The rn-ldk implementation brings an open-source lightweight Lightning node to React Native, a popular programming language for developing mobile applications. It is powered by LDK, a flexible Lightning implementation written in the Rust programming language.
One feature BlueWallet will provide its users with the new integration, which is demonstrated in the announcement, is the ability to open and fund a Lightning channel from their mobile phones directly from an offline, air-gapped hardware wallet — leveraging Partially Signed Bitcoin Transactions (PSBTs).
PSBTs are a standard defined in BIP174 that allows two or more people or devices to collaborate in creating, funding, signing and broadcasting a Bitcoin transaction. At its core, PSBTs make it possible for people to more freely pass around a transaction, update its details and sign it once it’s ready to be sent. As a result, it allows for air-gapped devices to participate in signing the transaction, for instance, letting an online client such as BlueWallet broadcast it.
Another feature relates to backing up Lightning channels managed by the wallet. The company shared that encrypted backups can be stored in the cloud, allowing the user to more quickly restore their Lightning wallet and all of its channels on another device through a mnemonic backup phrase.
The go-to server infrastructure utilized by BlueWallet’s new implementation is Electrum, which it uses to quickly synchronize with the Bitcoin blockchain. Although Electrum is a reasonably popular and established solution, this process leaks user addresses to the Electrum server bridging the user’s mobile wallet with the Bitcoin peer-to-peer network. As a result, it effectively hurts user privacy and sovereignty as a third party would be in charge of validating transactions.