Why “pseudonymous” is not “anonymous”
A public blockchain records every transaction forever. Bitcoin and Ethereum addresses are pseudonyms — stable identifiers not directly tied to a name, but trivially linkable to one once a KYC'd exchange, a merchant, or a public donation reveals the mapping. The Tracing unit covers how chain analysis exploits this: common-input-ownership, peeling chains, and cluster expansion turn pseudonyms into actor clusters, and the off-ramp ties the cluster to a person.
“Private” crypto spans: none (Bitcoin/Ethereum base layer), optional (Zcash shielded, CoinJoin), and default (Monero). More privacy usually means weaker auditability, higher transaction size/cost, and more regulatory friction.
Privacy coins: privacy baked into the network
Monero (XMR)
is the leading privacy-by-default coin. Every transaction hides the sender (via ring signatures — the real signer is hidden among decoys), the recipient (via stealth addresses — a unique one-time address per transaction), and the amount (via RingCT, a confidential-transactions scheme). Privacy is the default, not optional, which is why Monero is the hardest major coin to trace and the most frequently delisted by regulated exchanges.
Zcash (ZEC)
uses for optional shielded transactions: the sender, recipient, and amount are cryptographically hidden while still proving the transaction is valid. Crucially, Zcash privacy is opt-in — most Zcash transactions are transparent, which is one reason Zcash has faced less exchange delisting than Monero. Shielded pools that mix transparent and shielded funds can still leak metadata at the deshielding boundary.
What each transaction hides
Others worth knowing
- Dash — “PrivateSend” is a CoinJoin-like mixer built in; like Zcash, privacy is optional, and most txs are transparent.
- Secret Network — encrypted smart contracts (privacy at the compute layer, not just the payment layer).
- Aztec / ZK L2s — bringing shielded computation to Ethereum via zero-knowledge rollups (still emerging).