STRKVeil
Private DEX Swaps
Created on 1st December 2025
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STRKVeil
Private DEX Swaps
The problem STRKVeil solves
The Core Problem: MEV Attacks
When trading on DEXs, every transaction is visible in the mempool before execution. MEV bots exploit this by:
- Front-running: Executing their trades before yours
- Sandwich attacks: Placing trades before AND after yours
Result: Users lose 0.1-5%+ of trade value, get worse prices, and experience failed transactions.
What Our Solution Enables
1. Private Trading
Large traders can execute significant trades without revealing intentions. Trade details are hidden until execution, preventing MEV bots from front-running.
Example: Whale swapping 10,000 ETH → USDC gets fair execution without price manipulation.
2. Fair Price Execution
Regular users get market prices without bot interference. No price manipulation means better execution and more tokens received.
Example: Swapping 1 ETH expecting 3,000 USDC - you get closer to 3,000 instead of 2,950 after MEV extraction.
3. Protection for High-Value Trades
Large trades execute safely without being prime targets for MEV extraction. Reduced risk of failed transactions and better execution confidence.
Example: DeFi protocol rebalancing 50,000 ETH → USDC without MEV losses.
4. Arbitrage Protection
Arbitrage opportunities remain hidden. Bots can't copy your strategy, allowing you to capture opportunities without competition.
Example: Spotting price difference between DEXs - your trade stays private, you capture the opportunity.
5. Strategic Trading
Complex trading strategies remain hidden. Bots can't reverse-engineer your approach, enabling better execution of multi-step plans.
How It Makes Tasks Easier
For Regular Users
- Before: Worry about MEV bots, accept worse prices, unexpected slippage
- After: Trade with confidence, better prices, predictable outcomes
For DeFi Protocols
- Before: Large trades expensive due to MEV, need to split trades, complex workarounds
- After: Execute large trades efficiently, simpler logic, lower costs
For Traders
- Before: Arbitrage gets front-run, strategies copied, need expensive private mempools
- After: Arbitrage stays private, strategies hidden, more flexibility
Safety Improvements
- Transaction Security: No front-running, sandwich attacks, or back-running
- Financial Safety: Better prices, reduced slippage, lower costs, predictable outcomes
- Privacy Safety: Trade anonymity, strategy protection, position hiding
Real-World Use Cases
- Institutional Trading: Execute large trades without revealing positions
- DeFi Protocol Operations: Rebalance portfolios without MEV extraction
- Arbitrage Trading: Capture opportunities without bot competition
- Personal Trading: Trade with confidence and fair prices
- High-Frequency Trading: Execute many trades without front-running
Challenges we ran into
Development Challenges
Challenge 1: Understanding ZK Proofs vs Encryption
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The Problem: We initially thought ZK proofs could "encrypt" trade parameters and the contract could "decrypt" them.
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What Failed: Attempted XOR encryption with public keys, stored decryption keys in contract storage.
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The Solution: Learned that ZK proofs prove knowledge without revealing it. They don't hide data that needs to be acted upon. Moved to off-chain storage for trade parameters, using ZK proofs only for authorization.
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Key Learning: ZK proofs are for proving knowledge, not for hiding data that needs to be used.
Challenge 2: The Mempool Visibility Problem
- The Problem: Even with ZK proofs, if trade parameters were included anywhere in the transaction, MEV bots could see them.
What Failed:
- Public outputs in circuit (visible in proof)
- Private inputs only (contract couldn't execute)
- Calldata parameters (always public)
The Solution: Implemented off-chain oracle pattern - store params off-chain, submit only
intent_id
, contract fetches during execution.Key Learning: The timing of when data becomes known is crucial. Off-chain storage solves the timing problem.
Challenge 3: Circom Syntax Errors
The Problem: Multiple syntax errors prevented compilation -
signal private input
(invalid),!==
operator (not supported), missing includes.The Solution: Changed to
signal input
(private by default), usedLessThan
component, added proper Circomlib includes.Key Learning: Circom has specific syntax rules. Inputs are private by default unless declared public.
Challenge 4: MEV Bot Copying Prevention
The Problem: What prevents MEV bots from copying the exact transaction and submitting it themselves?
The Solution: Implemented caller verification - signed data includes user address, contract checks
caller == user
, MEV bot's address doesn't match, transaction fails.Key Learning: Always bind transactions to specific users. Signature verification + caller check prevents copying attacks.
Technologies used
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