signature-replay-analysis

Name: signature-replay-analysis
Author: quillai-network

114stars23forks

How to install signature-replay-analysis?

quillai-network/quillshield_skills/signature-replay-analysis

$npx -y skills add quillai-network/quillshield_skills --skill signature-replay-analysis

Installs into the current project.

Summary

Detects signature replay vulnerabilities in smart contracts — affecting 19.63% of signature-using contracts. Covers five replay types (same-chain, cross-chain, cross-contract, nonce-skip, expired-signature), EIP-712 domain separator verification, nonce management analysis, ecreco

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SKILL.md

1	# Signature & Replay Analysis
2
3	Detect vulnerabilities where cryptographic signatures can be reused, replayed across chains/contracts, or exploited through implementation flaws. Research shows 19.63% of Ethereum contracts using signatures contain replay vulnerabilities.
4
5	## When to Use
6
7	- Auditing contracts that verify signatures (`ecrecover`, ECDSA, EIP-712)
8	- Reviewing ERC-20 `permit()` / Uniswap Permit2 implementations
9	- Analyzing meta-transaction / gasless relay systems
10	- Verifying multi-sig signature aggregation
11	- Checking off-chain order books or signed message execution
12
13	## When NOT to Use
14
15	- Contracts without any signature verification
16	- Pure on-chain access control (use semantic-guard-analysis)
17	- Token standard compliance (use external-call-safety)
18
19	## Core Concept: The Signature Trust Model
20
21	A signature proves that a specific private key holder authorized a specific action. For this to be secure, the signature must be:
22
23	1. Bound to context — specific chain, contract, and version (domain separation)
24	2. Used exactly once — nonce prevents replay
25	3. Time-limited — deadline/expiry prevents late execution
26	4. Correctly verified — ecrecover edge cases handled
27
28	Any gap in this model creates a replay vulnerability.
29
30	## The Five Replay Types
31
32	### Type 1: Same-Chain Replay
33
34	The exact same signature is submitted multiple times to the same contract on the same chain.
35
36	```solidity
37	// VULNERABLE: No nonce — same signature works forever
38	function executeWithSig(address to, uint256 amount, bytes memory signature) external {
39	bytes32 hash = keccak256(abi.encodePacked(to, amount));
40	address signer = ECDSA.recover(hash, signature);
41	require(signer == admin, "Invalid signer");
42	token.transfer(to, amount);
43	// Attacker can submit this same signature again and again!
44	}
45
46	// SAFE: Use nonce
47	mapping(address => uint256) public nonces;
48
49	function executeWithSig(address to, uint256 amount, uint256 nonce, bytes memory signature) external {
50	require(nonce == nonces[admin], "Invalid nonce");
51	bytes32 hash = keccak256(abi.encodePacked(to, amount, nonce));
52	address signer = ECDSA.recover(hash, signature);
53	require(signer == admin, "Invalid signer");
54	nonces[admin]++;
55	token.transfer(to, amount);
56	}
57	```
58
59	### Type 2: Cross-Chain Replay
60
61	A signature valid on one chain (e.g., Ethereum) is replayed on another chain (e.g., Polygon, Arbitrum) where the same contract is deployed.
62
63	```solidity
64	// VULNERABLE: No chainId in signed message
65	bytes32 hash = keccak256(abi.encodePacked(to, amount, nonce));
66	// This hash is identical on Ethereum, Polygon, Arbitrum, etc.
67
68	// SAFE: Include chainId (via EIP-712 domain separator)
69	bytes32 DOMAIN_SEPARATOR = keccak256(abi.encode(
70	keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"),
71	keccak256(bytes("MyContract")),
72	keccak256(bytes("1")),
73	block.chainid,
74	address(this)
75	));
76	```
77
78	### Type 3: Cross-Contract Replay
79
80	A signature for Contract A is replayed on Contract B (same chain) if both accept the same message format without contract-specific binding.
81
82	```solidity
83	// VULNERABLE: No contract address in signed message
84	bytes32 hash = keccak256(abi.encodePacked(to, amount, nonce, block.chainid));
85	// Same hash for any contract on this chain
86
87	// SAFE: Include verifyingContract (via EIP-712)
88	// The domain separator includes address(this), binding to this specific contract
89	```
90
91	### Type 4: Nonce-Skip Replay
92
93	Nonce implementation allows gaps or out-of-order execution, enabling skipped nonces to be replayed later.
94
95	```solidity
96	// VULNERABLE: Bitmap nonce without invalidation
97	mapping(uint256 => bool) public usedNonces;
98
99	function execute(uint256 nonce, ...) external {
100	require(!usedNonces[nonce], "Used");
101	usedNonces[nonce] = true;
102	// If nonces 1, 2, 3 are used but 4 is skipped,
103	// nonce 4 can be used anytime in the future
104	// This may be intentional OR a vulnerability depending on context
105	}
106
107	// SAFER for strict ordering: Sequential nonce
108	mapping(address => uint256) public nonces;
109
110	function execute(uint256 nonce, ...) external {
111	require(nonce == nonces[signer], "Invalid nonce");
112	nonces[signer]++;
113	}
114	```
115
116	### Type 5: Expired-Signature Replay
117
118	A signature without a deadline can be held and executed at an arbitrary future time when conditions have changed.
119
120	```solidity
121	// VULNERABLE: No deadl

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signature-replay-analysis

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View on GitHub

How to install signature-replay-analysis?

quillai-network/quillshield_skills/signature-replay-analysis

$npx -y skills add quillai-network/quillshield_skills --skill signature-replay-analysis

Installs into the current project.

Summary

Files · 1

View on GitHub

SKILL.md

1	# Signature & Replay Analysis
2
3	Detect vulnerabilities where cryptographic signatures can be reused, replayed across chains/contracts, or exploited through implementation flaws. Research shows 19.63% of Ethereum contracts using signatures contain replay vulnerabilities.
4
5	## When to Use
6
7	- Auditing contracts that verify signatures (`ecrecover`, ECDSA, EIP-712)
8	- Reviewing ERC-20 `permit()` / Uniswap Permit2 implementations
9	- Analyzing meta-transaction / gasless relay systems
10	- Verifying multi-sig signature aggregation
11	- Checking off-chain order books or signed message execution
12
13	## When NOT to Use
14
15	- Contracts without any signature verification
16	- Pure on-chain access control (use semantic-guard-analysis)
17	- Token standard compliance (use external-call-safety)
18
19	## Core Concept: The Signature Trust Model
20
21	A signature proves that a specific private key holder authorized a specific action. For this to be secure, the signature must be:
22
23	1. Bound to context — specific chain, contract, and version (domain separation)
24	2. Used exactly once — nonce prevents replay
25	3. Time-limited — deadline/expiry prevents late execution
26	4. Correctly verified — ecrecover edge cases handled
27
28	Any gap in this model creates a replay vulnerability.
29
30	## The Five Replay Types
31
32	### Type 1: Same-Chain Replay
33
34	The exact same signature is submitted multiple times to the same contract on the same chain.
35
36	```solidity
37	// VULNERABLE: No nonce — same signature works forever
38	function executeWithSig(address to, uint256 amount, bytes memory signature) external {
39	bytes32 hash = keccak256(abi.encodePacked(to, amount));
40	address signer = ECDSA.recover(hash, signature);
41	require(signer == admin, "Invalid signer");
42	token.transfer(to, amount);
43	// Attacker can submit this same signature again and again!
44	}
45
46	// SAFE: Use nonce
47	mapping(address => uint256) public nonces;
48
49	function executeWithSig(address to, uint256 amount, uint256 nonce, bytes memory signature) external {
50	require(nonce == nonces[admin], "Invalid nonce");
51	bytes32 hash = keccak256(abi.encodePacked(to, amount, nonce));
52	address signer = ECDSA.recover(hash, signature);
53	require(signer == admin, "Invalid signer");
54	nonces[admin]++;
55	token.transfer(to, amount);
56	}
57	```
58
59	### Type 2: Cross-Chain Replay
60
61	A signature valid on one chain (e.g., Ethereum) is replayed on another chain (e.g., Polygon, Arbitrum) where the same contract is deployed.
62
63	```solidity
64	// VULNERABLE: No chainId in signed message
65	bytes32 hash = keccak256(abi.encodePacked(to, amount, nonce));
66	// This hash is identical on Ethereum, Polygon, Arbitrum, etc.
67
68	// SAFE: Include chainId (via EIP-712 domain separator)
69	bytes32 DOMAIN_SEPARATOR = keccak256(abi.encode(
70	keccak256("EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)"),
71	keccak256(bytes("MyContract")),
72	keccak256(bytes("1")),
73	block.chainid,
74	address(this)
75	));
76	```
77
78	### Type 3: Cross-Contract Replay
79
80	A signature for Contract A is replayed on Contract B (same chain) if both accept the same message format without contract-specific binding.
81
82	```solidity
83	// VULNERABLE: No contract address in signed message
84	bytes32 hash = keccak256(abi.encodePacked(to, amount, nonce, block.chainid));
85	// Same hash for any contract on this chain
86
87	// SAFE: Include verifyingContract (via EIP-712)
88	// The domain separator includes address(this), binding to this specific contract
89	```
90
91	### Type 4: Nonce-Skip Replay
92
93	Nonce implementation allows gaps or out-of-order execution, enabling skipped nonces to be replayed later.
94
95	```solidity
96	// VULNERABLE: Bitmap nonce without invalidation
97	mapping(uint256 => bool) public usedNonces;
98
99	function execute(uint256 nonce, ...) external {
100	require(!usedNonces[nonce], "Used");
101	usedNonces[nonce] = true;
102	// If nonces 1, 2, 3 are used but 4 is skipped,
103	// nonce 4 can be used anytime in the future
104	// This may be intentional OR a vulnerability depending on context
105	}
106
107	// SAFER for strict ordering: Sequential nonce
108	mapping(address => uint256) public nonces;
109
110	function execute(uint256 nonce, ...) external {
111	require(nonce == nonces[signer], "Invalid nonce");
112	nonces[signer]++;
113	}
114	```
115
116	### Type 5: Expired-Signature Replay
117
118	A signature without a deadline can be held and executed at an arbitrary future time when conditions have changed.
119
120	```solidity
121	// VULNERABLE: No deadl

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