For ArS3nal, we needed a solution written in Rust that avoided these shortcomings while remaining fully compatible with the existing ecosystem. This was difficult for several reasons:

• •No Formal Specs: We had to build without formal specifications or interoperability tests.
• •Non-Standard Crypto: Aspects of Arweave's use of cryptography deviate from standards and required precise handling.
• •L2 Complexity: To guarantee maximum compatibility, we needed comprehensive support for L2 (Bundles).

Unrepresentable Invalid States: We used the type system to ensure invalid states cannot exist in the code.

• •Strict Access Control: We allow only specific, \"blessed\" methods for instantiating or converting certain types.
• •The Typestate Pattern: We used the typestate pattern to enforce the correct order of operations and safe state transitions.
• •Integrated Authentication: We treated data authentication as a core requirement enforced by the type system, not an afterthought.
• •Guarded Secrets: We placed key material behind specific "guard types." This prevents accidental disclosure and makes interaction with sensitive data intentional and easier to audit.