> ## Documentation Index
> Fetch the complete documentation index at: https://docs.pfbridge.xyz/llms.txt
> Use this file to discover all available pages before exploring further.
# ProofBridge vs. other cross-chain bridges
> Side-by-side comparison of ProofBridge against CCTP, Houdini Swap, and validator-based bridges (Allbridge, Wormhole, Stargate, LayerZero) across custody, intermediaries, and settlement.
Cross-chain bridges typically share one of three structural trade-offs: funds flow through a central pool that becomes a honeypot, an external validator set or attestation service approves transfers and becomes a trust assumption, or transactions route through intermediaries the user has to trust. ProofBridge takes a different approach — users hold their own assets in protocol escrow, the two parties on a trade are the only participants, and settlement is gated by an on-chain zero-knowledge proof.
The table below compares the design choices across the protocols ProofBridge is most often measured against.
## Feature comparison
| Feature | ProofBridge | CCTP (coming to Stellar) | Houdini Swap (privacy pools) | Allbridge / Wormhole / Stargate / LayerZero |
| ---------------------------------------------------- | :---------------------------------------------------: | :-----------------------------: | :---------------------------------------------: | :-----------------------------------------: |
| User holds custody throughout the transfer | ✅ (self-custodied protocol escrow, unlocked by proof) | ❌ | ❌ (custodied by centralized exchanges mid-swap) | ❌ |
| Only the two trading parties participate | ✅ | ❌ | ❌ (routes through CEXes + a Monero hop) | ❌ |
| No external validators, attestors, or intermediaries | ✅ | ❌ (Circle's Iris attestation) | ❌ (centralized exchanges) | ❌ (guardians / relayers / oracles) |
| Peer-to-peer consensus (BLS) | ✅ | ❌ | ❌ | ❌ |
| Zero-knowledge proof verification on-chain | ✅ | ❌ | Partial (privacy proofs, not settlement) | ❌ |
| Censorship-neutral by design | ✅ | ❌ (Circle can refuse to attest) | ❌ (a CEX in the route can refuse the swap) | ❌ (validators can refuse to sign) |
| Asset coverage | Any ERC-20 / SAC / SEP-41 / native | USDC only | Subset routed through privacy pools | Broad, validator-curated |
| Settles in minutes | ✅ | ✅ (V2 Fast Transfer: \~30s) | Variable (depends on CEX clearing) | ✅ |
## What each row means
### User holds custody throughout the transfer
On ProofBridge, a Bridger's deposit lives in the `OrderPortal` contract on the source chain and a Maker's liquidity lives in their own ad inside `AdManager`. Neither is a pooled vault, and neither is held by an operator. A compromise of one account does not spread to other users.
CCTP burns and re-mints USDC under Circle's issuance authority. Houdini Swap routes funds through centralized exchanges mid-swap, so those exchanges custody the assets in transit. Validator-based bridges route every transfer through a shared pool or multisig — a single compromise drains everyone.
### Only the two trading parties participate
A ProofBridge trade has exactly two participants: the Maker and the Bridger. There is no operator entity, no liquidity aggregator, and no centralized routing layer in the path. The contracts enforce the rules; the relayer is a courier that submits proofs and cannot authorize anything.
Houdini Swap, by contrast, is a swap aggregator — funds pass through centralized exchanges and a Monero hop to achieve privacy. CCTP and validator bridges have their own off-chain machinery (attestation service, guardian set, relayer network) sitting between the two ends.
### No external validators, attestors, or intermediaries
ProofBridge does not depend on a third-party validator set or attestation service. In the BLS end-state, the only signers on a trade are the two counterparties themselves.
* **CCTP** requires Circle's Iris attestation service to sign off before a mint can happen on the destination chain.
* **Houdini Swap** routes through centralized exchanges, each of which is an intermediary in the trust path.
* **Allbridge, Wormhole, Stargate, LayerZero** route transfers through an external validator set (Allbridge's validator network, Wormhole guardians, LayerZero relayers and oracles) that must sign off before funds move.
Each of those is a trust assumption and an attack target. ProofBridge replaces them with cryptographic proof.
### Peer-to-peer consensus (BLS)
ProofBridge settles because the Maker and Bridger co-sign the trade with BLS signatures, aggregated into a single compact proof of agreement. Consensus is between the two parties on the trade — no external quorum, no committee, no aggregator.
### Zero-knowledge proof verification on-chain
Every settlement on ProofBridge includes a ZK proof that the counterparty's deposit is genuinely recorded on-chain (MMR inclusion), that the order hash matches the agreed terms, and that the nullifier has not been used. The on-chain Verifier checks the proof before any funds move.
ProofBridge uses ZK proofs for **verification, not privacy** — the proof attests to the correctness of the cross-chain state, while order amounts, recipients, and Merkle roots remain public on-chain. Houdini Swap uses zero-knowledge primitives for the opposite purpose: hiding the link between source and destination. CCTP and validator bridges rely on attestations rather than cryptographic proofs of deposit at all.
### Censorship-neutral by design
ProofBridge contracts cannot tell who is behind a wallet, and no party in the protocol can refuse a valid trade. CCTP can refuse to attest a transfer (sanctions, compliance, key compromise). A centralized exchange in a Houdini route can refuse the swap. Validators in a validator-based bridge can refuse to sign.
### Asset coverage
ProofBridge bridges any ERC-20, Stellar Asset Contract, SEP-41 token, or native asset that a Maker provides liquidity for — including the long tail of anchor-issued Stellar assets. CCTP handles USDC only. Houdini Swap handles the subset of assets its privacy pools route. Validator-based bridges have broad coverage but it is validator-curated.
### Settles in minutes
ProofBridge settles as soon as both deposits are proven and both `unlock` calls confirm — typically a few minutes, faster once the BLS phase removes the relayer round-trip. CCTP's V2 Fast Transfer is sub-minute for USDC. Houdini Swap's timing depends on the centralized exchanges in the route clearing. Validator-based bridges are generally minutes once their quorum signs.
## Where each approach makes sense
No bridge design is universally best. The table above is specifically about **the security and trust model**, which is what ProofBridge was built to address.
You want to retain custody of your assets, you cannot accept a shared-pool honeypot, an off-chain attestor, or a centralized-exchange intermediary in your threat model, and you need proof-based settlement. Particularly relevant for the long tail of Stellar assets and for institutional or sanctions-sensitive flows.
You need USDC↔USDC bridging and Circle's attestation service is acceptable in your trust path. CCTP is the right default for that corridor — deep liquidity, sub-minute settlement on V2 Fast Transfer, low cost. ProofBridge and CCTP serve different problems; both belong in the Stellar ecosystem.
Transactional privacy is a primary requirement — you specifically want to break the on-chain link between source and destination. ProofBridge does not do this; it is a verification protocol, not a privacy protocol.
You need extremely broad chain coverage today and your threat model accepts a validator set as a trust anchor. Those bridges ship on more chains faster because adding a validator is cheaper than deploying a full proof system.
## Further reading
The problem statement and the protocol's response to it.
Why ProofBridge uses ZK for cross-chain verification rather than privacy.
Exact trust assumptions under the current pre-auth phase and under BLS.
The architecture and 12-step cross-chain flow.