Developer Unveils Lichen Design for Trust-Minimized Bitcoin Layer-2 Exits

Developer Adam Gibson presented a paper and proof-of-concept implementation for Lichen, a protocol enabling users to withdraw funds from a single-issuer Bitcoin layer 2 without relying on the issuer's cooperation ¹. Gibson posted the design to the Bitcoin-Dev mailing list ¹. At the time of writing, $BTC traded around $81,484.

Under the Lichen architecture, a central entity dubbed a "hub" mints tokens pegged one-to-one to bitcoin on a layer-2 ledger maintained by a separate sequencer ¹. Users deposit funds by locking $BTC into an individual 2-of-2 output shared with the hub, receiving corresponding tokens to execute off-chain transfers ¹. To mirror inbound liquidity models found in the Lightning Network, the hub commits its own capital up to a negotiated cap in the output, allowing recipients to withdraw received tokens onchain ¹. In standard operations, the hub cooperatively signs redemption transactions; if the hub refuses or becomes unresponsive, the user submits a Groth16 proof demonstrating that the sequencer logged the token return ¹. Because native Bitcoin Script cannot parse these zero-knowledge proofs directly, Lichen settles disagreements onchain using presigned BitVMX transactions that reduce the dispute to a single evaluable execution step ¹.

Off-Chain Tradeoffs and Wallet Updates

Lichen removes the need for honest-majority attestation committees used in architectures like LN-GAP, shifting dispute resolution entirely to base-layer scripts enforced by collateral bonds ¹. Both parties lock financial reserves that are forfeited upon losing a challenge ¹. However, Gibson noted residual security constraints: users still rely on the sequencer to process ledger updates honestly ¹. An adversarial or malfunctioning sequencer could fail to register token returns or attest to unreached states, resulting in capital loss for users or the hub ¹.

Alongside the Lichen proposal, the Bitcoin development ecosystem saw several complementary infrastructure updates. Contributor João Dias submitted a Delving Bitcoin proposal extending BIP379 miniscript syntax to support private hash preimages directly within Bitcoin Core descriptors, removing external tool dependencies for pre-known secrets ¹. Concurrently, developers shipped security patches across versions 0.14.4 and 0.14.5 of the Eclair Lightning client to mitigate trampoline routing exploits and signature verification bugs in taproot channel splicing ¹.