Implement WebAssembly cryptographic sandboxing for client signing

[Fatimasanusi]

Description

Handling private keys or complex cryptographic hashing directly in JavaScript exposes the client to memory scraping and XSS vulnerabilities.

Architecture & Context

To secure fractional asset redemptions, sensitive cryptographic operations must be isolated within a WebAssembly (Wasm) sandbox. The frontend should load a Rust-compiled Wasm module to handle signature verification and hash generation securely.

Technical Requirements

• Compile a minimal Rust cryptographic module to Wasm.
• Load the Wasm module asynchronously within the Next.js frontend.
• Expose secure signature verification functions to the TypeScript layer.

Acceptance Criteria

• Cryptographic operations execute strictly within the Wasm context.
• Wasm bundle size is optimized to under 500KB.
• Signature generation time is benchmarked to be faster than native JS.