CAKE: Sharing Slices of Confidential Data on Blockchain

Presented at the CAiSE 2024 Forum, Intelligent Information Systems, June 6th, Limassol, Cyprus.
Synopsis: Cooperative information systems typically involve various entities in a collaborative process within a distributed environment. Blockchain technology offers a mechanism for automating such processes, even when only partial trust exists among participants. The data stored on the blockchain is replicated across all nodes in the network, ensuring accessibility to all participants. While this aspect facilitates traceability, integrity, and persistence, it poses challenges for adopting public blockchains in enterprise settings due to confidentiality issues. In this paper, we present a software tool named Control Access via Key Encryption (CAKE), designed to ensure data confidentiality in scenarios involving public blockchains. After outlining its core components and functionalities, we showcase the application of CAKE in the context of a real-world cyber-security project within the logistics domain.
Paper: https://doi.org/10.1007/978-3-031-61000-4_16

1. CAKE
Sharing Slicesof ConfidentialData on Blockchain
EdoardoMarangone
Michele Spina
Claudio Di Ciccio | https://diciccio.net/| [email protected]
Ingo Weber

2. While collaborators cooperate…
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Signing of the Peace Protocol Between Spain and the United States, August 12, 1898
(source: https://library.whitehousehistory.org/fotoweb/archives/5017-Digital-Library/Main%20Index/Artwork/520.tif.info)
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3. … the whole network observes
06/06/2024Marangone, Spina, Di Ciccio, Weber
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Scene from The Truman Show (1998). Image source: https://redeemingculture.com/film/drama/4106 -the-truman-show-empathy-and-reality

4. Fix this image in your memory
06/06/2024Marangone, Spina, Di Ciccio, Weber
Image source: https://www.makinggameofthrones.com/production -diary/2013/5/29/leeches-dragons-and-a-bear-behind-the-scenes-of-episodes-307.html
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5. Is this the same image?
06/06/2024Marangone, Spina, Di Ciccio, Weber
Image source: https://www.makinggameofthrones.com/production -diary/2013/5/29/leeches-dragons-and-a-bear-behind-the-scenes-of-episodes-307.html
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6. Validation v. understanding
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Image source: https://www.makinggameofthrones.com/production -diary/2013/5/29/leeches-dragons-and-a-bear-behind-the-scenes-of-episodes-307.html

7. Business Process Model and Notation (BPMN)
collaboration diagram
06/06/2024Marangone, Spina, Di Ciccio, Weber
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8. The message, in clear
(as seen by the manufacturer)
06/06/2024Marangone, Spina, Di Ciccio, Weber
80xfd9ffe3578a42d81c4684bd47e6575d9a8f10cc6dab984bd7e19ee0dbacb6287Hash:

9. The message
(as seen by external parties)
06/06/2024Marangone, Spina, Di Ciccio, Weber
90xfd9ffe3578a42d81c4684bd47e6575d9a8f10cc6dab984bd7e19ee0dbacb6287Hash:

10. The message
(as seen by the electronic parts supplier)
06/06/2024Marangone, Spina, Di Ciccio, Weber
100xfd9ffe3578a42d81c4684bd47e6575d9a8f10cc6dab984bd7e19ee0dbacb6287Hash:

11. The message
(as seen by the mechanical parts supplier)
06/06/2024Marangone, Spina, Di Ciccio, Weber
110xfd9ffe3578a42d81c4684bd47e6575d9a8f10cc6dab984bd7e19ee0dbacb6287Hash:

12. Hence the name: CAKE
06/06/2024Marangone, Spina, Di Ciccio, Weber
Image source: https://heriots.co.uk/products/pistachio
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13. Ingredients
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•A cup of IPFS
(distributedhash-table-based file syst.)
To store encrypted files
•A slather of CP-ABE
(cryptography)
To selectively encrypt documents
•A tad of Ethereum
(blockchain)
To keep track of the exchanges
•A scoop of Solidity
(smart contract)
To mediate the data exchange
Image source: https://heriots.co.uk/products/pistachio

14. Your kitchen
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15. CP-ABE
•Attribute-Based Encryption (ABE): type of public-key encryption
•Ciphertext-PolicyABE (CP):
We associate rolesand process instancewith attributes
(propositionalliterals)
Messagesare associated withpolicies
(propositional formulae on attributes)
•Attributes:
14548487, Supplier, Electronics, Mechanics, Manufacturer
•Policy:
14548487 AND (Manufacturer OR (Supplier AND
Electronics))
06/06/2024Marangone, Spina, Di Ciccio, Weber
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Process
instance ID
Roles

16. Example
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14548487, Supplier, Mechanics
Why?

17. CAKE
Sharing Slicesof ConfidentialData on Blockchain
EdoardoMarangone
Michele Spina
Claudio Di Ciccio | https://diciccio.net/| [email protected]
Ingo Weber
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