White paper
Why PCASH exists and how it works, in one document.
Learn
PCASH in six ideas
Private money Ethereum can program, in short. The white paper makes the full case, and the protocol specification has the exact rules.
Private payments, in PCASH or your own asset
When you pay, the sender, the recipient, the amount and the asset stay private, and so does every balance. Each payment carries a zero-knowledge proof: the network checks that it is valid without learning any of those details.
There is no public PCASH, nothing to deposit and nothing to withdraw, and a PCASH account holding nothing looks the same as one holding a lot. Anyone can create another asset, such as a private dollar or a token, and it moves with the same privacy.
What can other people see?
That an account registered, that a transaction happened, its fee and timing, and which of the two transaction sizes it used. If you publish a transaction from your own Ethereum address, that address is linked to it. They cannot see the sender, recipient, amount or balance.
White paper: What is publicIs PCASH ETH, or wrapped ETH?
No. PCASH is its own asset. It exists only inside PCASH, and no bridge redeems it for ETH. You do pay Ethereum gas, in ETH, to publish transactions.
You choose the rules for your money
Every PCASH account sets its own spending rules: a signature, a passkey, two of three keys, a recovery key held by a friend, or any rule anyone writes, with no one's permission. The rule that approved a payment stays private.
PCASH contracts are accounts whose rules can never change, which makes escrow, vesting and shared treasuries trustworthy.
What happens if I lose my Ethereum key?
Your Ethereum key is needed once, to create your account. After that, your account's own rules decide who can spend, and they can use other keys. What never changes is the secret your account needs to spend its notes, fixed when the account is created. No one can restore it, and losing it loses the PCASH. The wallet on this site derives that secret from your Ethereum key, so there is nothing extra to back up, and losing the key loses your PCASH.
White paper: What if a key is lost or stolen?
Ethereum apps can move private money
Rules can act on what happens on Ethereum, and Ethereum contracts can move PCASH. The Marketplace on this site works this way: a seller locks PCASH in a PCASH escrow contract, and the buyer's single Ethereum transaction pays the seller in ETH and claims the PCASH. If no one buys before the deadline, the seller takes the PCASH back. No operator holds either side's funds.
Can I turn PCASH back into ETH?
Only by selling it to someone for ETH, through a PCASH escrow contract. There is no withdrawal and no bridge.
Payments can carry the proofs recipients need
A recipient can ask a payment to prove what it needs, such as that its funds came only from approved sources. The sender proves it without revealing who paid, and the proof travels on with the money, so the next recipient can check it too. A stablecoin issuer can require the same proof before it redeems. What you can build.
White paper: Proofs that travel with money
Ethereum orders the transactions
PCASH transactions are published to Ethereum, and every PCASH node derives the same state from Ethereum's history. There is no validator set, sequencer, operator or upgrade key, and anyone can post transactions. The rules change only if people choose to run new software, the way Ethereum itself changes.
Why isn't PCASH a smart contract?
A privacy contract has to choose. An immutable one cannot fix a bug without moving everyone to a new contract, which breaks their privacy. An upgradeable one is only as safe as whoever controls upgrades. PCASH is defined by rules for reading Ethereum history instead, so each version is immutable, and a new version applies only if people choose to run it.
White paper: No one can censor or change itWhat am I trusting?
Ethereum's consensus and history, the soundness of the zero-knowledge proof system, and the correctness of PCASH's circuits and software. When you buy PCASH with ETH, you also rely on an honest node to check the listing, which can be your own. Not a sequencer, an administrator, a bridge, or other users keeping their money in a pool. The latest security review and its report are on the Security page.
White paper: What you trust
Earn PCASH by supplying activity
New PCASH is issued for successful transactions, including mining: publishing a transaction with no payment to make. You pay Ethereum gas, not PCASH, and each mine adds cover for other people's payments. Total issuance is capped at one billion PCASH, with no premine, allocation or sale.
Each block's issuance is limited and shared equally among the transactions that earn it. The amount per transaction declines as supply is issued and adjusts to how quickly issuance is running.
How do I get PCASH?
Mine it on the Get PCASH page, earn issuance and fees by relaying transactions, or buy it from a holder for ETH in the Marketplace. Mining and receiving PCASH need no account. Spending does, and creating one takes one Ethereum transaction.
Read further
Security
How PCASH protects its money and the people who use it, and the latest security review.
Protocol specification
The exact rules every implementation follows.
Ask an AI
The white paper, the Security page and the specification in one paste, so a model has the rules, the reasons for them and how PCASH is protected. Try asking: “How does this protocol work, and is it a good design?”
Building on PCASH or running a node? Start at Developers.