From Collection to Analysis: A Blockchain Solution for Transparent and

Reliable Chain of Custody in the O&G Sector

Theo Caldas

1 a

, Ana Lara Mangeth

1 b

, Yang Ricardo Miranda

, Paulo Henrique Alves

1 c

Rafael Nasser

1 d

, Gustavo Robichez

, Gil Marcio Silva

and Fernando Pellon de Miranda

ECOA Institute, Pontiﬁcal Catholic University of Rio de Janeiro, RJ, Brazil

Petrobras, Rio de Janeiro, Brazil

{theocaldas, analara-mangeth, yang, ph.alves, nasser, robichez}@puc-rio.br, {gilmarcio, fmiranda}@petrobras.com.br

Keywords:

Chain of Custody, Blockchain, Smart Contracts, Oil Spil, Oiled Fauna.

Abstract:

The oil and gas (O&G) sector relies on a robust chain of custody mechanisms to ensure the transparency,

integrity, and traceability of materials and environmental evidence. Traditional custody systems often suffer

from inefﬁciencies, data fragmentation, and vulnerabilities to unauthorized alterations. This paper presents

Cust

odiaBR, a blockchain-based solution designed to enhance the registration and monitoring of oily waste

and oiled fauna samples collected during Petrobras’s Beach Monitoring Projects (Projetos de Monitoramento

de Praias - PMPs). Cust

odiaBR integrates real-time data from a centralized monitoring system and leverages

the Brazilian Blockchain Network (RBB) to provide a transparent, immutable, and auditable custody record.

The proposed system employs a hybrid on-chain/off-chain architecture, composed of ﬁve major components,

ensuring data integrity while preserving conﬁdentiality through cryptographic hash veriﬁcation. Through a

comparative analysis with existing blockchain-based forensic solutions, this study highlights the advantages

of public-permissioned blockchain in industrial applications, demonstrating how Cust

odiaBR can serve as a

model for digital chain of custody systems.

1 INTRODUCTION

The oil and gas (O&G) sector is characterized by

complex operations that require high levels of trace-

ability, transparency, and regulatory compliance. One

critical aspect of these operations is the chain of cus-

tody, which ensures the proper documentation and

tracking of materials, samples, and waste through-

out their lifecycle (Bullerdiek et al., 2025). Chain of

custody systems play a vital role in maintaining ac-

countability and preventing unauthorized alterations

or data loss. In particular, environmental monitor-

ing programs depend on reliable custody mechanisms

to track the collection, transportation, and analysis of

oily waste and oiled fauna resulting from oil spills.

Ensuring data integrity, transparency, and accessibil-

ity across multiple stakeholders is a key challenge

in these processes, requiring innovative technological

solutions.

https://orcid.org/0009-0003-3673-2692

https://orcid.org/0000-0003-1624-1645

https://orcid.org/0000-0002-0084-9157

https://orcid.org/0000-0002-6118-0151

Blockchain technology has emerged as a promis-

ing tool to enhance the reliability and auditability of

custody systems in various industries, including O&G

(Batista et al., 2023). Traditional document-based

recordkeeping is susceptible to manipulation, inef-

ﬁciencies, and inconsistencies between different or-

ganizations. By leveraging distributed ledger tech-

nology (DLT), blockchain introduces an immutable,

decentralized, and tamper-resistant approach to stor-

ing and verifying custody-related data. While public

blockchains provide high transparency, they present

scalability and cost limitations, making permissioned

blockchains a more suitable alternative for industry

applications that require controlled access and regu-

latory compliance.

In this context, the Brazilian Blockchain Net-

work (RBB) stands out as a government-led initia-

tive that enables secure, permissioned data registra-

tion for public and private organizations in Brazil.

RBB employs a modular architecture based on Hy-

perledger Besu, using Quorum Byzantine Fault Tol-

erant (QBFT) consensus mechanism to achieve high

performance with reduced energy consumption. The

network’s hybrid governance model, often referred to

410

Caldas, T., Mangeth, A. L., Miranda, Y. R., Alves, P. H., Nasser, R., Robichez, G., Silva, G. M. and Pellon de Miranda, F.

From Collection to Analysis: A Blockchain Solution for Transparent and Reliable Chain of Custody in the O&G Sector.

DOI: 10.5220/0013497600003929

Paper published under CC license (CC BY-NC-ND 4.0)

In Proceedings of the 27th International Conference on Enterprise Information Systems (ICEIS 2025) - Volume 1, pages 410-417

ISBN: 978-989-758-749-8; ISSN: 2184-4992

as public-permissioned, allows public read-access of

the ledger, while restricting write and validate oper-

ations to trusted authenticated parties. The network

topology, which includes validator, writer, and ob-

server nodes, allows for efﬁcient custody registration

while ensuring compliance with industry regulations.

This makes RBB a strong candidate for applications

that demand robust traceability, transparency, and col-

laboration across multiple institutions.

This work presents Cust

odiaBR, a blockchain-

based solution developed to enhance the chain of cus-

tody for oily waste and oiled fauna monitoring in

Beach Monitoring Projects (Projetos de Monitora-

mento de Praias - PMPs). The system is designed

to meet high industrial standards, as Petrobras acts

at the global-level O&G sector, particularly in off-

shore exploration and production, and plays a cru-

cial role in Brazil’s economy and the international

energy market. The full system-level architecture in-

cludes ﬁve integrated subsystems: (i) Backend Server

/ Database; (ii) GatewayBR Web3 Proxy; (iii) VIA

(Sample Integrity Veriﬁer) Frontend Application; (iv)

Self-hosted Dashboard; and (v) Self-hosted Block

Explorer. It integrates real-time data from Petro-

bras’s SIMBA API and registers key custody events

on RBB. It employs a hybrid on-chain/off-chain ar-

chitecture, where critical metadata are recorded on

the blockchain to ensure immutability, while more de-

tailed custody records are stored in secure off-chain

databases. This approach not only ensures data in-

tegrity and traceability but also addresses privacy con-

cerns by preventing the exposure of sensitive environ-

mental data.

This paper is structured as follows. Section 2 is fo-

cused on the concepts of chain of custody and public-

permissioned blockchains. Section 3 presents the re-

lated work and Section 4 details the Cust

odiaBR so-

lution. Finally, section 5 presents the conclusion and

future work.

2 BACKGROUND

2.1 Chain of Custody in O&G Sector

Chain of custody refers to the systematic recording

and accountability of custody, control, transfer, anal-

ysis, and disposition of an asset or evidence (Chopade

et al., 2019). The chain of custody establishes a clear

and veriﬁable pathway, demonstrating uninterrupted

control and handling of assets from their origin to

their ultimate destination. Ensuring accuracy in the

chain of custody is important to avoid unauthorized

access, tampering, or loss of assets and evidence. It

is fundamental in legal, forensic and regulatory envi-

ronments, as it ensures both the integrity and admis-

sibility of evidence during judicial proceedings.

This process involves documenting key details

such as date, time, location, individuals involved, and

changes in custody. To meet these objectives, chain of

custody protocols typically demand strict compliance

with established procedures, prioritizing the preserva-

tion of the integrity and authenticity of assets through-

out their lifecycle.

In the context of O&G, the chain of custody is also

of great signiﬁcance (Bullerdiek et al., 2025). In this

ﬁeld, effective control and traceability of materials,

oily waste, and evidence handled throughout opera-

tional stages are essential. Examples of chain of cus-

tody applications in O&G include the traceability of

oily waste, quality control of O&G samples, and fraud

prevention in logistic operations.

This work focuses on the registration of the chain

of custody for oily waste and oiled fauna result-

ing from oil spills, utilizing blockchain technology.

These items are identiﬁed within the scope of PMPs,

which oversee monitoring activities related to envi-

ronmental licensing and aim to assess the impact of

Petrobras’s exploration and production (E&P) activi-

ties on marine tetrapods, which include birds, turtles,

and marine mammals.

During beach monitoring, oily waste and oiled

fauna samples are collected directly on the beach,

where they are identiﬁed and stored for transfer to the

PMP support base. Subsequently, they are transported

to Petrobras laboratories for analysis. Thus, the sam-

ple follows a workﬂow comprising three main stages:

(i) collection and delivery, (ii) reception and registra-

tion, and (iii) analysis and conclusion. At each of

these stages, a speciﬁc system is used to record infor-

mation, since the sample changes environments and

custodians. In the ﬁrst stage, the Aquatic Biota Mon-

itoring Information System (Sistema de Informac¸

de Monitoramento da Biota Aqu

atica - SIMBA) sys-

tem is employed, whereas in stages 2 and 3, Petro-

bras’s laboratory information management system is

utilized.

Hence, for the chain of custody, it is crucial

that each handling step of the sample is thoroughly

recorded. Relevant data related to these samples in the

different stages include: the date and time they were

found, the latitude and longitude of the location where

they were collected, the name of the monitor respon-

sible for the collection, the name of the ﬁeld coor-

dinator who registered the sample, the sample num-

ber, the laboratory identiﬁer number, and the names

of the custodians responsible for the analysis. The

immutable blockchain registration of this set of infor-

From Collection to Analysis: A Blockchain Solution for Transparent and Reliable Chain of Custody in the O&G Sector

411

mation for each sample ensures the integrity, trans-

parency, and traceability of the collected evidence,

while also enabling the consultation of this data in

case an audit is required.

2.2 Governamental Permissioned

Blockchain

Blockchain governance is categorized into two dis-

tinct types: permissioned blockchains and permis-

sionless blockchains. A permissioned blockchain is

a DLT in which access to the network is restricted to

authorized participants. Unlike public blockchains,

which allow anyone to join and validate transac-

tions, permissioned blockchains require pre-approved

identities and speciﬁc governance mechanisms. This

structure enhances security, ensures compliance with

regulatory frameworks, and allows organizations to

tailor the blockchain’s architecture to speciﬁc oper-

ational needs. In the context of chain of custody, per-

missioned blockchains provide a controlled environ-

ment that ensures data integrity, transparency, and ac-

countability while maintaining conﬁdentiality where

necessary.

The primary differences between permissioned

and public blockchains lie in access control, per-

formance, cost, and consensus mechanisms. Pub-

lic blockchains, operate in a decentralized and trust-

less manner, leveraging mechanisms like Proof of

Work (PoW) or Proof of Stake (PoS) to validate

transactions. These consensus protocols often result

in higher computational costs and lower transaction

throughput due to their reliance on global validation

processes.

In contrast, permissioned blockchains employ

more efﬁcient consensus algorithms, such as Practi-

cal Byzantine Fault Tolerance (PBFT) or Raft, which

require fewer computational resources and provide

faster transaction ﬁnality. Additionally, permissioned

blockchains allow organizations to optimize network

governance, reducing operational costs while main-

taining robust security guarantees. In scenarios where

a chain of custody must be established, a permis-

sioned blockchain offers a more scalable and cost-

effective solution by enabling selective participants to

record data and faster transaction processing.

A relevant example of a permissioned-based

blockchain initiative is RBB. It is a government-led

initiative designed to provide a reliable and trans-

parent infrastructure for public institutions and pri-

vate entities in Brazil. It aims to improve the secu-

rity and traceability of digital records while promot-

ing interoperability between different organizations

(Miranda et al., 2023). It is often referred to as a

public-permissioned blockchain, since its governance

model keeps the security and efﬁciency qualities of a

permissioned network, through the usage of a Proof-

of-Authority consensus mechanism, while enabling

read-access to the general public. The network con-

sists of multiple node types, including validator nodes

responsible for consensus, writer nodes that submit

transactions, and observer nodes that allow read-only

access.

RBB employs Hyperledger Besu as its blockchain

protocol, leveraging an energy-efﬁcient consensus

mechanism such as QBFT. This setup enables high

throughput and low transaction costs while ensuring

the immutability of records. In the context of chain

of custody, the RBB stands out by offering a permis-

sioned and auditable infrastructure where evidence

records can be securely stored, preventing tamper-

ing and unauthorized modiﬁcations. Its governance

model ensures accountability while maintaining efﬁ-

ciency, making it a strong candidate for applications

that require rigorous data integrity standards.

3 RELATED WORK

This section provides an overview of the current state

of the art in digital innovations in the O&G sector re-

lated to the chain of custody ﬁeld. It particularly fo-

cuses on core industry activities, such as data trace-

ability, transparency, and forensic investigation. The

goal is to highlight the advancements and identify

possible gaps compared to our solution.

Zawoad and Hasan propose Faiot, a forensics-

aware ecosystem designed to integrate forensic capa-

bilities directly into IoT devices (Zawoad and Hasan,

2015). Their approach aims to ensure the integrity

and availability of digital evidence during investiga-

tions. In this sense, Cust

odiaBR operates at a broader

operational level by integrating data from multiple

centralized sources and registering relevant custody

data in a public-permissioned blockchain. This allows

Cust

odiaBR to achieve not only evidence integrity,

but also greater traceability across the chain of cus-

tody, while mitigating data exposure risks through a

hybrid on-chain/off-chain architecture.

Nelufule et al. propose an adaptive digital forensic

framework tailored to address challenges in Industry

4.0 and 5.0. Their framework emphasizes the adapta-

tion of forensic methodologies to evolving technolog-

ical complexities (Nelufule et al., 2024). In contrast,

Cust

odiaBR goes beyond forensic adaptation by oper-

ationalizing blockchain in a speciﬁc industrial appli-

cation in the O&G sector. Cust

odiaBR integrates real-

time data from Petrobras’s SIMBA API and ensures

ICEIS 2025 - 27th International Conference on Enterprise Information Systems

412

reliable custody evidence through blockchain, provid-

ing end-to-end transparency in custody systems.

Kumar et al. introduce CourtSafe, a blockchain-

based system for the secure storage and manage-

ment of legal records (Kumar et al., 2024). While

their solution is tailored for legal record management,

Cust

odiaBR applies blockchain in a dynamic indus-

trial context with real-time operational data. Addi-

tionally, Cust

odiaBR leverages its modular architec-

ture, including GatewayBR for blockchain abstraction

and a hash-based data integrity mechanism, to efﬁ-

ciently handle high-volume data while ensuring trace-

ability.

Pawar et al. explore the use of graph-based neu-

ral networks combined with blockchain to enhance

forensic investigations (Pawar et al., 2024). Their

work focuses on improving anomaly detection and

evidence analysis. Cust

odiaBR, on the other hand,

ensures data integrity and transparency in a chain of

custody speciﬁc to the O&G industry. Its practical

integration of blockchain technology, supported by

a modular and ﬂexible infrastructure such as Gate-

wayBR, addresses real-world challenges like regu-

latory compliance and blockchain interoperability,

which are not directly addressed in the solution pro-

posed by Pawar et al.

Rani et al. present a secure digital evidence

preservation system for IoT-enabled smart envi-

ronments using IPFS (InterPlanetary File System),

blockchain, and smart contracts (Rani et al., 2025).

Their solution focuses on ensuring the immutabil-

ity and traceability of digital evidence. Cust

odiaBR

differentiates itself by implementing a modular solu-

tion that includes GatewayBR, that supports multiple

EVM-compatible networks. Moreover, Cust

odiaBR

addresses privacy and computational efﬁciency con-

cerns by storing sensitive data off-chain and ensuring

data integrity using cryptographic hashes, making it

more compliant with regulations such as the Brazilian

General Data Protection Law (Lei Geral de Protec¸

de Dados Pessoais - LGPD).

These studies illustrate the transition from conven-

tional document-centric methodologies to data-driven

approaches facilitated by blockchain technology. In

this context, solutions like Cust

odiaBR serve as key

milestones in enabling the structured distribution of

complex operational data. Moreover, they enhance

coordination in multiparty environments by leverag-

ing blockchain’s immutability and decentralized trust

model, ensuring greater transparency, efﬁciency, and

reliability in custody-related processes.

4 DECENTRALIZED CHAIN OF

CUSTODY SOLUTION

4.1 Architecture

Cust

odiaBR is a solution designed to leverage

blockchain technology to promote traceability, trans-

parency and integrity of operational data across cus-

tody systems in the O&G sector. It solves the task of

collecting data from multiple centralized sources and

registering relevant content in a public-permissioned

blockchain, creating trustworthy and publicly avail-

able custody evidence while protecting sensitive data

from undesired exposure.

In this research, the deployed Cust

odiaBR solu-

tion extracts sample-based data, e.g., geographic lo-

cation of an oil leakage, from Petrobras SIMBA pub-

lic REST API and writes it out to RBB via EVM-

compatible smart contract. The full system-level ar-

chitecture of Cust

odiaBR is the result of the inte-

gration of ﬁve subsystems, deployed as individual

Docker containers:

• Backend Server / Database;

• GatewayBR Web3-Proxy Server;

• VIA Frontend Application;

• Self-hosted Dashboard; and

• Self-hosted Block Explorer.

Figure 1 presents the data ﬂow diagram between

these main components, regarding Petrobras DMZ in-

frastructure. The diagram also depicts the SIMBA

data source, RBB blockchain service, and public ex-

ternal access.

[Backend Server]. It is a Java Quarkus application

that schedules background routines to request REST-

ful data from the provided data sources and persists

them in a uniﬁed PostgreSQL Database. The latter is

of utter importance as different data sources may con-

tain sample data at different stages of custody con-

trol. The server also ﬁres routines to send a cluster

of collected data to the RBB blockchain service by

smart contract transaction call. This request is inter-

mediated by GatewayBR Web3-Proxy Server, which

will be described later on. The server provides sample

data to the VIA Frontend Application through public

REST API.

[GatewayBR]. It is a middleware designed to opti-

mize communication between the application layer

and blockchain service providers, working as a Web3

proxy to client applications. The developed server is

a NestJS application that abstracts the complexities

of blockchain networks, providing a REST API inter-

face for deploying smart contracts and sending trans-

From Collection to Analysis: A Blockchain Solution for Transparent and Reliable Chain of Custody in the O&G Sector

413

Figure 1: Cust

odiaBR system-level architecture.

actions. As blockchain technology evolves and exe-

cution and consensus protocols are replaced, the need

for an intermediate layer architecture is crucial, espe-

cially because the application-to-network relation is

many-to-many.

In fact, blockchain networks that use the same

technology should be switchable in both the devel-

opment and production application phases. Manually

implementing these changes at the application level

not only increases code cost, but also reveals secu-

rity complexity on permissioned networks. More-

over, this “Plug and Play” approach allows ﬂexibil-

ity in choosing blockchain service providers, reduc-

ing system coupling and promoting a more resilient

and adaptable infrastructure.

GatewayBR REST API supports blockchain ser-

vice providers operating on either Hyperledger Besu

or Hyperledger Fabric platforms. In case of

a provider based on Besu ETH-Client, such as

the RBB network, the API expects the provider

to be registered via /evm-besu/chains POST

call. The client application informs the chain

ID, a network alias and the URL to a valid

JSON-HTTP-RPC node to receive further requests.

Then, GatewayBR is able to process transactions

by /evm-besu/chains/{chainId}/transactions

POST call, which should include the chain ID, the

deployed contract address, the command name (e.g.,

registerCustodyEvent) and the encoded call data.

Also, it expects the client application to generate a

UUID for the created transaction, facilitating later

identiﬁcation of the ﬁnal status and the recipe that

may contain logs from smart contract execution,

block number and public transaction ID.

In the context of Cust

odiaBR, GatewayBR

receives API calls from the Backend Server

and transfers them to a registered RBB node,

which interacts with the smart contract method

registerCustodyEvent to persist sample data. The

requests must include the chain ID linked to the

previously registered network node.

[Frontend Application]. VIA is a NextJS web server

that provides a solution for verifying data integrity in

the chain of custody. It improves transparency and re-

liability in sample data audit and surpasses limitations

imposed by data protection and computational perfor-

mance, which excludes certain ﬁelds from its record

on the blockchain (off-chain data). To mitigate vul-

nerabilities in off-chain data, the solution uses an ap-

proach based on cryptographic hashes, which enables

fast validation of the collected data without exposing

sensitive details, ensuring a more accessible, secure

and efﬁcient audit process. The VIA Frontend Appli-

cation makes requests to the Backend Server through

its provided REST API.

[Dashboard]. It is a Metabase

distribution that

mirrors Cust

odiaBR Backend’s Database and enables

user-friendly creation of interactive dashboards and

custom queries. This improves sample data analyt-

ics and traceability, exposing relations between data

from multiple sources.

[Block Explorer]. It is a Blockscout

instance, a

block explorer service that enables transaction visu-

alization of veriﬁed Solidity smart contracts, which

was shown to be very helpful in the audit process.

The service reads validated block information directly

from public RBB network observer nodes, promoting

transparent access through its web interface.

4.2 Data Source

Cust

odiaBR is designed to receive data from multiple

data sources. However, the deployed version of the

system was restrictively built upon Petrobras project

for monitoring beaches along the Southeastern and

Northeastern coast of Brazil. The objective is to eval-

uate possible interferences of Petrobras activities in

the lifespan of aquatic and bird species located nearby

oil offshore platforms.

Metabase - https://www.metabase.com/

Blockscout - https://www.blockscout.com/

ICEIS 2025 - 27th International Conference on Enterprise Information Systems

414

As one of the many environmental transparency

initiatives from Petrobras, data entries in Petro-

bras PMP are of public interest. The registered

data is public-available through SIMBA, which of-

fers, alongside its web application

a public non-

authenticated REST API. It supports a single endpoint

with multiple query parameters, retrieving sample oc-

currence data in XML format.

Cust

odiaBR Backend Server is a client of SIMBA

public API, scheduling routines to fetch sample

data within a date range. The query parameters

start_date and end_date expose this ﬁlter option.

To request data for a speciﬁc sample occurrence, it

is possible to enter a record_number value, which

refers to the organismID associated with that same

sample. Other data ﬁlter options are listed in SIMBA

ofﬁcial documentation

For every fetched sample occurrence, there is an

XML response, which contains a cluster of domain-

related data, such as location, date and observations

of the occurrence, as well as the name of the institu-

tion and the employee responsible for its registry. In

case the occurrence refers to a dead or injured animal

organism, data related to its taxonomy and life stage

are also reported. Most retrieved occurrences also in-

clude measurement values of the sample.

Therefore, the ultimate goal of the deployed

Cust

odiaBR blockchain solution is to guarantee the

integrity of obtained SIMBA data in a transparent

manner. This is key in custody control because, as

shown in the mapped process mentioned in Section

2.1, those reports and pieces of evidence are trans-

ferred back and forth to other systems and labora-

tories. The blockchain layer of Cust

odiaBR acts as

a shared source of truth between partners, since any

adulteration of the collected data must be easily au-

dited and noticed, so to mitigate inconsistencies in the

chain of custody.

4.3 Blockchain Data Record

Cust

odiaBR blockchain layer, supported by Gate-

wayBR, is adaptable to handle migrations between

blockchain service providers. However, it is limited

to EVM-compatible (Ethereum Client) providers op-

erating under Hyperledger Besu. This design choice

concerns the use of publicly readable decentralized

ledgers, such as the RBB network, and the record-

ing of sample data by transactions to smart contracts

written in Solidity.

SIMBA - https://simba.petrobras.com.br/simba/web/

SIMBA Documentation - https://simba.petrobras.com.

br/simba/web/occurrences/doc

The smart contract should be structured in a non-

cost-expensive way. Although RBB’s underlying con-

sensus mechanism is QBFT, known to be a low-

computational Proof-of-Authority option for permis-

sioned networks, any unnecessary data storage rep-

resents a performance reduction of the block valida-

tion ﬂow. It would be unfeasible to record the many

dozens of data ﬁelds for every fetched sample.

Another baseline aspect of smart contract devel-

opment that should be considered is not exposing

any personal/sensitive data since blockchain is an im-

mutable database. Brazil’s regulations on the collec-

tion, storage, and processing of private digital data are

determined by LGPD, which currently does not con-

tain a law that covers blockchain use cases.

Regarding both aspects, as mentioned before, the

solution is to split the dataset into two categories:

on-chain and off-chain data. In this context, on-

chain data refers to a minimal cluster of values, for

every fetched sample, that are written in the block

record. This includes SIMBA sample identiﬁers - for

instance, organismID and measurementID - and a

calculated hash string of the entire XML response ob-

ject, to preserve the integrity of the collected data as

a whole. On the other hand, off-chain data are val-

ues excluded from the blockchain layer and stored in

a secure database. It contains the majority of SIMBA

API response ﬁelds.

The restriction of the values written on the

blockchain may decrease the total transparency of on-

chain data. To avoid that, off-chain data is stored in

the Cust

odiaBR local Database and, then, displayed

through the Cust

odiaBR Dashboard system, which

aggregates all data fetched from SIMBA and links

back to the blockchain record via transaction ID. That

is, the solution depends on both on-chain and off-

chain data, as the former guarantees the integrity of

the latter, and the latter promotes transparency to the

former.

4.4 Dashboard

The Cust

odiaBR Dashboard is a self-hosted Metabase

service and has two main objectives: (i) to generate

metrics and graphical visualizations of sample dis-

placements; and (ii) to provide a single view that con-

solidates the core data of the entire chain of custody

for a given sample, which includes both on-chain and

off-chain stored data. The Dashboard is designed to

receive, through database connection, data from var-

ious data sources involved in the custody control of

the evidence and to generate different types of visu-

alizations and analyses that may be relevant for diag-

nosis. An example of graphical visualization is the

From Collection to Analysis: A Blockchain Solution for Transparent and Reliable Chain of Custody in the O&G Sector

415

number of samples collected on a speciﬁc beach, ﬁl-

tered by time period, and the names of who monitored

this place.

The Dashboard enhances the organization and vi-

sualization of data obtained from different systems

(e.g., Petrobras’s SIMBA API) on a single timeline.

This includes data on all stages the sample has under-

gone (collection, registration, and analysis) and the

custodians involved, as well as the status of the evi-

dence at the time of access.

The view is fully customizable and can be ad-

justed to increase or decrease the level of data detail

displayed. Filters can also be applied to facilitate user

navigation. For every sample record, the view also

links to the Block Explorer page on which its on-chain

data was recorded, and displays a blockchain status

value to identify if has been successfully recorded on

the blockchain or remain unregistered.

The custom Dashboard view innovates by consol-

idating all the information in one place, enhancing

transparency regarding the evidence chain of custody

and facilitating control and accountability.

4.5 Integrity Veriﬁer

Verifying the integrity of sample data is a core princi-

ple of Cust

odiaBR, ensuring a transparent audit work-

ﬂow for the chain of custody. A key aspect of this pro-

cess is the hash-based approach, in which the server

records the hash string of the original collected data

on the blockchain.

The Block Explorer web service allows public

access to blockchain data, enhancing transparency

through direct access to the network ledger. Once the

deployed Solidity smart contract is veriﬁed, users can

search for a transaction ID to ﬁnd the recorded hash

of a sample, calculated when it was retrieved from the

Backend Server.

The audit workﬂow involves refetching the sample

data from its original source, such as making a request

to the SIMBA API using the sample’s organismID,

and manually recalculating its hash. If the recalcu-

lated hash matches the one stored on-chain, the data

remains unchanged. Otherwise, it indicates that the

data has been altered at the source.

Although the described steps illustrate a valid in-

tegrity veriﬁcation process, they raise two main con-

cerns that may affect the audit workﬂow effective-

ness. Firstly, regarding Petrobras’ general public in-

terest, most users experience readability difﬁculties

when accessing low-level block explorer data. The

system should output with conﬁdence that a said clus-

ter of data is reliable without the user’s need to know

blockchain-related concepts, such as validated blocks,

transactions, smart contracts, log events, and so forth.

This kind of abstraction can be achieved by a custom

user-friendly GUI.

The second issue relates to the fact that hash calcu-

lations are highly sensitive to any change in its input.

For a valid hash comparison, the digital artifact being

veriﬁed must be structurally identical to the one stored

on-chain. Any digital modiﬁcation, at the bit level,

will produce a different hash, regardless of whether it

alters the meaning of the data itself. This sensitivity

makes user-driven hash calculations prone to errors

and incorrect conclusions. The system should be able

to mitigate these inconsistencies by automatically re-

turning the valid hash string of the refetched original

data.

The Cust

odiaBR VIA Frontend Application sim-

pliﬁes integrity veriﬁcation with an intuitive web in-

terface, as depicted in Figure 2. Users provide the

sample data and receive an instant hash comparison

result. The deployed application processes XML re-

sponses from the SIMBA API and enhances the audit

workﬂow. If data modiﬁcation is suspected, the user

retrieves the organismID from the Dashboard and re-

quests the original XML ﬁle from the SIMBA public

API using this ID. The XML input data can be man-

ually entered into the web interface or uploaded as a

ﬁle. The application immediately calculates the hash

on the client side using the SHA-256 function.

The system then detects the sample identiﬁer and

requests the on-chain hash from the Backend Server.

The application displays the ﬁnal comparison mes-

sage and the two hash values: one from the user-

provided XML and the other from the blockchain. If

the hashes match, the data is considered unchanged.

Otherwise, modiﬁcations have occurred between the

original registration and retrieval.

5 CONCLUSION AND FUTURE

WORK

This paper explored the application of public-

permissioned blockchain technology to enhance chain

of custody processes in the O&G sector, particularly

in the context of environmental monitoring. By in-

tegrating RBB as blockchain infrastructure with ex-

isting digital systems, the proposed solution ensures

data transparency, integrity, and traceability, enabling

reliable custody records. The hybrid on-chain/off-

chain architecture avoids exposing sensible recorded

data while maintaining the immutability of custody

records.

The future work relies on expanding the scope of

blockchain integration beyond environmental custody

ICEIS 2025 - 27th International Conference on Enterprise Information Systems

416

Figure 2: Sequence diagram of the audit workﬂow.

to include logistics, asset management, and regulatory

compliance frameworks in O&G operations. Enhanc-

ing smart contract automation for custody validation,

anomaly alert mechanisms, and integration with IoT-

enabled tracking devices could further improve sys-

tem efﬁciency and data reliability.

Additionally, the next step should focus on inter-

operability between multiple blockchain networks, to

enable cross-organizational data exchange while pre-

serving privacy and security. This includes exploring

zero-knowledge proofs (ZKPs) and conﬁdential com-

puting to enhance data conﬁdentiality in blockchain-

based custody records.

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