SignShield

See what you sign — before you sign it.

SignShield decodes Ethereum transactions into human intent: approvals, transfers, swaps, multicalls, NFT operators — and flags drainer patterns before you click Sign in your wallet.

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Why SignShield?

Problem	SignShield
Wallet shows raw hex	Plain English intent
Drainers hide in multicall	Inner action detection
Infinite approve scams	CRITICAL before you sign
No offline tool	CLI + demo UI, no API key

Part of the FounderB security stack: FluxTap watches the wire · Tracefuse watches what you ship · SignShield watches what you sign.

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60-second demo

git clone https://github.com/FounderB/SignShield.git
cd SignShield
cargo build --release

# malicious infinite approve → Do NOT sign
./target/release/signshield analyze --file examples/malicious-approve.json

# optional RPC simulation (eth_getCode + eth_estimateGas)
./target/release/signshield analyze --file examples/malicious-approve.json --rpc https://eth.llamarpc.com

# safe ERC-20 transfer
./target/release/signshield analyze --file examples/safe-transfer.json

# cinematic web UI
./target/release/signshield serve
# → http://127.0.0.1:8787

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CLI

signshield analyze --file tx.json          # human report
signshield analyze --file tx.json --json   # machine output
signshield analyze --file tx.json --fail-on-risk  # exit 1 if risky
signshield analyze --file tx.json --rpc $SIGNSHIELD_RPC  # simulate via JSON-RPC
signshield analyze-typed --file examples/malicious-permit.json
signshield reputation                       # feed stats
signshield update-reputation                # fetch latest feed
signshield wc-bridge --project-id $WALLETCONNECT_PROJECT_ID  # WC middleware

signshield decode --data 0x095ea7b3...
signshield explain infinite_approve
signshield rules
signshield init   # writes .signshield.toml (loaded for high_eth_wei + reputation cache)
signshield serve --addr 127.0.0.1:8787

Transaction JSON shape

{
  "from": "0x...",
  "to": "0x...",
  "value": "0x0",
  "data": "0x095ea7b3...",
  "chain_id": 1
}

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Detectors (v0.6)

Rule	Severity	What it catches
reputation_malicious	CRITICAL	Address in SignShield reputation feed
infinite_approve	CRITICAL	Unlimited ERC-20 allowance
zero_address	CRITICAL	Zero address in tx or calldata
multicall_hidden_transfer	CRITICAL	Approve/transfer buried in batch
nft_operator_all	CRITICAL	setApprovalForAll
phishing_typed_data	CRITICAL	Fake Mail/Login typed data drains
permit2_signature	WARN	Off-chain spend authorization via Permit2
eip2612_permit	WARN	On-chain EIP-2612 permit (0xd505accf)
typed_data_permit	WARN	EIP-712 Permit / Permit2
permit2_batch	WARN	Multiple token permissions in one sign
increase_allowance	WARN	Persistent allowance bump
high_eth_outflow	WARN	Large native transfer
call_to_eoa_with_data	WARN	Calldata to EOA (RPC)
simulation_revert	WARN	eth_estimateGas failed (RPC)
rpc_url_blocked	WARN	SSRF-safe RPC URL rejected
balance_snapshot	INFO	Live ETH/token balance via RPC
trusted_contract	INFO	Known protocol (Uniswap, Permit2, …)
siwe_login	INFO	Sign-In With Ethereum auth
seaport_order / blur_order	INFO	NFT marketplace orders

Reputation feed: data/reputation.json — auto-updated in extension every 6h.

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WalletConnect middleware (v0.6)

Guard mobile wallet connections from desktop dApps:

dApp ──WC──► SignShield ──analyze──► MetaMask / Rabby

export WALLETCONNECT_PROJECT_ID=…   # free at https://cloud.reown.com
signshield wc-bridge
# 1. Scan QR with your wallet
# 2. Paste dApp wc: URI at http://127.0.0.1:8789
# 3. Approve/reject each request in UI

See bridge/walletconnect/README.md.

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Chrome extension (v0.6)

Guard MetaMask/Rabby before sign:

chrome://extensions → Developer mode → Load unpacked → SignShield/extension/

Hooks window.ethereum, WalletConnect providers, typed data, legacy send/sendAsync · overlay on risky txs · optional RPC simulate · trusted domains · extension/README.md

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Security notes (v0.6.1)

• Demo /api/examples/{name} only serves simple *.json basenames under examples/
• Optional --rpc / ?rpc= URLs must be http(s); private, link-local, and cloud-metadata hosts are blocked
• Default analyze path stays offline — RPC is opt-in

See SECURITY.md.

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License

MIT © FounderB — see LICENSE.

Don't sign what you can't read.