“I’m still / I’m still / Chaining from the Block”

“An Outlook of the Ongoing and Future Relationship between Blockchain Technologies and Process-aware Information Systems.” Invited talk at the joint workshop on Blockchain for Information Systems (BC4IS) and Blockchain for Trusted Data Sharing (B4TDS), co-located with with the 36th International Conference on Advanced Information Systems Engineering (CAiSE), 3 June 2024, Limassol, Cyprus.

1. “I’m still / I’m still /
Chaining from the
Block”
An Outlook of the Ongoing and Future Relationship
between Blockchain Technologies and Process-aware
Information Systems
Claudio Di Ciccio | https://diciccio.net/| [email protected]
Utrecht University, Netherlands

2. Claudio Di Ciccio
Associate professor
Ph.D. in Computer Science and Engineering
Faculty of Science /
Software Division /
Process Science Group
Main research interests:
formal methods &
logic and computation,
applied in
process analytics &
blockchain architectures
Claudio Di Ciccio 03/06/2024
2

3. My experience so far
03/06/2024Claudio Di Ciccio
Latina, Italy
(B.Sc)
Rome, Italy
(M.Sc, Ph.D)
Vienna, Austria
(Post-doc,
Assistant Prof.)
Rome, Italy
(Assistant Prof.,
Associate Prof.)
Utrecht, Netherlands
(Associate Prof.)
3

4. Transaction
•Transfer of (crypto)assets(Ether, Bitcoin, Algo, …)
from accountA to accountB
Externally Owned
Account (EOA)
Externally Owned
Account (EOA)
Digital signature
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Transaction ID: 0xfa12…40c6da

5. Ledger
•Ordered collection of transactions
•The ordermatters!
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6. Amsterdam, 1856
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•About 2000 shipsdeparted on an annual
basis
•Seafarers
numerous
a vital contribution to trade
wages paid after a journey
(always in need of credit)
•Non-bank credit markets
Shopkeepers and boarding-house keepers
as lenders
•The Discipline Act (1856)
Forbids the use of seafarers’ wages as
redemption payments
Image source: https://www.istockphoto.com/nl/vector/amsterdam -in-the-19th-century-gm538063610-95625387

7. The ledger of the
water bailiff’s
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•The Discipline Act prescribed that
lenders had to present their unredeemed
IOUs to the water bailiff’s during the
month of July 1856
•Every IOU recorded basic information,
including:
the dateon which it was entered
the names of lenderand borrower
the unredeemed amount
•13,708 loans were registered in a
443-page ledger
A hand-drawn ink lithography of men writing a ledger in the water bailiff's office in 1856 (DALL-E, https://openai.com/dall-e-2/)

8. Block
•Blocks group and collate transactions
•The order matters!
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9. Hashing the previous block for immutability
•Blocks refer back to direct predecessors via hashing
•The order matters!
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10. The blockchain remembers
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11. Centralised ledger
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“In Amsterdam, the water bailiff’s office was
located in the […] middle of one of the
seafarers’ quarters […] open for registering
IOUs six days per week.
On one occasion, clerks […] worked
overtime on a Sunday: presumably
because the company of H. Lond, one of
the largest lenders in town, had delivered its
1314 unredeemed IOUs the day before and
they did not want to start the new week with
such a backlog”

12. Decentralisation for persistence
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Centralisation Decentralisation
Warning: possible information inconsistency→ proof-of-* and consensus

13. Private|public/ Permissioned|permissionless
Transactability / visibility
Private Public
Consensus
Permissionless
Selectednodes can
transact and view,
everynode can
participate in consensus
Everynode can
transact and view and
participate in consensus
Permissioned
Selectednodes can
transact and view, a
subset of which can
participate in consensus
Everynode can
transact and view,
selectednodes
participate in consensus
03/06/2024Claudio Di Ciccio
Anderberget al. “Blockchain Now And Tomorrow” (2019) http://dx.doi.org/10.2760/901029
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14. “Auniversalplatformwithinternal
programminglanguage,sothateveryone
couldwriteanyapp”
[V. Buterin]
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Claudio Di Ciccio
From a peer-to-peer electronic cash system
to a programmable distributed environment

15. Smart Contracts
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•Smart Contracts in Ethereum
live in the Ethereum environment
execute a function when called
have direct control over their own
balance and key/value storage
exhibit a behaviourthat is fully
specified by their code

16. Expressive power of
smart contracts
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•Variants exist
•Solidityis a Turing-completelanguage
for the Ethereum blockchain
•Smart contracts can potentially run any
computable algorithm
Picture: https://doi.org/10.1093/ref:odnb/36578

17. A programmable distributed environment
Input encoded data
Smart Contract
Account
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Invoking a smart
contract function
Execution is not
externally
stoppable!

18. From high-level code to bytecode to bits and
bytes
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19. A programmable distributed environment
Input encoded data.
Smart Contract
Account
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New
Smart Contract
Account
New address
Smart contract code to be deployed
Invoking a smart
contract function
Deploying a new
smart contract
Execution is not
externally
stoppable!

20. 03/06/2024Claudio Di Ciccio
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Where are Smart Contracts
executed?
First on the mining nodes.
Then, potentially, on every node!
The polygraph machine

21. A programmable distributed environment
Input encoded data.
Smart Contract
Account
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New
Smart Contract
Account
New address
Smart contract code to be deployed
Invoking a smart
contract function
Deploying a new
smart contract
Execution is not
externally
stoppable!
Gas price (execution costs)
Gas price (execution costs)

22. Execution is not for free
(most of all, in public blockchains)
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Wood , “Ethereum: A secure decentralised generalised transaction ledger” (2014), https://ethereum.github.com/yellowpaper/pape r.pdf

23. Challenges about costs
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24. Price instability of cryptocurrency and gas prices
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ETH/EUR exchange Gas price on the Ropstentestnet

25. Cryptos and fiat money
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Image source: https://www.kbrillphotograp.top/products.aspx?cname=jlo+jenny+from+the+block+outfit&cid=140
Keep smart contracts
lean!
Only absolutely
needed instructions
should be in the
code.

26. The paradigm
Mainframe Terminal
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L: https://commons.wikimedia.org/wiki/File:SiemensHicom300_1200.jpg; R: https://commons.wikimedia.org/wiki/File:HP_2647A_term inal.jpg

27. Web 3.0 and
Decentralised applications (DApps)
27
03/06/2024Claudio Di Ciccio

28. Advantages and connection to processes
•Smart contracts → Programmability → Process rule enforcing
•Transactions → Asset transfer & function invocation → Process execution
•Distributed store →Data persistency → Process monitoring
•Ledger → Transaction ordering → Logging
•Hashing → Robustness → Secure storage
•Signatures → Authentication → Non-repudiability
•Consensus → Eventual consistency → Traceability
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Images: Left: https://doi.org/10.1145/3183367; right: https://www.dagstuhl.de/en/seminars/seminar-calendar/seminar-details/18332
Layer of trust
even in a
regime of
partial trust
among actors

29. Executing inter-organisational processes on the
Blockchain: A model-driven approach
D.C, Cecconi, A., Dumas, M., et al. (2019), “Blockchain support for collaborative business processes”
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30. Executing inter-organisational processes on the
Blockchain: A model-driven approach
Caterpillar Lorikeet
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ChorChain
D.C, Cecconi, Dumas et al. Blockchainsupport for collaborative business processes. InformatikSpektrumpp. 1–9 (May 2019)
López-Pintado, García-Bañuelos, Dumas, Weber. Caterpillar: A blockchain-based business process management system. In: BPM Demos. CEUR.ws, 2017.
Tran, Lu, Weber. Lorikeet: A Model-Driven Engineering Tool for Blockchain-Based Business Process Execution and Asset. In: BPM Demos. CEUR.ws, 2018.
Corradini, Marcelletti, Morichetta, Polini, Re, Tiezzi: Engineering Trustable and Auditable Choreography-based Systems Using Blockchain. ACM TMIS 13(3), 2022.

31. Tracking execution
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D.C. et al. Blockchain-Based Traceability of Inter-organisationalBusiness Processes. In: BMSD. Springer, 2018.
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32. Traceability
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D.C. et al. Blockchain-Based Traceability of Inter-organisationalBusiness Processes. In: BMSD. Springer, 2018.

33. From execution to ledgers
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Claudio Di Ciccio

34. Traceability
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https://www.sage.com/en-gb/blog/blockchain-traceability-supply-chain/ Accessed: 19/02/2020

35. From ledgers to time-ordered datasets
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36. From data sets to process mining and analytics
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37. Mining blockchain processes
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38. Mining blockchain processes
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39. Double spending
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0xA 0xB0xC
100 ¢10 ¢ 50 ¢
10 ¢ 140 ¢
90 ¢
50 ¢
Tx ID: 0xA90B
Tx ID: 0xA50CX

40. Double spending
41
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0xA 0xB0xC
100 ¢10 ¢ 50 ¢
90 ¢
Tx ID: 0xA90B
50 ¢
Tx ID: 0xA50C

41. Double spending
42
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0xA 0xB0xC
100 ¢10 ¢ 50 ¢
90 ¢
Tx ID: 0xA90B
50 ¢
Tx ID: 0xA50C
60 ¢ 50 ¢
X

42. On-chain vs off-chain
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Image source: https://www.kbrillphotograp.top/products.aspx?cname=jlo+jenny+from+the+block+outfit&cid=140
The broken link is
that blockchain
natively has no
control on or view of
off-chain objects

43. The problem
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DB

44. How about the real world?
Oracles: From on-chain to off-chain and vice versa
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Claudio Di Ciccio

45. The Oracle
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Foundational Oracle Patterns: Connecting Blockchain to the Off-Chain World. BPM (Blockchain and RPA Forum) 2020: 35 -51
DB

46. Etherisc
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47. Flight delay insurance:
the FlightDelayPayout contract
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Payout in case of
signalled problems
with the flight
Contact with the
off-chain world
Source: https://www.flickr.com/photos/michaelduxbury/5824469025

48. The Oracle
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Foundational Oracle Patterns: Connecting Blockchain to the Off-Chain World. BPM (Blockchain and RPA Forum) 2020: 35 -51
DB
ISO/TC 307, ISO/TR 2345: “[A] DLT Oracle[is a] servicethat updates a distributed
ledger using data from outsidethe distributed ledger system”. (2019)
Previous literature: oracles as off-chain information providers.
We see oraclesas a bridge
between the on-chain and off-chain worlds.

49. Oracle patterns: Overview
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Foundational Oracle Patterns: Connecting Blockchain to the Off-Chain World. BPM (Blockchain and RPA Forum) 2020: 35 -51
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50. Decentralisedoracles
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Enhancing Blockchain-Based Processes with Decentralized Oracles. In: BPM Blockchain and RPA Forum 2021, 102-118, Springer.
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51. Decentralisedoracles (example: pull-in)
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Enhancing Blockchain-Based Processes with Decentralized Oracles. In: BPM Blockchain and RPA Forum 2021, 102-118, Springer.
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52. Decentralisedoracles (example: pull-in)
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Enhancing Blockchain-Based Processes with Decentralized Oracles. In: BPM Blockchain and RPA Forum 2021, 102-118, Springer.
Credit institute 1
Decentralized
oracle
Credit institute 3
Credit institute 2
Smart
contract

53. About privity
•Albeit very costly, we could inject all the
information we need on-chain.
•Even if we were able to inject all the data
in the world on chain, would we like the
idea?
•“Privitystrives for limiting the sharing of
information within a contract to those
parties of a contract who have a
contractual need to know”
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Köpke, Franceschetti, Eder: Balancing Privity and Enforceability of BPM-Based Smart Contracts on Blockchains. BPM (Blockchain and CEE Forum) 2019: 87-102

54. 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)

55. … the whole network observes
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Scene from The Truman Show (1998). Image source: https://redeemingculture.com/film/drama/4106 -the-truman-show-empathy-and-reality

56. Ledger and secrecy
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Image source: https://www.kbrillphotograp.top/products.aspx?cname=jlo+jenny+from+the+block+outfit&cid=140
Every participant in
the blockchain
network can read the
data on the ledger
unless the platform
is private and
permissioned
Public
permissionless
platforms are more
robust and
guarantee non-
repudiability

57. Transaction information hiding via
homomorphic encryption
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Xu, Zhang, Zhu (2023). Regulation-Friendly Privacy-Preserving Blockchain Based onzk-SNARK. In: Advanced Information Systems Engineering Workshops.
CAiSE2023
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Coming next: High-Performance
Confidentially-Preserving Blockchain via
GPU-Accelerated Fully Homomorphic
Encryption(Guan, Qi, Shen, Wang,
Zhang and Cui)

58. Fix this image in your memory
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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
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59. Is this the same image?
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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
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60. 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

61. Business Process Model and Notation (BPMN)
collaboration diagram
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62 a n u fa ctu re r
Pr oduc tion or der
s et up
Ord e r p a rts
ill of mater ials
e ch a n i ca l p a rts s u p p l i e r
ill of mater ials
r ec eiv ed
El e ctro n i c p a rts s u p p l i e r
ill of mater ials
r ec eiv ed

62. The message, in clear
(as seen by the manufacturer)
03/06/2024Claudio Di Ciccio
630xfd9ffe3578a42d81c4684bd47e6575d9a8f10cc6dab984bd7e19ee0dbacb6287Hash:

63. The message
(as seen by external parties)
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640xfd9ffe3578a42d81c4684bd47e6575d9a8f10cc6dab984bd7e19ee0dbacb6287Hash:

64. The message
(as seen by the electronic parts supplier)
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650xfd9ffe3578a42d81c4684bd47e6575d9a8f10cc6dab984bd7e19ee0dbacb6287Hash:

65. The message
(as seen by the mechanical parts supplier)
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660xfd9ffe3578a42d81c4684bd47e6575d9a8f10cc6dab984bd7e19ee0dbacb6287Hash:

66. Hence the name: CAKE
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Image source: https://heriots.co.uk/products/pistachio
Thursday, June 6, 14:00: CAKE: Sharing
Slices of Confidential Data on
Blockchain(Maragone, Spina, D.C.,
Weber)

67. Ingredients
•Blockchain platform
•Smart contracts
•InterPlanetary File System (IPFS)
•Ciphertext-Policy (CP) Attribute-Based Encryption (ABE)
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68. CP-ABE
•Attribute-Based Encryption (ABE): type of public-key encryption
•Ciphertext-Policy ABE (CP):
We associate rolesand process instance IDwith attributes
(propositionalliterals)
Messages are associated with policies
(propositional formulae on attributes)
•Attributes:
14548487, Supplier, Electronics, Mechanics, Manufacturer
•Policy:
14548487 AND
(Manufacturer OR (Supplier AND Electronics))
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Process
instance ID
Roles

69. CAKE
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Icons: https://www.iconfinder.com/
PolicyPlaintext Ciphertext
Ciphertext Plaintext
Secret key
Attributes Secret key
1: ciphering
2: key generation
3: deciphering
0: pre-phase
Public
key (pk)
Master public
key (mpk)
pk
pk
Key pair
Key pair
pk
mpk
Given
Attribute certification

70. Phase 0: certification
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Attribute certifier
Address: 0x123
Attributes: 14548487, Manufacturer
Address: 0x456
Attributes: 14548487, Supplier, Electronics
Address: 0x789
Attributes: 14548487, Supplier, Mechanics
Smart Contract

71. Phase 1: ciphering
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72. Phase 1: ciphering
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73. Phase 2: key generation
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14548487, Manufacturer
14548487, Supplier, Electronics
14548487, Supplier, Mechanics
D: 2nN6…GCcZ
Dj: 4558…5+Qg
Djp: 8944….5949
D: A9BS…CnoO
Dj: OQEL…1207
Djp: hI2M…. lWBb
D: 1+8Ka…kaUd
Dj: feoH…7393
Djp: bJju…. NIGw
Key pair
Key pair
Key pair

74. Message policy example
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AttributesProcess instance (case id)

75. Phase 3: deciphering
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76. Phase 3: deciphering
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77. Focus
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14548487, Supplier, Mechanics
Why?

78. Q&A
•Why a certifier?
With signatures, you can prove that “you are you”
Without a certifier, you cannot prove that what you say is true
•Who forges the keys?
A delegated key manager
•One certifier, one key manager. What about decentralisation?
Right…
•Can you integrate your technique with a BPMS?
Not yet but…
03/06/2024Claudio Di Ciccio
Marangone, D.C:, Weber: Fine-Grained Data Access Control for Collaborative Process Execution on Blockchain. BPM (Blockchain and RPA Forum ) 2022: 51-67
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79. Room for improvement
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Marangone, D.C., Friolo, Nemmi, Venturi, Weber: MARTSIA: Enabling Data Confidentiality for Blockchain-based Process Execution (2023)
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Multi-Authority Approach to Transaction Systems for Interoperating Applications

80. The new architecture: MARTSIA
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Marangone, D.C., Friolo, Nemmi, Venturi, Weber: MARTSIA: Enabling Data Confidentiality for Blockchain-based Process Execution (2023)
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1. Key management 2. Data exchange0. Initialisation
Push-
inbound
oracle
Pull-
outbound
oracle

81. Integration with Caterpillar
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82. About the costs
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83. Why are prices in Gwei?
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ETH/EUR exchange Gas price on the Ropstentestnet

84. Open challenges
•Revoke access to data
•Let Smart Contracts use off-chain data via pull-inbound oracles
•Test with real-world multi-party business processes in production
•Extend the policy language with primitives for aggregating and
manipulating data
•…
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Friday, June 7, 14:00: Trusted Execution
Environment for Decentralized Process
Mining (Goretti, Basile, Barbaro, D.C.)

85. Open challenges at large
•Strike a balance between “smart-contracting” and off-chain
deployment of PAISs
•Define the interplay of Blockchain-as-a-Service for PAISs
•Build a standard communication format for blockchain-based inter-
organisational information exchange
•Establish guidelines for the use of blockchain technologies with and
within PAISs
•…
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Friday, June 7, 14:00: Trusted Execution
Environment for Decentralized Process
Mining (Goretti, Basile, Barbaro, D.C.)

86. “I’m still / I’m still /
Chaining from the
Block”
An Outlook of the Ongoing and Future Relationship
between Blockchain Technologies and Process-aware
Information Systems
Claudio Di Ciccio | https://diciccio.net/| [email protected]
Utrecht University, Netherlands
Picture: https://youtu.be/dly6p4Fu5TE?si=MTqzSi5KGLIZn3sr
Friday, June 7, 14:00: Trusted Execution
Environment for Decentralized Process
Mining (Goretti, Basile, Barbaro, D.C.)