fhevm-privacy-constraints
FHE Privacy Constraints
Use this skill when a feature depends on knowing balances, proving holdings, calculating rewards, or enforcing product rules over confidential token state.
When To Use
- Designing rewards or incentives for confidential tokens
- Planning analytics, indexing, or Goldsky-derived metrics
- Reviewing whether a contract can read or enforce balance-based rules
- Evaluating sybil resistance claims for privacy-preserving mechanisms
- Choosing between free-transfer privacy and accountable locked balances
Start With Visibility, Not Assumptions
For each feature, first classify the relevant data:
- public onchain
- hidden but user-readable
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Use when you need overflow-safe encrypted arithmetic on euint64 values. Covers the OpenZeppelin FHESafeMath library (tryIncrease, tryDecrease, tryAdd, trySub), uninitialized-handle semantics, and when to prefer it over raw FHE.add / FHE.sub.
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Use when implementing two-step public decryption for state-changing operations in FHEVM. Covers makePubliclyDecryptable, off-chain proof retrieval, onchain verification with checkSignatures, and the critical single-step unwrap bug.
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