DahLIAS: First provably secure constant-size cross-input signature on secp256k1
Researchers Jonas Nick, Tim Ruffing (Blockstream Research) and Yannick Seurin (Ledger) published DahLIAS, the first formal, provably secure construction of a constant-size, fully aggregated cross-input signature scheme that operates on Bitcoin’s native secp256k1 curve. DahLIAS produces a single 64-byte signature that aggregates signatures from many signers across different transaction inputs (CISA), reducing transaction size and verification cost. Unlike BLS-based aggregation, DahLIAS works within Bitcoin’s existing curve assumptions and requires only similar cryptographic premises already used by Bitcoin. It uses a two-round interactive protocol (similar in interaction to MuSig2 but functionally distinct) and includes formal security proofs. DahLIAS is not compatible with current Bitcoin consensus rules as-is — verification takes a set of public keys and corresponding messages plus a 64-byte proof rather than the single public key–message–signature model — so integrating it would require a consensus change and a BIP. The paper’s key contribution is demonstrating that full cross-input signature aggregation on secp256k1 is possible, paving the way for future BIP proposals and implementation work (e.g., secp256k1lab) to bring smaller, more private and cheaper complex transactions to Bitcoin.
Neutral
DahLIAS is primarily a technical advancement rather than an immediate market-moving event. It demonstrates that constant-size cross-input signature aggregation on secp256k1 is possible, which could materially reduce Bitcoin transaction sizes and verification costs if adopted. In the short term, the news is unlikely to change price action because DahLIAS requires a consensus-level protocol change (BIP and client support) before it affects on-chain economics and fees. Traders typically react strongly to events that immediately affect supply, demand, or regulatory status; this paper does not. In the medium to long term, however, successful implementation and adoption could be bullish for Bitcoin fundamentals: lower fees and cheaper CoinJoin-style privacy transactions could increase on-chain utility and privacy, improving demand and network decentralization (lower verification cost encourages more full-node operation). Historical parallels: protocol research (e.g., Schnorr/Taproot) often causes initial neutral market reaction upon publication but becomes bullish after standardization and activation. Therefore expect neutral immediate impact, with potential long-term bullish implications contingent on adoption, BIP progress, and developer/community support.