The audio link above presents a plan to improve the Cashu protocol, a system that allows Bitcoin users to send and receive payments privately, akin to using physical cash. It proposes using STARK proofs and a Proof of Liabilities (PoL) scheme to address the protocol's current reliance on trust in a central authority called the "mint". STARKs, which are a type of zero-knowledge proof, are touted for their efficiency, security, and transparency, enabling the mint to prove the validity of its actions without revealing sensitive information. The PoL scheme, in turn, introduces a mechanism for regularly auditing the mint's operations, preventing the mint from issuing more ecash tokens than it can redeem and enhancing accountability. It goes further, exploring the potential of integrating STARK proofs directly into the Bitcoin network using the OP_CAT opcode, enabling on-chain verification of the mint's actions and reducing reliance on off-chain trust. Finally, it also outlines different approaches to implement Cashu's logic using zero-knowledge techniques and highlights the benefits of using a specialised ZK domain-specific language like Cairo, as exemplified by a proof-of-concept implementation. The document concludes by emphasising the potential of this approach to bolster Cashu's security, increase transparency, and foster greater trustlessness within the Bitcoin ecosystem.