SendSure Rust MVP

SendSure is a wallet-agnostic, intent-aware transaction preflight safety layer. A user states what they intend to send, swap, approve, or sign; SendSure compares that intent with a proposed transaction draft and returns READY, REVIEW, or STOP.

The wallet remains responsible for custody and signing. SendSure never requests, collects, stores, or processes seed phrases or private keys.

Current implementation summary

• Deterministic Rust engine with transfer, swap, approval, signature, and security checks.
• In-memory registries that include XRP Ledger, Ethereum, Base, BNB Smart Chain, Stellar, XRP on XRP Ledger, XLM on Stellar, USDC on Ethereum and Base, and ETH on Ethereum and Base.
• XRP deposit tags and memos are resolved from the in-memory deposit registry when the destination matches the Demo Exchange XRP deposit profile.
• Slippage is evaluated with the requested thresholds: 0% through 3% is READY, greater than 3% through 10% is REVIEW, and greater than 10% is STOP.
• Deterministic STOP rules cover empty SEND/SWAP destination addresses, seed-phrase requests, and private-key requests.
• Twenty-one regression tests cover the seven demo scenarios, tag handling, slippage thresholds, unlimited approvals, trusted/unknown contracts, empty addresses, sensitive-key requests, and split HTTP request bodies.

What is implemented

• Deterministic Rust safety engine for transfers, tokens, swaps, signatures, approvals, and wallet-security education hooks.
• Chain-neutral Intent model designed for a future frontend or wallet adapter.
• STOP-over-REVIEW-over-READY decision precedence.
• In-memory registries for networks, tokens, exchanges, deposit profiles, and contracts.
• Seven polished demo scenarios in the required order.
• Unit/integration tests for the core rules and demo summary.
• Lightweight Rust HTTP server with a plain HTML/CSS/JavaScript interface.

Deterministic safety rules

SendSure uses local Rust rules only. It does not use an LLM, external risk service, blockchain API, internet request, database, paid API, authentication system, smart contract, browser extension, or live wallet connection to make decisions.

Current primary rules include:

Rule ID	Decision	Purpose
TRANSFER_DESTINATION_TAG_MISMATCH	STOP	Entered destination tag/memo differs from the expected exchange deposit tag/memo.
TRANSFER_MISSING_DESTINATION_TAG	STOP	A required destination tag/memo is absent.
TRANSFER_EMPTY_DESTINATION_ADDRESS	STOP	SEND or SWAP requests omit a destination address.
SECURITY_SEED_OR_PRIVATE_KEY_REQUEST	STOP	The request appears to seek a seed phrase or private key.
TOKEN_UNSUPPORTED_DESTINATION_NETWORK	STOP	Asset is not supported on the chosen destination network in the registry.
TOKEN_UNKNOWN_FAMILIAR_SYMBOL	STOP	Unknown token uses a familiar symbol such as USDC.
SIGN_UNEXPECTED_AIRDROP_INTERACTION	STOP	Signature touches an unsolicited or unexpected airdrop contract.
APPROVAL_MISSING_SCOPE	STOP	Approval amount/scope is missing, blank, or unknown.
APPROVAL_UNLIMITED_ALLOWANCE	STOP	Approval grants unlimited/infinite/max/uint256::MAX allowance.
SWAP_MISSING_SLIPPAGE	REVIEW	Swap is missing slippage tolerance, so risk check is incomplete.
SWAP_SLIPPAGE_REVIEW	REVIEW	Swap slippage is greater than 3% through 10%.
SWAP_SLIPPAGE_STOP	STOP	Swap slippage is greater than 10%.
READY_INTENT_MATCH	READY	No deterministic warning or stop rule fired.

Corrected primary XRP scenario

The demo registry includes a fictional deposit profile:

• Exchange: Demo Exchange
• Network: XRP Ledger
• Destination address: rDemoExchangeAddress
• Expected destination tag: 482901
• Entered destination tag in the mismatch scenario: 482109
• Result: STOP
• Rule ID: TRANSFER_DESTINATION_TAG_MISMATCH

Explanation displayed by the engine:

The destination tag does not match the expected deposit tag for this account. Do not send until the deposit details are verified.

A separate missing-tag test validates TRANSFER_MISSING_DESTINATION_TAG, and a registry-derived expected tag path verifies the deposit registry is used as the trusted source.

Demo scenarios

cargo run prints these seven scenarios in order:

1. XRP destination tag mismatch → STOP
2. USDC unsupported destination network → STOP
3. Unknown token using a familiar symbol → STOP
4. Unexpected airdrop interaction → STOP
5. Unlimited approval → STOP
6. High-slippage swap at 7% → REVIEW
7. Valid XRP with the correct destination tag → READY

Expected final summary:

STOP: 5
REVIEW: 1
READY: 1
Total scenarios: 7

Intent model

The reusable Intent struct supports:

• action type: SEND, SWAP, APPROVE, SIGN
• source network
• destination network
• asset symbol
• token or asset identifier
• destination address
• expected destination address
• entered destination tag or memo
• expected destination tag or memo
• contract address
• approval amount or approval scope
• swap slippage
• transaction origin
• whether the asset was unsolicited

Run locally

cargo fmt
cargo test
cargo clippy -- -D warnings
cargo run

Web server

Start the lightweight server:

cargo run -- serve

Open http://127.0.0.1:8080/.

Routes:

• GET /health returns server health JSON.
• GET /api/scenarios returns the seven demonstration scenarios.
• POST /api/evaluate accepts an Intent JSON body and returns a Rust engine evaluation.

Example evaluation request:

curl -s http://127.0.0.1:8080/api/evaluate \
  -H 'content-type: application/json' \
  -d '{"action_type":"SEND","source_network":"xrpl","destination_network":"xrpl","asset_symbol":"XRP","asset_identifier":"xrp:xrp","destination_address":"rDemoExchangeAddress","expected_destination_address":"rDemoExchangeAddress","entered_destination_tag_or_memo":"482109","expected_destination_tag_or_memo":"482901","contract_address":null,"approval_amount_or_scope":null,"swap_slippage_percent":null,"transaction_origin":"Demo Exchange","asset_was_unsolicited":false}'

The browser JavaScript only collects input and displays API responses. It does not calculate or override safety decisions. For STOP results, the SendSure Continue button is disabled. SendSure does not claim it can block actions performed outside the application.

Roadmap / not added yet

• Live wallet connections
• WalletConnect or Reown
• Stellar Wallets Kit
• Xaman SDK
• Live blockchain transactions
• Real funds
• Paid APIs or Alchemy integration
• Authentication or database
• Browser extension
• Smart contracts
• LLM risk decisions
• React or another large frontend framework