Private is not invisible.

01What Hushfund does and does not hide

Hushfund reduces on-chain linkability between a deposit and a later withdrawal by proving membership in a Merkle tree instead of naming a specific deposit. It does not make you anonymous.

02What is public on-chain

• Deposits are public transactions. The funding wallet, the vault (and therefore the amount: 10, 50, 100 or 1000 USDC) and the time are visible.
• Withdrawals are public. The recipient address, the vault, the time and the payout are visible.
• Loans and repayments are public, including recipients and amounts. A repayment inserts a new note to reduce linkability, but it does not erase history.

03Anonymity set and correlation

Privacy depends on how many other notes share your denomination and yield bucket. A small set means fewer plausible sources for a withdrawal.

• Withdrawing soon after depositing makes timing correlation easy.
• Withdrawing to an address linked to you, or to the same address that deposited, can make the link obvious.
• Unusual patterns, such as distinctive amounts across several notes or regular schedules, can be matched.
• Borrowing and repaying around the same time as other public activity can connect the loan to a later withdrawal.

04RPC, relayer and network metadata

The API server, the relayer, your RPC provider and the sign-in provider can see network metadata such as IP addresses and request timing. The relayer submits sponsored transactions and sees the action details it is asked to relay. Zero-knowledge proofs do not hide this layer.

05Sign-in, embedded and external wallets

You can use an embedded wallet or a supported external wallet. An external wallet connection is not always the same as an authenticated sign-in. The selected wallet holds USDC and signs authorizations for deposits and repayments; withdrawals and loans pay out to the recipient you enter.

Your sign-in and your notes are separate. The sign-in account does not own a deposit and does not give access to a note. Anyone holding a note can withdraw it from any wallet. The wallet you sign in with is linked to the deposits and repayments it funds.

06Local notes, backups and lost secrets

Notes are generated in your browser and never sent to a server. By default they live only in memory for the current tab. You can opt in to keeping them in local storage; then anyone with access to the browser profile, an extension with page access, or malware could read them. Clearing site data deletes them.

The optional hushfund-recovery.json backup is encrypted in your browser with AES-256-GCM using a key derived from your recovery password (PBKDF2-SHA-256, 250,000 iterations, minimum 12 characters). The password is never stored or sent.