What stays hidden

Opacra uses Monero's privacy layer without changing it. It runs on every payment. There's nothing to switch on.

A real payment from the testnet

Block 31,681. These are the fields every node stores. See it on the explorer.

Sender
Each of the 2 inputs points at 16 older outputs. One is real and nothing says which.
Receiver
There's no address anywhere in the transaction.
Amount
Only the two sides of the payment know it.
One-time keys
15c71ada1be92eb129bc15bf5bb23aff804c5e18686f387ecc25045f771ca26715c71ada1be92e…771ca267
762eb143d5d55a951a0817ffd15167ec8e5e757cdb95351a113c52c13b991f29762eb143d5d55a…3b991f29Used once. They don't link to any address.
Encrypted amounts
51d4ee248de16062
dfa7f0fc2602a722The receiver's view key opens these.
Key images
8ec0571c57f445d379371c5145f2970eccf8b64bcf394a29afdaa894528dad298ec0571c57f445…528dad29
70ed028683da6a44f72238e369d6678bd8f4282e28d5aa972df1681255cf679b70ed028683da6a…55cf679bThese stop double spends without showing what was spent.
Fee
0.0028509 OPCAPublic, same as Monero.

16 outputs per input. One is the real spend. To the network they look identical.

Ring signatures hide the sender

Each input is signed as one of 16 older outputs. The signature proves one of them is being spent without showing which. The ring size is fixed at 16, so every payment looks the same.

Stealth addresses hide the receiver

The sender works out a fresh one-time key for every payment. Your address never goes on the chain, and two payments to you can't be linked.

RingCT hides the amount

Amounts are encrypted. Bulletproofs+ let every node confirm no coins were created from nothing without seeing a number.

Dandelion++ hides where it started

A new payment passes through a few nodes quietly before it spreads, so most nodes can't tell where it came from.

What you can choose to show

ToolWhat it showsWhen you'd use it
Payment proofOne payment reached one address, tied to a message like an invoice numberA dispute with a shop
Reserve proofA balance exists, without the history behind itShowing you're solvent
View-only walletIncoming payments, with no power to spendYour accountant

All three passed in the 31 October test report.

Good to know

Fees and block times are public, and the nodes you connect to can see your IP address, as with any network software. Optional Tor is planned after mainnet. Privacy gets stronger as more people use the chain, and running a public node helps everyone.