Title: Fairblock · Vendor · EthSystems

URL Source: https://original.es-internal.pages.dev/vendors/fairblock/

Markdown Content:
---
description: Fairblock provides confidential balances and transfers for assets (e.g., stablecoins) that remain issued and liquid on an originating chain (e.g., EVM networks), while confidentiality logic executes on FairyRing, a purpose-built confidentiality execution layer.
title: Fairblock · Vendor · EthSystems
image: https://original.es-internal.pages.dev/og.png
---

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# Fairblock: Cross-chain Confidential Transfers (lightweight homomorphic ops + ZK)

## Fits with patterns

* [Selective disclosure (viewing keys + ZK proofs)](/patterns/pattern-regulatory-disclosure-keys-proofs/): scoped disclosure for audit and compliance workflows

## Not a substitute for

* Anonymity, mixers, or large anonymity sets: Fairblock focuses on amount and balance confidentiality, not obfuscasting participant identities by default.
* Stealth addresses (unlinkable recipients): requires separate stealth address infrastructure if counterparty unlinkability is required.
* Full transaction graph privacy: relationship metadata may still be inferable depending on integration design.

## Architecture

High-level components:

1. Origin chain (e.g., EVM): Minimal locking smart contract
  * Locks/unlocks the underlying ERC-20 tokens
  * User-facing interface for deposit/transfer/withdraw flows
2. FairyRing: confidentiality execution layer
  * CosmWasm contracts maintain an encrypted chain
  * Verifies ZK proofs for valid encrypted state transitions
  * Performs lightweight homomorphic add/subtract for balance updates
3. Cross-chain messaging (IBC-style)
  * Relays packets between the origin chain and FairyRing
  * Relayers transport packets but are not intended to be trusted for correctness

## Privacy domains

Encrypted (intended):

* Amounts and balances (encrypted state)

Public (intended):

* Sender and receiver addresses (confidentiality, not anonymity)
* Existence and timing of origin-chain transactions that invoke the locking contract

## Selective disclosure (compliance posture)

FairyRing supports selective disclosure for audits and investigations via scoped decryption access using threshold identity-based encryption (IBE), aiming to avoid a single persistent global audit key

## Enterprise demand and use cases

* Treasury operations: encrypt balances and flows while keeping counterparties known and auditable
* Payroll and vendor payouts: amount confidentiality with the ability to disclose specific transactions when required
* B2B payment rails: confidentiality layer for regulated payment operations that still require reporting and audit

## Technical details

* Cross-chain design connecting an origin chain locking contract with FairyRing as confidentiality layer
* Encrypted layer and ZK proof verification for valid state transitions
* Lightweight homomorphic operations for balance updates
* Threshold IBE for scoped selective disclosure

## Strengths

* Preserves existing asset issuance and liquidity on EVM chains (no token contract changes required)
* Clear compliance posture via scoped selective disclosure (IBE-based); avoids a single persistent audit key
* Security: avoids off-chain coprocessing, single-TEE trust models, MPC honest-majority assumptions, and external prover service dependencies (proof generation is local)
* Performance/UX: no bridging of funds and no new wallet behavior; lightweight cryptography targets low latency flows (vs. long proof delays common in many privacy systems)

## Risks and open questions

* Relationship privacy is optional: the default model prioritizes confidentiality (amounts/balances) with traceable addresses; deployments that need relationship obfuscation/anonymity can layer additional primitives, but that typically increases complexity/latency and may introduce stricter compliance requirements that not all partners want
* Cross-chain messaging (liveness, not custody): messaging mainly impacts availabiilty and UX (e.g., delayed credits or withdrawals). Funds remain locked on the original chain; messaging failtures should not imply loss of funds, but operational reliability and integration monitoring still matter
* Locking smart contract: the origin-chain locking contract is a critical component
* Disclosure governance: “who can request or approve disclosure, under what policy, and how it’s audited” must be specified in deployments

## Links

* Fairblock docs (confidential transfers): <https://docs.fairblock.network/docs/confidential%5Ftransfers/confidential%5Ftransactions>
* Technical overview (architecture): <https://docs.fairblock.network/docs/confidential%5Ftransfers/technical%5Foverview>
* Stabletrust (UI / UX layer): <https://docs.fairblock.network/docs/confidential%5Ftransfers/stabletrust>
* FairyRing repo: <https://github.com/Fairblock/fairyring>

#### Referenced by

building blocks1
* [Origin-Locked Cross-Chain Confidential Ledger](/patterns/pattern-origin-locked-confidential-ledger/)

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