The Chaumian ecash tokens support privacy-preserving and partially offline payments, with Cashu [1] being its concrete implementation. The Cashu coordination service called 'Mint' is responsible for issuance and reimbursement of ecash tokens and providing liquidity connection with the outer world, typically via on-chain or Lightning payment protocols. As the Mint must always be online and controls access to underlying digital assets, it presents a value attack target. JCMint [2] is a set of protocols and a prototype implementation for realizing sensitive Mint operations inside a cryptographic smartcard with optional support for a multiparty variant further distributing sensitive operations over multiple smartcards.

The goal of this thesis is to:

• Extend the original JCMint implementation to be compatible with the current version of Cashu specifications.  
• Port Mint's sensitive operations to the Trezor wallet hardware platform using the Signatory interface, providing support for alternative hardware protection platforms, and providing an easy-to-deploy package.
• Systematically evaluate the performance of Min operations on Trezor and compare it to JCMint.
• Discuss options for further hardening of sensitive operations of the Cashu ecosystem, using systematic enumeration of involved components and examination of possible attack scenarios.