Taproot Wizards, known for their innovative work in the Bitcoin ecosystem, recently released a cartoon called CatVM that contains valuable technical insights on scaling proposals. The cartoon, while whimsical in nature, introduces a new mechanism for moving in and out of scaling layers built on top of Bitcoin.
The cartoon introduces two key building blocks: Rijndael’s OP_CAT experiment and the ability to verify merkle tree branches using OP_CAT. These building blocks enable a unilateral withdrawal mechanism from a shared UTXO, allowing users to withdraw their funds independently with the guarantee that the remaining funds are still accessible to others.
Additionally, the cartoon explores the concept of BitVM, which allows for locking bitcoin with more complicated conditions than supported by Bitcoin script. The use of OP_CAT in conjunction with BitVM enables the enforcement of locking conditions supported by a second layer that are not directly supported by Bitcoin script.
However, the design presented in the cartoon is incomplete in terms of construction and requires further development, such as the addition of an opcode like OP_ZKVERIFY to update merkle tree roots representing user balances off-chain in a trustless manner.
Overall, the CatVM cartoon presents a promising concept for facilitating unilateral withdrawals and enhancing the flexibility and programmability of funds in the Bitcoin ecosystem. While concrete demos may not be imminent, the idea is certainly worth considering for future development in the space.
