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Privacy Architecture

Imagine you have money in your wallet. Normally, when you use it on a blockchain, everyone can see how much you have, who you pay, and how much you send. Orbinum changes this using zero-knowledge cryptography, allowing you to make transactions where these details remain private.

This guide shows you how that privacy system works, what operations you can perform, and what guarantees you get.

What can you do in Orbinum?​

Shield (Protect)

Deposit public tokens into the private pool. Your funds become confidential.

Transfer (Send)

Send private tokens to other users without revealing amounts or identities.

Unshield (Reveal)

Withdraw tokens from the private pool to a public account visible on the blockchain.

Selective Disclosure

Prove properties of your funds without revealing exact amounts (Q2 2026).

How it works: The Shielded Pool​

The shielded pool is like a common vault where all private funds are mixed together. When you deposit tokens, they become notes — cryptographic receipts that only you can spend.

What is a "note"?

A note is like a private bill that contains:

  • Amount: how many tokens it represents
  • Asset ID: what type of token it is (ORB, USDT, etc.)
  • Owner: who can spend it (your public key)
  • Blinding: a random number to hide all of the above

Operation 1: Shield (Deposit to Private Pool)​

When you shield, you convert public tokens into private ones by depositing them into the shielded pool.

Flujo paso a paso​

1
Create a note off-chain

Your wallet generates a note with your amount, asset ID, public key, and a random blinding factor

2
Calculate the commitment

commitment = Poseidon(amount, asset_id, owner_pubkey, blinding)

3
Send the shield transaction

The runtime locks your public tokens and adds the commitment to the Merkle tree

4
Store your note locally

Your wallet stores the complete note to be able to spend it later. ⚠️ If you lose it, you lose the funds.

What is still public?​

Visible
  • Your public account deposited funds
  • The deposit timestamp
  • Commitment (meaningless hash)
Hidden
  • Exact amount deposited
  • Asset ID (partially)
  • Blinding factor
  • Where those funds will go next

Operation 2: Private Transfer​

A private transfer moves funds within the shielded pool without revealing who sends, who receives, or how much is sent.

Step-by-step flow​

1
Select input notes

Your wallet searches for notes you own with enough balance to cover the amount to send

2
Create output notes

One note for the recipient (e.g., 50 USDT) and one for you with the change (e.g., 50 USDT remaining)

3
Generate ZK proofs off-chain

This takes 2-5 seconds. The proof validates that:

  • You own the input notes
  • The notes are in the Merkle tree
  • Amounts balance (input = output)
  • Nullifiers are correct
4
Send the transaction with the proof

The runtime verifies the ZK proof (~3ms), marks nullifiers as spent, and adds the new commitments

What remains public?​

Visible
  • A private transaction occurred
  • Nullifiers (meaningless hashes)
  • New commitments (meaningless hashes)
  • Transaction timestamp
Hidden
  • Who sent
  • Who received
  • How much was sent
  • Which asset was used
  • Relationship between inputs and outputs
What is a "nullifier"?

A nullifier is a unique hash calculated from a note when you spend it. It's published on-chain to prevent that same note from being spent twice (double-spending). Without your private key, no one can link the nullifier to the original commitment, maintaining your privacy.

Operation 3: Unshield (Withdrawal from Private Pool)​

Unshield takes tokens out of the private pool and sends them to a public account. This operation reveals the amount and the recipient.

Step-by-step flow​

1
Select a private note

Choose a note with sufficient balance for the withdrawal

2
Generate ZK ownership proof

The proof demonstrates you own the note and that the amount is correct, without revealing other details

3
Send unshield transaction

Includes: ZK proof, nullifier, amount to withdraw, and recipient's public address

4
Funds are transferred publicly

The runtime verifies the proof, marks the nullifier as spent, and transfers tokens to the public account

What remains public?​

Visible
  • Exact amount withdrawn
  • Public recipient
  • Asset ID
  • Timestamp
Hidden
  • Who withdrew the funds
  • Where the funds came from
  • How much balance remained in the note
  • Previous history of those funds
Consider this before unshielding

Unshield links your private identity with a public account. If someone observes that you deposited 100 USDT and then withdraw 100 USDT shortly after, they can infer those funds are probably yours. For maximum privacy, wait and mix with other users before withdrawing.

Operation 4: Selective Disclosure​

Available in Q2 2026

Selective disclosure allows you to prove properties of your funds without revealing exact amounts. It's useful for regulatory compliance and enterprise use cases.

Range Proofs

Prove that your balance is within a range without revealing the exact amount. Example: "I have more than $10,000"

Compliance Proofs

Demonstrate compliance with regulations without exposing your complete financial history

Audit Trails

Provide selective audit trails to authorities without compromising general privacy

The Merkle Tree: Where Commitments Live​

All commitments are stored in a binary Merkle tree of depth 20, allowing up to 1,048,576 notes.

Why a Merkle tree?

The Merkle tree allows proving that a note exists in the pool without revealing which one it is. When you spend a note, you generate a "Merkle proof" that demonstrates its inclusion in the tree without pointing to exactly where it is. This breaks the link between deposits and spends, maintaining your privacy.

Privacy Guarantees and Limitations​

✅ What is protected​

  • Amounts in private transfers (fully hidden)
  • Identities of sender and recipient in transfers
  • Relationship between inputs and outputs (unlinkable)
  • History of a note before being spent
  • Individual balances within the pool

⚠️ What remains visible​

  • Shield/unshield operations link public accounts with the pool
  • Transaction timing (when they occur in each block)
  • Merkle tree growth (size of the anonymity set)
  • Asset type can be partially inferred in some cases
  • Unshield amounts are completely public
Best practices for privacy
  • Use common denominations: instead of 137.42 USDT, round to 100 or 150
  • Wait before unshielding: don't withdraw immediately after depositing
  • Mix with other users: the more transactions there are, the larger your anonymity set
  • Split funds into multiple notes: don't use a single large note

Multi-Asset: One Pool for All Tokens​

Orbinum's shielded pool supports multiple assets (ORB, USDT, DAI, etc.) in the same Merkle tree.

Advantages of the multi-asset approach​

Unified anonymity set

All notes from all assets contribute to the same anonymity set, increasing everyone's privacy

Efficient verification

A single Merkle tree simplifies proof verification compared to separate trees per asset

Future atomic swaps

The design facilitates private cross-asset exchanges in future versions

Learn More​