Privacy Cash

Privacy Cash is a non-custodial privacy protocol built on Solana that lets users transfer, swap, and bridge tokens without creating an on-chain link between their sending and receiving wallet addresses. The protocol launched in mid-2025 and is backed by AllianceDAO, with its on-chain program, zero-knowledge circuits, and developer SDK fully open-sourced and formally verified.

How It Works

Privacy Cash relies on three interlocking components: zero-knowledge proofs, an append-only Merkle tree, and a relayer network.

When a user wants to make a private transfer, they deposit tokens into a protocol-managed anonymity pool. That deposit is recorded as an encrypted commitment on a Merkle tree that lives on-chain. The user receives a cryptographic note—essentially a secret that proves ownership of the deposit. At withdrawal time, the user's browser generates a Groth16 zero-knowledge proof client-side, demonstrating knowledge of a valid note without revealing which specific deposit it corresponds to. The signed transaction is then broadcast through a relayer, which submits it to the network and pays the gas fee, further decoupling the user's original wallet from the on-chain activity.

Because proof generation happens client-side, relayers never see the recipient address or the amount before it is cryptographically committed. On Solana, the on-chain program is written in Rust using the Anchor framework (v0.31.1), with circuits compiled via Circom v2.2.2. The upgrade authority for the deployed program is held by a multisig.

Compliance Architecture

Privacy Cash is designed to be OFAC-compliant. Before processing a withdrawal, each relayer screens the depositor's wallet address through CipherOwl, a blockchain compliance data provider. Flagged addresses associated with sanctions lists are rejected at the relayer level before they can complete a withdrawal. This positions Privacy Cash differently from fully permissionless mixers: it maintains a compliance gate at the infrastructure layer while keeping the cryptographic privacy guarantees intact for non-flagged users.

The project documentation also cautions users about best practices to avoid amount-based chain analysis. If identical amounts are deposited and withdrawn within a short window, statistical correlation remains possible even with ZK proofs—users are advised to withdraw to fresh non-custodial wallets.

Supported Assets and Services

On Solana, Privacy Cash supports SOL natively, with USDC, USDT, and additional SPL tokens also available in the protocol's pools. Three types of privacy-preserving operations are offered:

Private Transfers allow users to send tokens to any recipient address with no on-chain connection between sender and receiver. This feature is available across Solana, Base, and Ethereum.

Private Swaps are available exclusively on Solana. When a user wants to exchange one token for another privately, Privacy Cash routes the swap through Jupiter, Solana's leading DEX aggregator, within the shielded environment. This means both the swap itself and the resulting token transfer preserve privacy.

Private Bridging enables cross-chain movements via a NEAR Intents market maker. A user can move assets between Solana and other supported chains without the originating and destination wallets being linked on either chain.

Fee Structure

Deposits are always free. On Solana, withdrawals carry a flat fee of 0.006 SOL plus a 0.35% protocol fee on the amount withdrawn. Private swaps cost 0.008 SOL plus 0.35% plus Jupiter's standard swap fees. Private bridging costs 0.006 SOL plus 0.35% on the Solana side, plus an additional 0.1% charged by the NEAR Intents market maker. On Base and Ethereum, the flat SOL fees are replaced with equivalent network token fees (0.00025 ETH on Base), while the percentage fees remain the same.

Security and Audits

Privacy Cash places heavy emphasis on verifiable security. As of mid-2026 the protocol has completed 20 audits in total—14 covering the Solana program and 6 covering the Base and EVM implementations. Named auditors from the GitHub repository include Accretion, HashCloak, Zigtur, and Kriko. Beyond these traditional audits, the Solana on-chain program has been formally verified by Veridise, a cryptographic security firm that specializes in ZK circuit and smart contract verification. The deployed program binary is anchored to a publicly posted on-chain hash, allowing anyone to verify that the running code matches the audited source.

Developer SDK and Integrations

Privacy Cash publishes a TypeScript SDK (available via the Privacy-Cash/privacy-cash-sdk repository) that allows other projects to integrate shielded pool functionality directly. The core protocol repository is composed primarily of TypeScript (81.6%) and Rust (16.1%), with Circom circuit files making up a small portion. The Rust crate is also published to crates.io as privacy-cash.

The integration model has already attracted at least one notable partner: ORE, a Solana-based mineable token, launched an "Official Shielded Pool" through Privacy Cash, making private ORE transfers available on Solana mainnet shortly after Privacy Cash's launch.

Traction

Privacy Cash reported $450 million in total privately transferred and swapped volume as of mid-2025 through its marketing materials. The protocol is available through the web application at privacycash.org, where users connect a Solana wallet to access the transfer, swap, and bridge interfaces. Tutorial resources are linked from the main site, and a Dune Analytics dashboard provides public on-chain metrics.

Positioning

Privacy Cash enters a small field of Solana privacy protocols. It distinguishes itself from earlier efforts on the network by combining multi-asset support (SOL and SPL tokens) with integrated swap functionality via Jupiter and cross-chain bridging via NEAR Intents—all within a single shielded interface. Its compliance-first design, using relayer-level CipherOwl screening, is an attempt to make on-chain privacy accessible to users and institutions operating under regulatory constraints, rather than positioning itself as a tool for bypassing oversight.