Function build_proof 

pub fn build_proof(
    mode: AshMode,
    binding: &str,
    context_id: &str,
    nonce: Option<&str>,
    canonical_payload: &str,
) -> Result<String, AshError>

Build a cryptographic proof for request integrity.

The proof is computed as:

proof = BASE64URL(SHA256(
  "ASHv1\n" +
  mode + "\n" +
  binding + "\n" +
  contextId + "\n" +
  (nonce + "\n" if present) +
  canonicalPayload
))

Arguments

• mode - Security mode (minimal, balanced, strict)
• binding - Canonical binding (e.g., “POST /api/update”)
• context_id - Context ID from server
• nonce - Optional nonce for server-assisted mode
• canonical_payload - Canonicalized payload string

Example

use ash_core::{build_proof, AshMode};

let proof = build_proof(
    AshMode::Balanced,
    "POST /api/profile",
    "ctx_abc123",
    None,
    r#"{"name":"John"}"#,
).unwrap();

println!("Proof: {}", proof);