PrivyCycle: The Bold Privacy Push Born From a Berlin Stage Clash

From ETHCC Hackathon to Berlin Spotlight: The Birth of a Movement

Forget the usual buzz of hackathon laptops! PrivyCycle's spark ignited under the blazing Berlin summer stage lights in June 2025. Picture this: d/acc Berlin, a crowd buzzing with Ethereum's sharpest minds, and Migle Rakitaite from Wxmen Web3Privacy Now stepping up to the plate, confronting none other than Vitalik Buterin himself. The air was electric as Rakitaite and her privacy posse threw down the gauntlet: "Why's the Ethereum Foundation dragging its feet on funding crypto-native solutions for sensitive health data, like period tracking on the blockchain?" That moment? Pure fire. It's where PrivyCycle's seeds were planted, right there in the heat of the debate.

It wasn't just talk. In the U.S., with abortion becoming a crime in several states, period-tracking apps turned into ticking time bombs. Data from big names like Flo and Clue got dragged into courtrooms, while these apps claimed privacy but sold user data to the highest bidder. The gap between what they promised and what they delivered? Wider than the Grand Canyon.

ETHGlobal CannesCC Hackathon: Where PrivyCycle Took Shape

Fast forward to the ETHGlobal CannesCC hackathon in 2025, and Rakitaite rallied the troops from TACo.build, Vialabs.io, 0g.ai, and Waku/Logos. Their mission? Craft a crypto-native alternative to the privacy disaster that is current period tracking apps. Enter PrivyCycle, smashing into the top 10 out of 334 entries at ETHCC and snagging three sponsor prizes. It's raw, it's a proof-of-concept, but it's raising big questions: Can Ethereum really step up for privacy-first apps beyond just DeFi and token swaps?

Zero-knowledge cryptography (ZK) was the go-to answer. Imagine proving to your doc that your cycle's been on point for six months without spilling the beans on dates or symptoms. Sounds slick, right? But here's the real talk: ZK on Ethereum is still in diapers. "DeFi zk" is miles ahead, while privacy tools for messy, ongoing data like menstrual logs? They're lagging big time. zk-SNARKs cost a fortune, Layer-2s scatter data all over, and off-chain storage like IPFS? It's a security wild west.

PrivyCycle hacked together what was available, leaning on Privy.io, Zurcuit, and 0g.ai's tech. Rakitaite demoed how users could log symptoms, encrypt data on their device, stash it on IPFS, and share it securely using threshold keys. Cool, right? But hold up—even the AI features got privacy red flags waving. Rakitaite cracked a joke about the app suggesting chocolate and flowers, but any AI dishing out personalized advice, even 'anonymized,' is sniffing around your data. Without open-source models or audits? It's all smoke and mirrors.

They also threw in options to export encrypted files for doctors and a dashboard for AI health insights. But let's keep it real: Most healthcare providers can't handle zk-protected records yet. The idea of taking your data anywhere you want? Only works if someone's ready to take it.

And the money talk? Shaky at best. Ryan Caruso from Threshold threw out a $10 billion figure for menstrual tracking apps by 2034, but that's lumping in everything from wearables to telehealth. Actual app revenues? A big question mark. Flo and Clue keep their cards close to the chest, especially when it comes to how they make their bucks off your data.

The risk? It's real. Flo got caught sharing sensitive data in 2021, and in today's post-Dobbs world, reproductive health data is a political grenade.

So why does PrivyCycle matter? Not because it's perfect, but because it shines a spotlight on what Ethereum's missing: Solid, scalable, decentralized privacy tools for our most personal data. Their roadmap? Better access control and data sharing, all end-to-end encrypted and decentralized using TACo. That's a promise that hit different in Paris than it did in Berlin.

The truth? Ethereum's been kicking the privacy can down the road. While DeFi's been getting all the zk love, apps for medical, identity, and social data? They've been left in the dust.

PrivyCycle isn't the final answer. It's a wake-up call. If Ethereum wants to level up from just moving money to being the backbone of our social lives, it's gotta get serious about end-to-end encryption and zero-knowledge privacy for non-financial data—not just in hackathon demos, but in the core of what it does.

As Rakitaite told the ETHCC crowd, with a fierce determination in her voice:

"On the first day of my daughter's period, I want to give her this. So she can manage her fertility with ease and confidence."