Fhenix Launches Fhenix402, Bringing Private Micropayments to Base’s x402 Standard
Miami, USA, Florida, December 17th, 2025, Chainwire
Fhenix has released Fhenix402, a one-day experimental build that marks the first-ever private version of Base’s emerging x402 payment protocol. Built using Fhenix’s CoFHE technology, the prototype demonstrates how fully encrypted transactions can make onchain micropayments private, composable, and usable — without revealing amounts to observers or block explorers.
These two announcements together highlight a turning point for Web3 privacy infrastructure: the need for a universally accepted taxonomy and the emergence of practical, real-world applications built on advanced cryptography.
Why Privacy Standards Matter Now
As Ethereum scaling matures and transaction costs fall, the industry’s bottleneck has shifted from throughput to privacy. Enterprises across payments, healthcare, AI, and finance require encrypted computation and confidential settlement — yet the ecosystem still lacks a clear way to assess competing solutions.
Borrowing from the impact of rollup stages on Layer-2 development, Fhenix’s Privacy Stages framework introduces a shared vocabulary and testable methodology to answer one core question: Who can decrypt your data?
“Progress accelerates when we share benchmarks,” said Guy Zyskind, MIT PhD in Cryptography and Founder of Fhenix. “Privacy Stages give developers, enterprises, and regulators the first objective way to evaluate blockchain privacy — and a roadmap to achieve true global confidentiality.”
The Four Privacy Stages
The framework categorizes privacy systems according to their cryptographic guarantees and real-world resilience:
Stage 0 — TEE-Only (“Trust the Box”)
Fast, but privacy collapses if the enclave is compromised.
Stage 1 — Pure Cryptography With Training Wheels
FHE/MPC improves security, but trust assumptions remain fragile without decentralized operators or additional safeguards.
Stage 2 — Blocking Quorum + Defense-in-Depth
The practical gold standard: distributed key generation, independent operators, optional TEEs, permissionless participation, and economic incentives. Breaking privacy requires either a major cryptographic failure or massive collusion.
Stage ℵ (Aleph) — Indistinguishable Obfuscation
A theoretical end-state where programs themselves become vaults. Not yet practical, but a north star for the industry.
This classification provides measurable criteria for builders, investors, and enterprises evaluating privacy tech — a step toward aligning ecosystem development and raising the bar for security.
Fhenix402: A Private Version of x402 Built in Just One Day
To test the boundaries of its CoFHE technology and FHERC20 token standard, Fhenix’s engineering team built Fhenix402 — a private version of Base’s emerging x402 micropayment protocol.
x402 introduces a long-awaited web primitive: HTTP 402 “Payment Required” as a real, universal micropayment layer. But in its current form, every payment is public.
Using CoFHE, Fhenix added privacy.
In just one day, the team deployed Fhenix402 on Base Sepolia, demonstrating payments where no one — not users, not block explorers — can see the real transaction amounts. Only encrypted values appear onchain, while wallets show directional updates without revealing specifics.
Two real transactions ($0.10 and $4.02) appear identical on Base Sepolia — indistinguishable to observers.
“You can’t tell which is which — and that’s exactly the point,” said Zyskind. “We built something that wasn’t supposed to be possible yet: private payments that are fast, composable, and intuitive.”
What Private Micropayments Unlock
The impact extends far beyond content access:
- Confidential subscriptions
- Private tip jars and donations
- Sealed-bid auctions
- Anonymous pay-per-use APIs
- Enterprise-grade private business intelligence
- Fraud detection on encrypted data
- Privacy-preserving AI and agentic workflows
This combination — programmability (Ethereum), access (Base), and confidentiality (FHE) — represents the missing layer of Web3 payments.
A Glimpse Into the Future of Encrypted Finance
The Fhenix402 experiment revealed gaps in today’s privacy infrastructure, including encrypted approvals, gas-efficient FHE operations, and user-friendly interfaces. Fhenix is actively addressing these gaps inside its CoFHE sandbox, building tools and standards to operationalize private onchain computation at scale.
“We’re at a true inflection point,” said Zyskind. “Circle, Stripe, and global enterprises are moving into blockchain payments. Privacy isn’t optional anymore — it’s the requirement that will make open payments viable.”
About Fhenix
Fhenix is a research and development company pioneering encrypted smart contracts with fully homomorphic encryption (FHE). Starting with a laser focus on Private DeFi, Fhenix is building the infrastructure to bring FHE everywhere — empowering developers, institutions, and users to create and use financial applications without sacrificing confidentiality or composability. Users can learn more at www.fhenix.io.