Ethereum↔Polygon Bridge
Polygon brings you a trustless two-way transaction channel between Polygon and Ethereum by introducing the cross-chain bridge with Plasma and PoS security. With this users can transfer tokens across Polygon without incurring third-party risks and market liquidity limitations. The Plasma and PoS Bridge is available on both Mumbai Testnet as well as Polygon Mainnet.
Polygon bridge provides a bridging mechanism that is near-instant, low-cost, and quite flexible. Polygon uses a dual-consensus architecture(Plasma + Proof-of-Stake (PoS) platform) to optimise for speed and decentralization. We consciously architected the system to support arbitrary state transitions on our sidechains, which are EVM-enabled.
There is no change to the circulating supply of your token when it crosses the bridge;
- Tokens that leave the Ethereum network are locked and the same number of tokens are minted on Polygon as a pegged token (1:1).
- To move the tokens back to the Ethereum network, tokens are burned on Polygon network and unlocked on Ethereum network during the process.
PoS vs Plasma
| PoS Bridge(Recommended) | Plasma Bridge | |
|---|---|---|
| Short description | DApp Developers looking for flexibility and faster withdrawals with POS system security. | DApp Developers looking for increased security guarantees with Plasma exit mechanism. |
| Structure | Highly flexible | Rigid, Less Flexible |
| Deposit(Ethereum → Polygon) | 22-30 mins | 22-30 mins |
| Withdrawal(Polygon → Ethereum) | 1 checkpoint = ~ 30 mins to 6 hours | Call to the process-exit procedure on Ethereum's contract |
| Security | Proof-of-Stake system, secured by a robust set of external validators. | Polygon’s Plasma contracts piggybacks on Ethereum’s security. |
| Support Standards | ETH, ERC20, ERC721, ERC1155 and Others | Only ETH, ERC20, ERC721 |
The FxPortal is another type of bridge that is very similar to the PoS Bridge. They share the same characteristics as mentioned for PoS in the table above. The only difference is that Tokens need not be mapped on the FxPortal Bridge prior to bridging. The mapping happens during the first deposit transaction which is initiated for a given token. Also, anyone can make use of the FxPortal to build their own custom tunnels/bridges on top of the Polygon bridge. It is highly recommended to use the FxPortal for any bridging use case. New token mappings on PoS and Plasma will be discouraged post-Jan 31st, 2023 so that the mapping process is fully decentralized and flexible.