Key Highlights
- Ripple has recommended withdrawing XLS-38, the XRP Ledger’s proposed XChainBridge amendment, along with the related fixXChainRewardRounding amendment.
- XLS-38 was designed to enable native cross-chain bridges on XRPL using a decentralized network of witness servers to verify transactions across chains.
- Ripple concluded that the witness-server model creates security, decentralization, and operational trade-offs that become more significant as the value locked in a bridge increases.
Ripple, a private technology company, has recommended that the XRP Ledger community withdraw the XChainBridge amendment, known as XLS-38, along with the related fixXChainRewardRounding amendment.
According to the recommendation outlined in a blog post by a Ripple engineer, XLS-38 was originally proposed to enable native cross-chain bridges on the XRP Ledger. It defined a protocol using a decentralized network of witness servers to observe and attest to transactions across chains.
The design aimed to support custom sidechains, including private chains, permissioned networks, and experimental environments, as well as a bridge between the XRPL EVM sidechain and the mainnet with XRP as the native gas token.
Background on bridging approach
As preparation advanced for the XRPL EVM Sidechain, a collaboration involving Peersyst, Ripple and the broader XRPL community, an evaluation of bridging options took place. The review examined security, user experience, decentralization and long-term operational sustainability.
The XLS-38 witness server model was assessed as presenting trade-offs between security and decentralization that increase with the value locked in a bridge. Accountability and coordination become more complex as the set of witness operators expands. Ripple concluded that operating such a bridge for a public chain’s native gas token was outside its core operational expertise at scale.
Axelar was selected for the XRPL EVM Sidechain bridge. The network operates with more than 75 validators, a threshold signature scheme, and established key-rotation practices. It supports bridging across more than 55 blockchains.
In June 2024, the decision to use Axelar was announced. At that time, the XLS-38 amendment was left available for a vote while Ripple’s Unique Node List validator continued to vote against it. A period of 12 to 15 months was provided for the community to demonstrate interest in XLS-38 for private sidechain use cases.
Observations during the review period
That period has now ended. During the interval, Ripple engaged with developers, monitored community forums and reviewed projects or proposals that would rely on an activated XLS-38 bridge on mainnet. The level of adoption or developer interest observed did not reach the threshold that would support continued movement toward activation.
Several factors informed the recommendation. The EVM Sidechain bridge is addressed by the Axelar integration. No significant demand materialized for private sidechains that would specifically use XLS-38. Maintaining the inactive code in xrpld was identified as creating an ongoing maintenance burden and a source of potential confusion for new contributors. Withdrawing the amendment would allow removal of more than 10,000 lines of code from xrpld.
The recommendation is not a unilateral decision. Ripple controls one vote among many on the XRPL. The firm stated it remains open to revisiting the assessment if developers or organizations present concrete plans or active projects that rely on XLS-38.
Proposed withdrawal process
If the community supports the direction, the process would proceed in stages. The first step would be a pull request to the xrpld repository setting VoteBehavior::Obsolete for the XChainBridge feature. Once merged, servers running that version would automatically vote against the amendment.
As validators upgrade, support for the amendment would decline. Once all active validators treat it as obsolete, the code for XChainBridge and fixXChainRewardRounding could be removed in a subsequent update.
Implications for network participants
For users of the XRPL EVM Sidechain, the Axelar bridge remains the connection to and from the XRPL mainnet. Validators would see automatic changes in voting behavior upon upgrading to a version that includes the Obsolete setting. Contributors to xrpld would review the proposed changes through the normal open-source process.
Developers who had been exploring XLS-38 for private sidechains were invited to share use cases through the XRPL developer Discord or GitHub.
Related XRPL amendment activity
In a separate development earlier this year, Doppler Finance outlined how the proposed XLS-66 amendment could support institutional on-chain lending on the XRP Ledger. That proposal focuses on native lending functionality with uncollateralized, fixed-term structures and off-chain underwriting, distinct from the cross-chain bridging design of XLS-38.
A comment period remains open on the XChainBridge recommendation before any further steps.
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