Using Private Transfers

Why Private Transfers?

UPD is a standard ERC-20. Plain transfers — like any other token — are fully visible on-chain: sender, recipient, and amount are public to anyone.

To transact privately, you shield UPD into the Universal Private Pool. Inside the pool, transfers use zero-knowledge proofs: the network verifies that balances are conserved and funds are compliant, without learning who sent what to whom.

Mint UPD           → visible on-chain (amount public)
Shield into UPP    → visible on-chain (amount enters pool)
Transfer in pool   → private (ZK proof — sender, recipient, amount hidden)
Unshield from UPP  → visible on-chain (amount leaves pool, recipient public)

The Three Steps

1. Shield

Move UPD from your public wallet into the private pool. This creates an encrypted note — your private balance record.

• What's visible: your address transferred X UPD to the pool contract
• What's hidden: nothing yet — shielding is a public deposit
• What you receive: an encrypted note recording your claim to X UPD inside the pool

2. Transfer (Private Send)

Send UPD to another user inside the pool. You prove ownership of your note without revealing which note it is.

• What's visible: a ZK proof was verified on-chain — no sender, no recipient, no amount
• What the recipient gets: an encrypted note for the amount you sent
• What you get: an encrypted change note for your remaining balance

Recipients share a stealth address (0zk1...) to receive funds. Each payment goes to a fresh one-time address derived from that — so even their public address never appears on-chain.

3. Unshield (Withdraw)

Move UPD from the pool back to a public address. This requires a compliance proof from an ASP (Association Set Provider) confirming your funds originate from a compliant address.

• What's visible: X UPD transferred from the pool to the recipient address
• What's hidden: which note you spent, your prior transaction history in the pool
• Ragequit: if all ASPs refuse you, you can always withdraw to your original deposit address — no one can trap your funds

Viewing Keys

Every note you hold has a viewing key. Share a viewing key with an auditor or tax authority to prove a specific transaction without exposing your entire history.

You hold: 100 notes across 3 months of activity
Auditor asks: prove you received payment on March 12
You share: viewing key for that one note only
Auditor sees: amount, timestamp, proof of receipt — nothing else

Compliance

UPP isn't about evading regulators. It's about controlling who sees what, and when.

The ASP layer verifies that funds originate from compliant sources. Withdrawals require a ZK proof of compliant origin — the verifier learns "this address is in the approved set" without learning which address. See ASP Compliance for details.