In Greek mythology, Harpocrates is the god of silence and well-kept secrets. In the digital world, protecting secrets — or rather, sensitive data — has become one of the key challenges in projects like DREX.
How can we ensure that sensitive data isn’t exposed in a programmable, auditable, and interoperable environment?
This challenge lies at the heart of the so-called “Drex trilemma”, which attempts to reconcile privacy, programmability, and composability — three pillars that rarely coexist in balance within distributed systems.
In the first phase of the DREX pilot, privacy architectures were validated by the Central Bank. All of them relied on different forms of zero-knowledge proofs (ZKPs), with variations involving segregated layers, parallel ledgers, and compatibility with the EVM. None of them, however, managed to offer a solution that balanced the three elements of the trilemma without adding excessive technical overhead or compromising auditability. The Central Bank acknowledged the progress but left the field open for new proposals.
And it’s in this space that Harpo emerges.
Developed by the SFCoop consortium — formed by Brazil’s cooperative systems Sicoob, Sicredi, Unicred, Cresol, and Ailos — Harpo is more than just a technical solution. It represents a movement by Brazilian credit unions to ensure that DREX is not merely a project of the big institutions. The solution is open source and was built with the goal of being robust enough to protect sensitive data, while also simple enough to be adopted by smaller players in the ecosystem.
Harpo aims to work natively with DREX smart contracts, without the need for additional tools. This matters not only from a technical standpoint but also for business: reducing complexity expands the entry door for those wanting to participate in the DREX ecosystem — especially the smaller ones.
The involvement of credit unions also strengthens a vision of a more plural financial system. With more than 15 million members in Brazil, these institutions already play a major role in the country’s financial inclusion.
In the DREX pilot, Harpo will be validated in a real estate tokenization use case, alongside Banco do Brasil, Caixa Econômica Federal, and ONR (the national real estate registry operator). But the proposal can go even further: if successful, it may become a viable standard for the privacy layer of Brazil’s future digital currency.
What’s at stake here is not just data protection, but the design of an ecosystem that is truly inclusive and scalable.
Solutions like Harpo could be the key for DREX to move forward. Let’s keep an eye on it!