Mist.cash - Ramp

MIST is private Venmo for crypto—except users don't even know they're on blockchain. Seamless payments with full self-custody and compliance. Just send and receive "money"—whatever it means to you.

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MIST is private Venmo for crypto—except users don't even know they're on blockchain.

Private payments were already working on MIST before the hackathon. During the hackathon, we accomplished two major goals that move us closer to real-world adoption:

Video Goal 1: [MOBILE] ZK Offramp - https://youtube.com/shorts/1zK-X_UBsdI

Video Goal 2: [DESKTOP] Seek and Hide - https://youtu.be/FRnkwotJZ4o

🔥 Goal 1: Implemented ZK OffRamp

We integrated liquidity provider APIs and built an offramp on top of MIST's privacy infrastructure.

🌟 Mist Ramp - Bridging DeFi to Mobile Money

Seamlessly convert your USDC to Kenyan Shillings with instant M-Pesa delivery

Mist Ramp brings privacy-preserving crypto-to-fiat conversion to East Africa. Users convert USDC holdings directly into Kenyan Shillings delivered instantly to their M-Pesa mobile money accounts. Built on lightning-fast blockchain with sub-second confirmations, Mist Ramp eliminates friction between decentralized finance and traditional mobile money systems.

🚀 Why Mist Ramp?

  • Instant Settlements: Convert USDC to KES and receive funds in your M-Pesa wallet within one minute
  • Zero Hassle: No KYC for small amounts, no bank accounts required—just your phone number
  • Competitive Rates: Real-time exchange rates with transparent pricing
  • Secure & Private: Powered by the MIST protocol's privacy guarantees
  • Mobile-First: Designed for the African mobile money ecosystem

Beyond Kenya: Proving the Architecture

We've had numerous Fintech partners interested in integrating MIST's privacy layer into their platforms. Despite extensive architecture discussions and whiteboard sessions, integration remained challenging. The cost model, security assumptions, and architectural complexity created uncertainty—we were essentially asking partners to be guinea pigs testing unproven infrastructure with their users' money.

Mist Ramp solves this. By building a complete, working offramp in production, we:

  • Prove the architecture works in the wild
  • Identify and fix real-world edge cases
  • Demonstrate security and reliability to potential partners
  • Provide a reference implementation for future integrations

This isn't just about Kenya—it's about validating MIST's architecture for global Fintech partnerships.

🎭 Goal 2: Built Full Seek and Hide Protocol

Spec: https://gist.github.com/shramee/2819b168d2db9d576fa6d5cff1cdb353

We implemented a novel privacy primitive that solves fundamental problems plaguing traditional mixers.

The Problem with Traditional Privacy Mixers

Traditional privacy mixers allow senders to hide assets in a contract and recipients to seek and withdraw them using zero-knowledge proofs. Most mixers require fixed denominations (e.g., 1 ETH or 10 ETH), which limits flexibility and fragments anonymity pools, weakening privacy.

The obvious solution is flexible amounts—but this creates worse problems:

1. Amount Correlation Attacks

When you deposit a unique amount (e.g., 7.3 ETH) and later withdraw exactly 7.3 ETH, blockchain observers can trivially correlate these transactions, completely breaking privacy. Your deposit amount fingerprints your withdrawal.

2. Forced On-Chain Exposure

To send funds to another recipient, you must first withdraw your full balance (exposing it on-chain), then make a new deposit. This creates multiple correlation points and unnecessary public transactions.

These problems exist because traditional mixers only support two operations:

  1. Hide: Deposit assets and update merkle tree
  2. Seek: Prove merkle membership of hidden transaction and withdraw it

🚀 Our Solution: Seek and Hide

We introduce a new operation: Seek and Hide. Within a single ZK proof, users can:

  • Seek their hidden transaction
  • Withdraw any amount (including zero)
  • Hide the remaining balance in a new transaction for themselves or another recipient

This revolutionizes private transactions by solving both fundamental problems while allowing complete amount flexibility:

🔍 Seek Phase - Partial Withdrawals

Withdraw only what you need. Amount correlation is broken because your withdrawal doesn't match your deposit.

🎭 Hide Phase - Private Re-Wrapping

The remaining balance is privately re-wrapped into a new transaction, which can be addressed to yourself or forwarded to another recipient—all within the same proof.

Key Benefits:

  • ✅ No amount correlation attacks
  • ✅ No forced on-chain exposure for transfers
  • ✅ Flexible amounts with full privacy
  • ✅ Gas-efficient single-proof operation
  • ✅ Forward funds privately without withdrawing

The seeking, partial withdrawal, and re-wrapping all happen within the same ZK proof, minimizing gas costs and on-chain exposure.

What We Shipped

  1. Production-ready ZK offramp with M-Pesa integration for the East African market
  2. Novel Seek and Hide protocol solving fundamental privacy mixer limitations
  3. Reference architecture proving MIST can support real-world Fintech integrations
  4. MIST SDK v0.2.beta - v0.2.2 for onboarding to MIST
  5. Offramp implementation Open sourced implementation for a ZK offramp with MIST

MIST isn't just theory anymore—it's working infrastructure ready for the next billion users (soon™️).

What's next

  1. Optimising ZKP verification costs.
  2. Switching to Groth16 once we don't need to iterate as fast. Noir good for fast iterations, Circom is good for costs (but a pain to write).
  3. ZAKA - Account abstraction with ZKP
  4. Smooth UX with transaction statuses.

Built With

  • cairo
  • mist
  • next
  • noir
  • vercel
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