProtégé collaborative
ontology editor which enables the attestation to the provenance of ontologies
using the Ethereum blockchain. In contrast to the full storage of ontologies on
blockchains, which is infeasible due to the limited storage space and compar-
atively high transaction costs, attestations permit decentralized, verifiable, and
Copyright © 2021 for this paper by its authors. Use permitted under Creative
Commons License Attribution 4.0 International (CC BY 4.0).
Curty, S. et al.
transparent proofs of the existence and integrity of information without stor-
ing the information itself [6]. In addition to its adequacy for blockchain-based
applications, attestation further prevents the disclosure of the underlying in-
formation, while still allowing for conducting proofs of existence via so-called
zero-knowledge-proofs if required [4].
2 Related Work
Traditionally, digital signatures of ontologies have been used for so-called policy-
based trust. As a foundation for deriving signatures for RDF graphs, Carroll pro-
posed a canonicalization of RDF graphs without changing their semantics [3].
An approach for computing a digest of RDF graphs for content identifiers with-
out the need for canonicalization was discussed by Sayers and Karp [11]. Based
on this, Kasten et al. described the signing of individual sub-graphs [10]. How-
ever, digital signatures typically rely on a centralized public-key infrastructure
whereas blockchains offer a decentralized, distributed, peer-to-peer architec-
ture [14]. Multiple benefits have been previously identified for applying block-
chains in the semantic web [2], e.g., for using RDF as the data storage format on
blockchains and thus providing a decentralized, immutable, tamper-proof data
storage for RDF graphs [12]. Another approach has been proposed in the form
of knowledge blockchains for the transparent monitoring of ontology evolution
and proving the existence of concepts without disclosing them using so-called
zero-knowledge proofs [4]. Tuán et al. presented a hybrid approach for storing
RDF triplets for use in edge networks, where triplets are stored in a distributed
off-chain RDF store but access is controlled by smart contracts [13].
3 Extension of WebProtégé for Enabling Ontology
Attestations
The cloud-based, collaborative WebProtégé editor is a well-established platform
for ontology authoring, which can be extended through a plugin system in the
form of portlets [9]. Therefore we chose it as foundation for realizing our im-
plementation for attesting to the provenance of ontologies. The implementation
is composed of three major components. A plugin (i) for WebProtégé offers the
UI for attesting to or verifying a loaded ontology. For that purpose, a digest of
the ontology is calculated by reverting to the OWL API [8]. Further, a transac-
tion containing the attestation information (IRI, version IRI, digest, name of the
signer) to the Ethereum blockchain is initiated. The connection and interaction
with the chain network is provided by Metamask4 (ii), a browser wallet exten-
sion. Transactions are submitted to the network from a user account, i.e. users
are prompted to login with their Ethereum account and authorize the transac-
tion. Thereby, the transaction is digitally signed and sent to a smart contract
4
Metamask - https://metamask.io/
A WebProtégé Plugin for Attesting to the Provenance of Ontologies
(iii) on the chain. The contract stores the received data, thus irrevocably per-
sisting the attestation information. Finally, a user may query the smart contract
to verify if an ontology has been attested to or was changed. The result of the
verification presents the user with information on the time and date of the at-
testation as well as on who attested to the origin of the ontology. In this way
it can for example be inferred in a decentralized fashion and without someone
having to host the ontology centrally that an expert has validated and attested
to the provenance of an ontology, thus increasing the trust that can be placed
in that ontology.
Fig. 1. The attestation portlet integrated into WebProtégé (on the right). A demon-
stration can be found at https://www.youtube.com/watch?v=1iuoYz_WTeo
4 Experimental Evaluation
In Ethereum, size and computational complexity of transactions are measured in
an energy unit, called Gas. This is a fee payed by the originator in the cryptocur-
rency Ether and depends on the complexity of commands to be executed [1]. The
Ether price of a unit of gas is influenced by the transaction volume. Figure 2
shows historical transaction fees in USD for an attestation in comparison to a
baseline, a contract storing a 256bit integer value. E.g., on 1. June 2021, an
ontology attestation would have cost USD 8.62 (vs. baseline of USD 3.25). Both
gas and ether price are highly volatile. As such, the transaction cost may change
significantly in a short period of time.
However, Ethereum is in the process of adopting the proof-of-stake consen-
sus mechanism5 , enabling higher transaction throughput and better energy ef-
ficiency. Alternatively, our approach may be adapted to other blockchain-based
systems, e.g., Avalanche6 , an Ethereum compatible proof-of-stake blockchain,
5
See https://ethereum.org/en/developers/docs/consensus-mechanisms/pos/
6
Avalanche - https://www.avax.network/
Curty, S. et al.
or the Bloxberg infrastructure7 for decentralized services for the scientific com-
munity. We provide the experimental dataset and prototype implementation as
open source8 . The attestation approach, in form of a portlet plugin, has been
integrated in a fork of the original WebProtégé distribution. Submitting autho-
rized transactions to the chain network is not handled by the plugin itself, but
instead delegated to the required browser wallet extension (Metamask). Thus,
users are required to install this extension prior to using the plugin. In return,
users retain full control of chain interactions.
Cost of ontology attestation in USD since Jan. 2020
1000
Mean cost for attestation
Baseline transaction cost
100
Transaction Cost [USD] (log10)
10
1
0.1
0.01
01/20 03/20 05/20 07/20 09/20 11/20 01/21 03/21 05/21
Date [month/year]
Fig. 2. Transaction costs for attestations based on the price for ETH. The attested
ontology only has a minor influence on the incurred costs as the digest length is fixed
but the IRI and the signer’s name are not.
5 Conclusion
In this paper we described a WebProtégé plugin for attesting to the provenance
of ontologies using the Ethereum blockchain. The feasibility of the approach has
been evaluated through a prototypical implementation and a cost evaluation.
7
Bloxberg infrastructure - https://bloxberg.org/
8
Repository - https://github.com/curtys/webprotege-attestation-base
A WebProtégé Plugin for Attesting to the Provenance of Ontologies
Future work will include the investigation of alternative hashing procedures for
ontologies for enabling zero-knowledge proofs on a more fine granular level and
the extension of the smart contract implementation towards supporting attesta-
tions by multiple users.
Acknowledgments
The research on this paper has been partially financed by the Swiss National
Science Fund grant number 196889.
References
1. Antonopoulos, A.M., Wood, G.: Mastering ethereum: building smart contracts and
dapps. O’reilly Media (2018)
2. Cano-Benito, J., Cimmino, A., Garcı́a-Castro, R.: Towards blockchain and seman-
tic web. In: Business Information Systems Workshops. pp. 220–231. Springer (2019)
3. Carroll, J.J.: Signing RDF Graphs. In: ISWC. pp. 369–384. Springer (2003)
4. Fill, H.G.: Applying the Concept of Knowledge Blockchains to Ontologies. In:
AAAI 2019 Spring Symposium. CEUR-WS.org (2019)
5. Fill, H., Härer, F.: Supporting trust in hybrid intelligence systems using
blockchains. In: AAAI 2020 Spring Symposium. CEUR-WS.org (2020)
6. Härer, F., Fill, H.: Decentralized Attestation of Conceptual Models Using the
Ethereum Blockchain. IEEE CBI Conference 01, 104–113 (2019)
7. van Harmelen, F., ten Teije, A.: A boxology of design patterns for hybrid learning
and reasoning systems. J. Web Eng. 18(1-3), 97–124 (2019)
8. Horridge, M.: OWL API main repository. https://github.com/owlcs/owlapi (2020)
9. Horridge, M., Gonçalves, R.S., Nyulas, C.I., Tudorache, T., Musen, M.A.:
WebProtégé: A Cloud-Based Ontology Editor. In: World Wide Web Conference.
pp. 686–689. ACM (2019)
10. Kasten, A., Scherp, A., Schauß, P.: A Framework for Iterative Signing of Graph
Data on the Web. In: ESCW Conference. pp. 146–160. Springer (2014)
11. Sayers, C., Karp, A.: Computing the digest of an RDF graph. Tech. rep.,
HP Laboratories Palo Alto (2004), https://www.hpl.hp.com/techreports/2003/
HPL-2003-235R1.pdf (last access 2021-04-09)
12. Sopek, M., et al.: GraphChain: A Distributed Database with Explicit Semantics
and Chained RDF Graphs. In: The Web Conference 2018. pp. 1171–1178. ACM
(2018)
13. Tuán, A., Hingu, D., Hauswirth, M., Le-Phuoc, D.: Incorporating Blockchain into
RDF Store at the Lightweight Edge Devices. In: Int. Conf. on Semantic Systems.
pp. 369–375. Springer (2019)
14. Yakubov, A., Shbair, W.M., Wallbom, A., Sanda, D., State, R.: A blockchain-based
PKI management framework. In: IEEE/IFIP Network Operations and Manage-
ment. pp. 1–6. IEEE (2018)