# Private stablecoin wallet: privacy, custody and risks

We did not want “secure” to quietly stand in for “private.” A wallet can protect access while a public blockchain still reveals balances, timing and relationships between addresses.

> THE SHORT ANSWER: Fiber uses zero-knowledge proofs to protect supported transfers, trades and earn activity through infrastructure based on a fork of Railgun. That privacy applies inside a defined Fiber flow; public blockchains and integrated banking or card services keep their own visibility and data practices.

- In Fiber, security protects access while privacy limits what others can observe.
- We use cryptographic privacy, not address rotation dressed up as privacy.
- Zero-knowledge proofs verify supported activity without publishing its private inputs.
- Our privacy layer cannot rewrite the data practices of every integrated service.

## Why Fiber separates security from privacy

Security is about preventing unauthorized access to your Fiber account. Privacy is about limiting what outside observers can learn from supported activity. We treat them as separate requirements because a wallet can protect its keys while every transfer remains visible on a public ledger.

Public visibility can include amounts, timing, counterparties and the history connected to a reused address. Legal names may not appear on-chain, but public data and off-chain information can still connect the activity to people and businesses.

## How Fiber proves activity without publishing it

A zero-knowledge proof lets one party prove that a transaction follows the system’s rules without revealing the private information used to create the proof.

Fiber applies that idea to supported transfers, trades and earn activity through infrastructure based on a fork of Railgun. The proof establishes that supported activity is valid while keeping its private financial inputs out of the public record.

## The questions we expect you to ask us

“Private” should describe a system, not set a mood. When you evaluate Fiber or another wallet, ask which assets and actions are supported, when the protected flow begins and ends, what appears publicly and what an integrated provider can still observe.

- Which balances and transaction details are shielded?
- Which chains, assets and actions are supported?
- What data can the interface or provider observe?
- What happens when funds interact with a public address?
- Do integrated services apply separate verification requirements?

## Where Fiber’s privacy boundary ends

We cannot rewrite the data practices of every bank, card issuer, exchange, blockchain or integrated service. Moving funds into or out of Fiber’s protected flow can create public or provider-visible events.

So we do not describe Fiber as universally invisible. Privacy applies to supported Fiber activity, and we state the relevant boundary beside the feature it affects.

## Questions worth asking before the money moves.

### Are stablecoin transactions private by default?

Not usually. Public blockchains generally record inspectable transaction data even when addresses are pseudonymous. Fiber adds zero-knowledge privacy to supported activity.

### Does a new wallet address make a transfer private?

No. A new address can reduce simple reuse, but transaction graphs and off-chain information can still connect activity. Fiber relies on zero-knowledge proofs for supported private activity instead.

### Does Fiber hide every transaction everywhere?

No. We protect supported Fiber activity. Public blockchain interactions and integrated third-party services have their own visibility and data practices.

## Sources

- [Railgun: Privacy system overview](https://docs.railgun.org/wiki)
- [CFPB: Public-ledger identification risks](https://www.consumerfinance.gov/archive/newsroom/cfpb-publishes-new-bulletin-analyzing-rise-in-crypto-asset-complaints/)

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Fiber is a financial technology company, not a bank. Banking services are provided by SSB, Member FDIC. Funds deposited at SSB are eligible for FDIC insurance up to $250,000 per depositor, per insured bank, subject to applicable limitations and FDIC rules.