Privacy, security, and limitations - Starknet Documentation

Privacy (informal)

What observers see (or don’t) in practice:

Topic	What leaks / what’s protected
Sender	External observers see paymaster as sender; paymaster may see IP.
Receiver	Hidden except when a new channel is opened (recipient address on-chain once per sender–recipient pair).
Amounts	Encrypted in normal notes; deposits, withdrawals, and open notes expose amounts (and tokens) as designed.
Auditor	Can decrypt registered users’ viewing keys when authorized; cannot sign spends.

Fund security

Double-spend — nullifiers are unique and recorded; proof ties nullifier to existing note.
Unauthorized spend — requires valid account signature in proof; auditor has viewing key only, not signing authority.

Limitations

New channel + deposit/withdraw in same tx or tight timing — can link recipient to public address activity; wallets should separate these flows when possible.
Deposit/withdraw heuristics — distinctive amounts or immediate in/out weaken privacy (common to all pools).
Reverted txs — if a note slot was touched then reverted, reusing the same note id can link txs; mitigations include burning dummy writes to exposed ids (paper §11.3.3).

For the full analysis see IACR 2026/474 §11.

Anonymous DeFi and open notes

Paymasters and transaction submission