Bitcoin's scripting system is inherently limited in its programmability. Consequently, bridges to Bitcoin rely on multisigs and federation control, introducing trust. This has constrained Bitcoin's utility.
Recent advancements are enhancing programmability on Bitcoin. BitVM, its successors, and CatVM are enabling the verification of off-chain programs on Bitcoin through fraud proofs. This improves the current state of bridging on Bitcoin, minimizing the reliance on trusted multisig setups and federated bridges.
This report explores these recent advancements, including BitVM, CatVM, Lamport signatures, and the proposed OP_CAT opcode, along with their implications for trust-minimized bridging & zk-rollups on Bitcoin.