Every privacy coin is really just a different answer to one question: how do you move money on a public ledger without showing the whole world who paid whom, and how much? This guide explains the main techniques in plain words, then puts them side by side so you can see what each one actually hides.
No math degree needed. If you can picture an envelope, a crowd, and a sealed box, you can understand all of this.
The problem privacy tech solves
A normal blockchain like Bitcoin is a public spreadsheet. Every transaction shows three things forever: the sender address, the receiver address, and the amount. Anyone can read it, and firms exist whose entire job is linking those addresses to real names.
Privacy technology hides one or more of those three things. The best systems hide all three by default. Here is how, technique by technique.
Ring signatures: hiding the sender
Picture signing a document, but instead of your signature alone, it is signed by you plus a crowd of other plausible signers, and nobody can tell which one was really you. That is a ring signature.
When you spend a coin, the system mixes your real input with a set of decoy inputs pulled from the blockchain. An outside observer sees the group and knows the spend came from someone in it, but cannot tell who. This is how Monero hides the sender on every transaction.
Stealth addresses: hiding the receiver
You publish one address, but every payment you receive actually lands at a fresh, one-time address that only you can detect and spend. So even though people send to "you," the public ledger never shows a reused receiving address to cluster.
This is what hides the receiver. Monero uses stealth addresses on every transaction, which is why you can paste the same address everywhere without it linking your payments together.
Confidential transactions and RingCT: hiding the amount
Here is the clever one. Using a cryptographic trick called a commitment, the network can verify that the inputs of a transaction equal the outputs, so no coins were created from thin air, without anyone seeing the actual numbers. The amount is sealed in a box the math can check but eyes cannot read.
Monero combines this with ring signatures into a system called RingCT (Ring Confidential Transactions), so sender, receiver, and amount are all hidden at once, by default, on every single transaction.
zk-SNARKs: proving without revealing
A zero-knowledge proof lets you prove a statement is true without revealing the information behind it. A zk-SNARK is a compact, fast version of that. Applied to money, you can prove "this transaction is valid and balanced" while revealing nothing about sender, receiver, or amount.
This is the engine behind Zcash's shielded transactions. The catch with Zcash is that privacy is optional. Coins can sit in a transparent pool or a shielded pool, and privacy only holds while funds stay shielded. Default-on versus opt-in is the core difference between Monero and Zcash, which we dig into in Monero vs Zcash.
FCMP++: the next step for Monero
Monero's ring signatures have used a limited decoy set, which is strong but not infinite. FCMP++ (full-chain membership proofs) is an upgrade designed to let the decoy set be the entire chain rather than a small ring, which sharply increases the anonymity set. Treat the exact rollout timing as a moving target, but the direction is clear: bigger crowds, stronger sender privacy.
Mixers and CoinJoin: privacy bolted onto transparent coins
Bitcoin has no built-in privacy, so people add it after the fact. A CoinJoin combines many users' payments into one big transaction so individual inputs and outputs are hard to link. Mixers do something similar as a service. These help, but they are opt-in, they leave their own on-chain fingerprint, and some have drawn heavy regulatory heat. They are a patch, not a foundation. A coin private by design beats a transparent coin wearing a disguise.
All of it in one table
| Technique | What it hides | On by default? | Used by |
|---|---|---|---|
| Ring signatures | Sender | Yes | Monero |
| Stealth addresses | Receiver | Yes | Monero |
| RingCT / confidential tx | Amount (with sender) | Yes | Monero |
| zk-SNARKs | Sender, receiver, amount | Optional (shielded pool) | Zcash |
| FCMP++ | Sender (bigger anonymity set) | Upcoming | Monero |
| CoinJoin / mixers | Links between inputs/outputs | Opt-in add-on | Bitcoin, others |
| View keys | Lets you selectively reveal | You choose | Monero, Zcash |
One bonus entry worth knowing: a view key lets you hand someone read-only visibility into your own transactions, say for an accountant or an audit, without giving up spending control. Privacy by default does not mean you can never prove anything. It means you decide who sees what.
So which is "most private"?
If privacy is on by default for every transaction, you cannot accidentally leak by forgetting to switch it on. That is Monero's design and it is why, in practice, it is the benchmark for default privacy. Zcash's zk-SNARKs are arguably stronger cryptography, but optional privacy means most real-world usage and liquidity is less protective than it could be. The best tech in the world does nothing if it is a setting people forget to flip.
Frequently asked questions
What is the difference between Monero and Zcash privacy? Monero hides sender, receiver, and amount on every transaction by default using ring signatures, stealth addresses, and RingCT. Zcash can hide all three with zk-SNARKs, but only when funds are in its shielded pool, and that is optional.
Are mixers the same as a privacy coin? No. A mixer bolts weak, opt-in privacy onto a transparent coin like Bitcoin and leaves its own footprint. A privacy coin builds privacy into the protocol itself.
Does a no-KYC swap make me private on Bitcoin? It keeps your identity off the exchange, which is real and useful, but Bitcoin's ledger is still public. For on-chain privacy of the amounts and addresses themselves, you need a privacy coin like Monero.
What is a view key? A read-only key that lets you reveal your own transaction history to a chosen party, like an auditor, without giving up control of your funds. It makes selective transparency possible on top of default privacy.
Is zk-SNARK technology better than ring signatures? Cryptographically, zero-knowledge proofs are very strong. But Monero's default-on approach often gives better real-world privacy than Zcash's optional shielding, because users cannot forget to turn it on.