Cryptography
| This document is better viewed at https://docs.openzeppelin.com/contracts/api/utils#cryptography |
A collection of contracts and libraries that implement various signature validation schemes and cryptographic primitives. These utilities enable secure authentication, multisignature operations, and advanced cryptographic operations in smart contracts.
-
ECDSA,MessageHashUtils: Libraries for interacting with ECDSA signatures. -
P256: Library for verifying and recovering public keys from secp256r1 signatures. -
RSA: Library with RSA PKCS#1 v1.5 signature verification utilities. -
SignatureChecker: A library helper to support regular ECDSA from EOAs as well as ERC-1271 signatures for smart contracts. -
Hashes: Commonly used hash functions. -
MerkleProof: Functions for verifying Merkle Tree proofs. -
TrieProof: Library for verifying Ethereum Merkle-Patricia trie inclusion proofs. -
EIP712: Contract with functions to allow processing signed typed structure data according to EIP-712. -
ERC7739Utils: Utilities library that implements a defensive rehashing mechanism to prevent replayability of smart contract signatures based on ERC-7739. -
WebAuthn: Library for verifying WebAuthn Authentication Assertions. -
AbstractSigner: Abstract contract for internal signature validation in smart contracts. -
ERC7739: An abstract contract to validate signatures following the rehashing scheme fromERC7739Utils. -
SignerECDSA,SignerP256,SignerRSA: Implementations of anAbstractSignerwith specific signature validation algorithms. -
SignerEIP7702: Implementation ofAbstractSignerthat validates signatures using the contract’s own address as the signer, useful for delegated accounts following EIP-7702. -
SignerWebAuthn: Implementation ofSignerP256that supports WebAuthn -
SignerERC7913,MultiSignerERC7913,MultiSignerERC7913Weighted: Implementations ofAbstractSignerthat validate signatures based on ERC-7913. Including a simple and weighted multisignature scheme. -
ERC7913P256Verifier,ERC7913RSAVerifier,ERC7913WebAuthnVerifier: Ready to use ERC-7913 signature verifiers for P256, RSA keys and WebAuthn.
Utils
ECDSA
import "@openzeppelin/contracts/utils/cryptography/ECDSA.sol";
Elliptic Curve Digital Signature Algorithm (ECDSA) operations.
These functions can be used to verify that a message was signed by the holder of the private keys of a given address.
tryRecover(bytes32 hash, bytes signature) → address recovered, enum ECDSA.RecoverError err, bytes32 errArg internal
Returns the address that signed a hashed message (hash) with signature or an error. This will not
return address(0) without also returning an error description. Errors are documented using an enum (error type)
and a bytes32 providing additional information about the error.
If no error is returned, then the address can be used for verification purposes.
The ecrecover EVM precompile allows for malleable (non-unique) signatures:
this function rejects them by requiring the s value to be in the lower
half order, and the v value to be either 27 or 28.
| This function only supports 65-byte signatures. ERC-2098 short signatures are rejected. This restriction is DEPRECATED and will be removed in v6.0. Developers SHOULD NOT use signatures as unique identifiers; use hash invalidation or nonces for replay protection. |
hash must be the result of a hash operation for the
verification to be secure: it is possible to craft signatures that
recover to arbitrary addresses for non-hashed data. A safe way to ensure
this is by receiving a hash of the original message (which may otherwise
be too long), and then calling MessageHashUtils.toEthSignedMessageHash on it.
|
Documentation for signature generation:
tryRecoverCalldata(bytes32 hash, bytes signature) → address recovered, enum ECDSA.RecoverError err, bytes32 errArg internal
Variant of tryRecover that takes a signature in calldata
recover(bytes32 hash, bytes signature) → address internal
Returns the address that signed a hashed message (hash) with
signature. This address can then be used for verification purposes.
The ecrecover EVM precompile allows for malleable (non-unique) signatures:
this function rejects them by requiring the s value to be in the lower
half order, and the v value to be either 27 or 28.
| This function only supports 65-byte signatures. ERC-2098 short signatures are rejected. This restriction is DEPRECATED and will be removed in v6.0. Developers SHOULD NOT use signatures as unique identifiers; use hash invalidation or nonces for replay protection. |
hash must be the result of a hash operation for the
verification to be secure: it is possible to craft signatures that
recover to arbitrary addresses for non-hashed data. A safe way to ensure
this is by receiving a hash of the original message (which may otherwise
be too long), and then calling MessageHashUtils.toEthSignedMessageHash on it.
|
recoverCalldata(bytes32 hash, bytes signature) → address internal
Variant of recover that takes a signature in calldata
tryRecover(bytes32 hash, bytes32 r, bytes32 vs) → address recovered, enum ECDSA.RecoverError err, bytes32 errArg internal
Overload of ECDSA.tryRecover that receives the r and vs short-signature fields separately.
recover(bytes32 hash, bytes32 r, bytes32 vs) → address internal
Overload of ECDSA.recover that receives the r and vs short-signature fields separately.
tryRecover(bytes32 hash, uint8 v, bytes32 r, bytes32 s) → address recovered, enum ECDSA.RecoverError err, bytes32 errArg internal
Overload of ECDSA.tryRecover that receives the v,
r and s signature fields separately.
recover(bytes32 hash, uint8 v, bytes32 r, bytes32 s) → address internal
Overload of ECDSA.recover that receives the v,
r and s signature fields separately.
parse(bytes signature) → uint8 v, bytes32 r, bytes32 s internal
Parse a signature into its v, r and s components. Supports 65-byte and 64-byte (ERC-2098)
formats. Returns (0,0,0) for invalid signatures.
For 64-byte signatures, v is automatically normalized to 27 or 28.
For 65-byte signatures, v is returned as-is and MUST already be 27 or 28 for use with ecrecover.
Consider validating the result before use, or use tryRecover/recover which perform full validation.
parseCalldata(bytes signature) → uint8 v, bytes32 r, bytes32 s internal
Variant of parse that takes a signature in calldata
MessageHashUtils
import "@openzeppelin/contracts/utils/cryptography/MessageHashUtils.sol";
Signature message hash utilities for producing digests to be consumed by ECDSA recovery or signing.
The library provides methods for generating a hash of a message that conforms to the ERC-191 and EIP 712 specifications.
toEthSignedMessageHash(bytes32 messageHash) → bytes32 digest internal
Returns the keccak256 digest of an ERC-191 signed data with version
0x45 (personal_sign messages).
The digest is calculated by prefixing a bytes32 messageHash with
"\x19Ethereum Signed Message:\n32" and hashing the result. It corresponds with the
hash signed when using the eth_sign JSON-RPC method.
The messageHash parameter is intended to be the result of hashing a raw message with
keccak256, although any bytes32 value can be safely used because the final digest will
be re-hashed.
|
See ECDSA.recover.
toEthSignedMessageHash(bytes message) → bytes32 internal
Returns the keccak256 digest of an ERC-191 signed data with version
0x45 (personal_sign messages).
The digest is calculated by prefixing an arbitrary message with
"\x19Ethereum Signed Message:\n" + len(message) and hashing the result. It corresponds with the
hash signed when using the eth_sign JSON-RPC method.
See ECDSA.recover.
toDataWithIntendedValidatorHash(address validator, bytes data) → bytes32 internal
Returns the keccak256 digest of an ERC-191 signed data with version
0x00 (data with intended validator).
The digest is calculated by prefixing an arbitrary data with "\x19\x00" and the intended
validator address. Then hashing the result.
See ECDSA.recover.
toDataWithIntendedValidatorHash(address validator, bytes32 messageHash) → bytes32 digest internal
Variant of toDataWithIntendedValidatorHash optimized for cases where data is a bytes32.
toTypedDataHash(bytes32 domainSeparator, bytes32 structHash) → bytes32 digest internal
Returns the keccak256 digest of an EIP-712 typed data (ERC-191 version 0x01).
The digest is calculated from a domainSeparator and a structHash, by prefixing them with
\x19\x01 and hashing the result. It corresponds to the hash signed by the
eth_signTypedData JSON-RPC method as part of EIP-712.
See ECDSA.recover.
toDomainSeparator(bytes1 fields, string name, string version, uint256 chainId, address verifyingContract, bytes32 salt) → bytes32 hash internal
Returns the EIP-712 domain separator constructed from an eip712Domain. See IERC5267.eip712Domain
This function dynamically constructs the domain separator based on which fields are present in the
fields parameter. It contains flags that indicate which domain fields are present:
-
Bit 0 (0x01): name
-
Bit 1 (0x02): version
-
Bit 2 (0x04): chainId
-
Bit 3 (0x08): verifyingContract
-
Bit 4 (0x10): salt
Arguments that correspond to fields which are not present in fields are ignored. For example, if fields is
0x0f (0b01111), then the salt parameter is ignored.
toDomainSeparator(bytes1 fields, bytes32 nameHash, bytes32 versionHash, uint256 chainId, address verifyingContract, bytes32 salt) → bytes32 hash internal
Variant of toDomainSeparator that uses hashed name and version.
toDomainTypeHash(bytes1 fields) → bytes32 hash internal
Builds an EIP-712 domain type hash depending on the fields provided, following ERC-5267
P256
import "@openzeppelin/contracts/utils/cryptography/P256.sol";
Implementation of secp256r1 verification and recovery functions.
The secp256r1 curve (also known as P256) is a NIST standard curve with wide support in modern devices and cryptographic standards. Some notable examples include Apple’s Secure Enclave and Android’s Keystore as well as authentication protocols like FIDO2.
Based on the original implementation of itsobvioustech (GNU General Public License v3.0). Heavily inspired in maxrobot and tdrerup implementations.
Available since v5.1.
verify(bytes32 h, bytes32 r, bytes32 s, bytes32 qx, bytes32 qy) → bool internal
Verifies a secp256r1 signature using the RIP-7212 precompile and falls back to the Solidity implementation if the precompile is not available. This version should work on all chains, but requires the deployment of more bytecode.
verifyNative(bytes32 h, bytes32 r, bytes32 s, bytes32 qx, bytes32 qy) → bool internal
Same as verify, but it will revert if the required precompile is not available.
Make sure any logic (code or precompile) deployed at that address is the expected one, otherwise the returned value may be misinterpreted as a positive boolean.
verifySolidity(bytes32 h, bytes32 r, bytes32 s, bytes32 qx, bytes32 qy) → bool internal
Same as verify, but only the Solidity implementation is used.
recovery(bytes32 h, uint8 v, bytes32 r, bytes32 s) → bytes32 x, bytes32 y internal
Public key recovery
RSA
import "@openzeppelin/contracts/utils/cryptography/RSA.sol";
RSA PKCS#1 v1.5 signature verification implementation according to RFC8017.
This library supports PKCS#1 v1.5 padding to avoid malleability via chosen plaintext attacks in practical implementations. The padding follows the EMSA-PKCS1-v1_5-ENCODE encoding definition as per section 9.2 of the RFC. This padding makes RSA semantically secure for signing messages.
Inspired by Adrià Massanet’s work (GNU General Public License v3.0).
Available since v5.1.
pkcs1Sha256(bytes data, bytes s, bytes e, bytes n) → bool internal
Same as pkcs1Sha256 but using SHA256 to calculate the digest of data.
pkcs1Sha256(bytes32 digest, bytes s, bytes e, bytes n) → bool internal
Verifies a PKCSv1.5 signature given a digest according to the verification method described in section 8.2.2 of RFC8017 with support for explicit or implicit NULL parameters in the DigestInfo (no other optional parameters are supported).
| For security reason, this function requires the signature and modulus to have a length of at least 2048 bits. If you use a smaller key, consider replacing it with a larger, more secure, one. |
| This verification algorithm doesn’t prevent replayability. If called multiple times with the same digest, public key and (valid signature), it will return true every time. Consider including an onchain nonce or unique identifier in the message to prevent replay attacks. |
This verification algorithm supports any exponent. NIST recommends using 65537 (or higher).
That is the default value many libraries use, such as OpenSSL. Developers may choose to reject public keys
using a low exponent out of security concerns.
|
SignatureChecker
import "@openzeppelin/contracts/utils/cryptography/SignatureChecker.sol";
Signature verification helper that can be used instead of ECDSA.recover to seamlessly support:
-
ECDSA signatures from externally owned accounts (EOAs)
-
ERC-1271 signatures from smart contract wallets like Argent and Safe Wallet (previously Gnosis Safe)
-
ERC-7913 signatures from keys that do not have an Ethereum address of their own
isValidSignatureNow(address signer, bytes32 hash, bytes signature) → bool internal
Checks if a signature is valid for a given signer and data hash. If the signer has code, the
signature is validated against it using ERC-1271, otherwise it’s validated using ECDSA.recover.
| Unlike ECDSA signatures, contract signatures are revocable, and the outcome of this function can thus change through time. It could return true at block N and false at block N+1 (or the opposite). |
| For an extended version of this function that supports ERC-7913 signatures, see {isValidSignatureNow-bytes-bytes32-bytes-}. |
isValidSignatureNowCalldata(address signer, bytes32 hash, bytes signature) → bool internal
Variant of isValidSignatureNow that takes a signature in calldata
isValidERC1271SignatureNow(address signer, bytes32 hash, bytes signature) → bool result internal
Checks if a signature is valid for a given signer and data hash. The signature is validated against the signer smart contract using ERC-1271.
| Unlike ECDSA signatures, contract signatures are revocable, and the outcome of this function can thus change through time. It could return true at block N and false at block N+1 (or the opposite). |
isValidERC1271SignatureNowCalldata(address signer, bytes32 hash, bytes signature) → bool result internal
isValidSignatureNow(bytes signer, bytes32 hash, bytes signature) → bool internal
Verifies a signature for a given ERC-7913 signer and hash.
The signer is a bytes object that is the concatenation of an address and optionally a key:
verifier || key. A signer must be at least 20 bytes long.
Verification is done as follows:
-
If
signer.length < 20: verification fails -
If
signer.length == 20: verification is done usingisValidSignatureNow -
Otherwise: verification is done using
IERC7913SignatureVerifier
| Unlike ECDSA signatures, contract signatures are revocable, and the outcome of this function can thus change through time. It could return true at block N and false at block N+1 (or the opposite). |
areValidSignaturesNow(bytes32 hash, bytes[] signers, bytes[] signatures) → bool internal
Verifies multiple ERC-7913 signatures for a given hash using a set of signers.
Returns false if the number of signers and signatures is not the same.
The signers should be ordered by their keccak256 hash to ensure efficient duplication check. Unordered
signers are supported, but the uniqueness check will be more expensive.
| Unlike ECDSA signatures, contract signatures are revocable, and the outcome of this function can thus change through time. It could return true at block N and false at block N+1 (or the opposite). |
Hashes
import "@openzeppelin/contracts/utils/cryptography/Hashes.sol";
Library of standard hash functions.
Available since v5.1.
commutativeKeccak256(bytes32 a, bytes32 b) → bytes32 internal
Commutative Keccak256 hash of a sorted pair of bytes32. Frequently used when working with merkle proofs.
Equivalent to the standardNodeHash in our JavaScript library.
|
MerkleProof
import "@openzeppelin/contracts/utils/cryptography/MerkleProof.sol";
These functions deal with verification of Merkle Tree proofs.
The tree and the proofs can be generated using our JavaScript library. You will find a quickstart guide in the readme.
| You should avoid using leaf values that are 64 bytes long prior to hashing, or use a hash function other than keccak256 for hashing leaves. This is because the concatenation of a sorted pair of internal nodes in the Merkle tree could be reinterpreted as a leaf value. OpenZeppelin’s JavaScript library generates Merkle trees that are safe against this attack out of the box. |
| Consider memory side-effects when using custom hashing functions that access memory in an unsafe way. |
This library supports proof verification for merkle trees built using
custom commutative hashing functions (i.e. H(a, b) == H(b, a)). Proving
leaf inclusion in trees built using non-commutative hashing functions requires
additional logic that is not supported by this library.
|
verify(bytes32[] proof, bytes32 root, bytes32 leaf) → bool internal
Returns true if a leaf can be proved to be a part of a Merkle tree
defined by root. For this, a proof must be provided, containing
sibling hashes on the branch from the leaf to the root of the tree. Each
pair of leaves and each pair of pre-images are assumed to be sorted.
This version handles proofs in memory with the default hashing function.
processProof(bytes32[] proof, bytes32 leaf) → bytes32 internal
Returns the rebuilt hash obtained by traversing a Merkle tree up
from leaf using proof. A proof is valid if and only if the rebuilt
hash matches the root of the tree. When processing the proof, the pairs
of leaves & pre-images are assumed to be sorted.
This version handles proofs in memory with the default hashing function.
verify(bytes32[] proof, bytes32 root, bytes32 leaf, function (bytes32,bytes32) view returns (bytes32) hasher) → bool internal
Returns true if a leaf can be proved to be a part of a Merkle tree
defined by root. For this, a proof must be provided, containing
sibling hashes on the branch from the leaf to the root of the tree. Each
pair of leaves and each pair of pre-images are assumed to be sorted.
This version handles proofs in memory with a custom hashing function.
processProof(bytes32[] proof, bytes32 leaf, function (bytes32,bytes32) view returns (bytes32) hasher) → bytes32 internal
Returns the rebuilt hash obtained by traversing a Merkle tree up
from leaf using proof. A proof is valid if and only if the rebuilt
hash matches the root of the tree. When processing the proof, the pairs
of leaves & pre-images are assumed to be sorted.
This version handles proofs in memory with a custom hashing function.
verifyCalldata(bytes32[] proof, bytes32 root, bytes32 leaf) → bool internal
Returns true if a leaf can be proved to be a part of a Merkle tree
defined by root. For this, a proof must be provided, containing
sibling hashes on the branch from the leaf to the root of the tree. Each
pair of leaves and each pair of pre-images are assumed to be sorted.
This version handles proofs in calldata with the default hashing function.
processProofCalldata(bytes32[] proof, bytes32 leaf) → bytes32 internal
Returns the rebuilt hash obtained by traversing a Merkle tree up
from leaf using proof. A proof is valid if and only if the rebuilt
hash matches the root of the tree. When processing the proof, the pairs
of leaves & pre-images are assumed to be sorted.
This version handles proofs in calldata with the default hashing function.
verifyCalldata(bytes32[] proof, bytes32 root, bytes32 leaf, function (bytes32,bytes32) view returns (bytes32) hasher) → bool internal
Returns true if a leaf can be proved to be a part of a Merkle tree
defined by root. For this, a proof must be provided, containing
sibling hashes on the branch from the leaf to the root of the tree. Each
pair of leaves and each pair of pre-images are assumed to be sorted.
This version handles proofs in calldata with a custom hashing function.
processProofCalldata(bytes32[] proof, bytes32 leaf, function (bytes32,bytes32) view returns (bytes32) hasher) → bytes32 internal
Returns the rebuilt hash obtained by traversing a Merkle tree up
from leaf using proof. A proof is valid if and only if the rebuilt
hash matches the root of the tree. When processing the proof, the pairs
of leaves & pre-images are assumed to be sorted.
This version handles proofs in calldata with a custom hashing function.
multiProofVerify(bytes32[] proof, bool[] proofFlags, bytes32 root, bytes32[] leaves) → bool internal
Returns true if the leaves can be simultaneously proven to be a part of a Merkle tree defined by
root, according to proof and proofFlags as described in processMultiProof.
This version handles multiproofs in memory with the default hashing function.
Not all Merkle trees admit multiproofs. See processMultiProof for details.
|
Consider the case where root == proof[0] && leaves.length == 0 as it will return true.
The leaves must be validated independently. See processMultiProof.
|
processMultiProof(bytes32[] proof, bool[] proofFlags, bytes32[] leaves) → bytes32 merkleRoot internal
Returns the root of a tree reconstructed from leaves and sibling nodes in proof. The reconstruction
proceeds by incrementally reconstructing all inner nodes by combining a leaf/inner node with either another
leaf/inner node or a proof sibling node, depending on whether each proofFlags item is true or false
respectively.
This version handles multiproofs in memory with the default hashing function.
| Not all Merkle trees admit multiproofs. To use multiproofs, it is sufficient to ensure that: 1) the tree is complete (but not necessarily perfect), 2) the leaves to be proven are in the opposite order they are in the tree (i.e., as seen from right to left starting at the deepest layer and continuing at the next layer). |
The empty set (i.e. the case where proof.length == 1 && leaves.length == 0) is considered a no-op,
and therefore a valid multiproof (i.e. it returns proof[0]). Consider disallowing this case if you’re not
validating the leaves elsewhere.
|
multiProofVerify(bytes32[] proof, bool[] proofFlags, bytes32 root, bytes32[] leaves, function (bytes32,bytes32) view returns (bytes32) hasher) → bool internal
Returns true if the leaves can be simultaneously proven to be a part of a Merkle tree defined by
root, according to proof and proofFlags as described in processMultiProof.
This version handles multiproofs in memory with a custom hashing function.
Not all Merkle trees admit multiproofs. See processMultiProof for details.
|
Consider the case where root == proof[0] && leaves.length == 0 as it will return true.
The leaves must be validated independently. See processMultiProof.
|
processMultiProof(bytes32[] proof, bool[] proofFlags, bytes32[] leaves, function (bytes32,bytes32) view returns (bytes32) hasher) → bytes32 merkleRoot internal
Returns the root of a tree reconstructed from leaves and sibling nodes in proof. The reconstruction
proceeds by incrementally reconstructing all inner nodes by combining a leaf/inner node with either another
leaf/inner node or a proof sibling node, depending on whether each proofFlags item is true or false
respectively.
This version handles multiproofs in memory with a custom hashing function.
| Not all Merkle trees admit multiproofs. To use multiproofs, it is sufficient to ensure that: 1) the tree is complete (but not necessarily perfect), 2) the leaves to be proven are in the opposite order they are in the tree (i.e., as seen from right to left starting at the deepest layer and continuing at the next layer). |
The empty set (i.e. the case where proof.length == 1 && leaves.length == 0) is considered a no-op,
and therefore a valid multiproof (i.e. it returns proof[0]). Consider disallowing this case if you’re not
validating the leaves elsewhere.
|
multiProofVerifyCalldata(bytes32[] proof, bool[] proofFlags, bytes32 root, bytes32[] leaves) → bool internal
Returns true if the leaves can be simultaneously proven to be a part of a Merkle tree defined by
root, according to proof and proofFlags as described in processMultiProof.
This version handles multiproofs in calldata with the default hashing function.
Not all Merkle trees admit multiproofs. See processMultiProof for details.
|
Consider the case where root == proof[0] && leaves.length == 0 as it will return true.
The leaves must be validated independently. See processMultiProofCalldata.
|
processMultiProofCalldata(bytes32[] proof, bool[] proofFlags, bytes32[] leaves) → bytes32 merkleRoot internal
Returns the root of a tree reconstructed from leaves and sibling nodes in proof. The reconstruction
proceeds by incrementally reconstructing all inner nodes by combining a leaf/inner node with either another
leaf/inner node or a proof sibling node, depending on whether each proofFlags item is true or false
respectively.
This version handles multiproofs in calldata with the default hashing function.
| Not all Merkle trees admit multiproofs. To use multiproofs, it is sufficient to ensure that: 1) the tree is complete (but not necessarily perfect), 2) the leaves to be proven are in the opposite order they are in the tree (i.e., as seen from right to left starting at the deepest layer and continuing at the next layer). |
The empty set (i.e. the case where proof.length == 1 && leaves.length == 0) is considered a no-op,
and therefore a valid multiproof (i.e. it returns proof[0]). Consider disallowing this case if you’re not
validating the leaves elsewhere.
|
multiProofVerifyCalldata(bytes32[] proof, bool[] proofFlags, bytes32 root, bytes32[] leaves, function (bytes32,bytes32) view returns (bytes32) hasher) → bool internal
Returns true if the leaves can be simultaneously proven to be a part of a Merkle tree defined by
root, according to proof and proofFlags as described in processMultiProof.
This version handles multiproofs in calldata with a custom hashing function.
Not all Merkle trees admit multiproofs. See processMultiProof for details.
|
Consider the case where root == proof[0] && leaves.length == 0 as it will return true.
The leaves must be validated independently. See processMultiProofCalldata.
|
processMultiProofCalldata(bytes32[] proof, bool[] proofFlags, bytes32[] leaves, function (bytes32,bytes32) view returns (bytes32) hasher) → bytes32 merkleRoot internal
Returns the root of a tree reconstructed from leaves and sibling nodes in proof. The reconstruction
proceeds by incrementally reconstructing all inner nodes by combining a leaf/inner node with either another
leaf/inner node or a proof sibling node, depending on whether each proofFlags item is true or false
respectively.
This version handles multiproofs in calldata with a custom hashing function.
| Not all Merkle trees admit multiproofs. To use multiproofs, it is sufficient to ensure that: 1) the tree is complete (but not necessarily perfect), 2) the leaves to be proven are in the opposite order they are in the tree (i.e., as seen from right to left starting at the deepest layer and continuing at the next layer). |
The empty set (i.e. the case where proof.length == 1 && leaves.length == 0) is considered a no-op,
and therefore a valid multiproof (i.e. it returns proof[0]). Consider disallowing this case if you’re not
validating the leaves elsewhere.
|
TrieProof
import "@openzeppelin/contracts/utils/cryptography/TrieProof.sol";
Library for verifying Ethereum Merkle-Patricia trie inclusion proofs.
-
Transaction against the transactionsRoot of a block.
-
Event against receiptsRoot of a block.
-
Account details (RLP encoding of [nonce, balance, storageRoot, codeHash]) against the stateRoot of a block.
-
Storage slot (RLP encoding of the value) against the storageRoot of a account.
Proving a storage slot is usually done in 3 steps:
-
From the stateRoot of a block, process the account proof (see
eth_getProof) to get the account details. -
RLP decode the account details to extract the storageRoot.
-
Use storageRoot of that account to process the storageProof (again, see
eth_getProof).
Based on this implementation from optimism.
verify(bytes value, bytes32 root, bytes key, bytes[] proof) → bool internal
Verifies a proof against a given key, value, and root hash.
traverse(bytes32 root, bytes key, bytes[] proof) → bytes internal
Traverses a proof with a given key and returns the value.
Reverts with TrieProofTraversalError if proof is invalid.
tryTraverse(bytes32 root, bytes key, bytes[] proof) → bytes value, enum TrieProof.ProofError err internal
Traverses a proof with a given key and returns the value and an error flag instead of reverting if the proof is invalid. This function may still revert if malformed input leads to RLP decoding errors.
EIP712
import "@openzeppelin/contracts/utils/cryptography/EIP712.sol";
EIP-712 is a standard for hashing and signing of typed structured data.
The encoding scheme specified in the EIP requires a domain separator and a hash of the typed structured data, whose
encoding is very generic and therefore its implementation in Solidity is not feasible, thus this contract
does not implement the encoding itself. Protocols need to implement the type-specific encoding they need in order to
produce the hash of their typed data using a combination of abi.encode and keccak256.
This contract implements the EIP-712 domain separator (_domainSeparatorV4) that is used as part of the encoding
scheme, and the final step of the encoding to obtain the message digest that is then signed via ECDSA
(_hashTypedDataV4).
The implementation of the domain separator was designed to be as efficient as possible while still properly updating the chain id to protect against replay attacks on an eventual fork of the chain.
This contract implements the version of the encoding known as "v4", as implemented by the JSON RPC method
eth_signTypedDataV4 in MetaMask.
|
In the upgradeable version of this contract, the cached values will correspond to the address, and the domain
separator of the implementation contract. This will cause the _domainSeparatorV4 function to always rebuild the
separator from the immutable values, which is cheaper than accessing a cached version in cold storage.
|
constructor(string name, string version) internal
Initializes the domain separator and parameter caches.
The meaning of name and version is specified in
EIP-712:
-
name: the user readable name of the signing domain, i.e. the name of the DApp or the protocol. -
version: the current major version of the signing domain.
| These parameters cannot be changed except through a smart contract upgrade. |
_hashTypedDataV4(bytes32 structHash) → bytes32 internal
Given an already hashed struct, this function returns the hash of the fully encoded EIP712 message for this domain.
This hash can be used together with ECDSA.recover to obtain the signer of a message. For example:
bytes32 digest = _hashTypedDataV4(keccak256(abi.encode(
keccak256("Mail(address to,string contents)"),
mailTo,
keccak256(bytes(mailContents))
)));
address signer = ECDSA.recover(digest, signature);
eip712Domain() → bytes1 fields, string name, string version, uint256 chainId, address verifyingContract, bytes32 salt, uint256[] extensions public
returns the fields and values that describe the domain separator used by this contract for EIP-712 signature.
ERC7739Utils
import "@openzeppelin/contracts/utils/cryptography/draft-ERC7739Utils.sol";
Utilities to process ERC-7739 typed data signatures that are specific to an EIP-712 domain.
This library provides methods to wrap, unwrap and operate over typed data signatures with a defensive rehashing mechanism that includes the app’s EIP-712 and preserves readability of the signed content using an EIP-712 nested approach.
A smart contract domain can validate a signature for a typed data structure in two ways:
-
As an application validating a typed data signature. See
typedDataSignStructHash. -
As a smart contract validating a raw message signature. See
personalSignStructHash.
A provider for a smart contract wallet would need to return this signature as the
result of a call to personal_sign or eth_signTypedData, and this may be unsupported by
API clients that expect a return value of 129 bytes, or specifically the r,s,v parameters
of an ECDSA signature, as is for example specified for
EIP-712.
|
encodeTypedDataSig(bytes signature, bytes32 appSeparator, bytes32 contentsHash, string contentsDescr) → bytes internal
Nest a signature for a given EIP-712 type into a nested signature for the domain of the app.
Counterpart of decodeTypedDataSig to extract the original signature and the nested components.
decodeTypedDataSig(bytes encodedSignature) → bytes signature, bytes32 appSeparator, bytes32 contentsHash, string contentsDescr internal
Parses a nested signature into its components.
Constructed as follows:
signature ‖ APP_DOMAIN_SEPARATOR ‖ contentsHash ‖ contentsDescr ‖ uint16(contentsDescr.length)
-
signatureis the signature for the (ERC-7739) nested struct hash. This signature indirectly signs over the original "contents" hash (from the app) and the account’s domain separator. -
APP_DOMAIN_SEPARATORis the EIP-712EIP712._domainSeparatorV4of the application smart contract that is requesting the signature verification (through ERC-1271). -
contentsHashis the hash of the underlying data structure or message. -
contentsDescris a descriptor of the "contents" part of the EIP-712 type of the nested signature.
| This function returns empty if the input format is invalid instead of reverting. |
personalSignStructHash(bytes32 contents) → bytes32 internal
Nests an ERC-191 digest into a PersonalSign EIP-712 struct, and returns the corresponding struct hash.
This struct hash must be combined with a domain separator, using MessageHashUtils.toTypedDataHash before
being verified/recovered.
This is used to simulate the personal_sign RPC method in the context of smart contracts.
typedDataSignStructHash(string contentsName, string contentsType, bytes32 contentsHash, bytes domainBytes) → bytes32 result internal
Nests an EIP-712 hash (contents) into a TypedDataSign EIP-712 struct, and returns the corresponding
struct hash. This struct hash must be combined with a domain separator, using MessageHashUtils.toTypedDataHash
before being verified/recovered.
typedDataSignStructHash(string contentsDescr, bytes32 contentsHash, bytes domainBytes) → bytes32 result internal
Variant of typedDataSignStructHash that takes a content descriptor
and decodes the contentsName and contentsType out of it.
typedDataSignTypehash(string contentsName, string contentsType) → bytes32 internal
Compute the EIP-712 typehash of the TypedDataSign structure for a given type (and typename).
decodeContentsDescr(string contentsDescr) → string contentsName, string contentsType internal
Parse the type name out of the ERC-7739 contents type description. Supports both the implicit and explicit modes.
Following ERC-7739 specifications, a contentsName is considered invalid if it’s empty or it contains
any of the following bytes , )\x00
If the contentsType is invalid, this returns an empty string. Otherwise, the return string has non-zero
length.
WebAuthn
import "@openzeppelin/contracts/utils/cryptography/WebAuthn.sol";
Library for verifying WebAuthn Authentication Assertions.
WebAuthn enables strong authentication for smart contracts using P256 as an alternative to traditional secp256k1 ECDSA signatures. This library verifies signatures generated during WebAuthn authentication ceremonies as specified in the WebAuthn Level 2 standard.
For blockchain use cases, the following WebAuthn validations are intentionally omitted:
-
Origin validation: Origin verification in
clientDataJSONis omitted as blockchain contexts rely on authenticator and dapp frontend enforcement. Standard authenticators implement proper origin validation. -
RP ID hash validation: Verification of
rpIdHashin authenticatorData against expected RP ID hash is omitted. This is typically handled by platform-level security measures. Including an expiry timestamp in signed data is recommended for enhanced security. -
Signature counter: Verification of signature counter increments is omitted. While useful for detecting credential cloning, on-chain operations typically include nonce protection, making this check redundant.
-
Extension outputs: Extension output value verification is omitted as these are not essential for core authentication security in blockchain applications.
-
Attestation: Attestation object verification is omitted as this implementation focuses on authentication (
webauthn.get) rather than registration ceremonies.
Inspired by:
verify(bytes challenge, struct WebAuthn.WebAuthnAuth auth, bytes32 qx, bytes32 qy) → bool internal
Performs standard verification of a WebAuthn Authentication Assertion.
verify(bytes challenge, struct WebAuthn.WebAuthnAuth auth, bytes32 qx, bytes32 qy, bool requireUV) → bool internal
Performs verification of a WebAuthn Authentication Assertion. This variants allow the caller to select whether of not to require the UV flag (step 17).
Verifies:
-
Type is "webauthn.get" (see {_validateExpectedTypeHash})
-
Challenge matches the expected value (see {_validateChallenge})
-
Cryptographic signature is valid for the given public key
-
confirming physical user presence during authentication
-
(if
requireUVis true) confirming stronger user authentication (biometrics/PIN) -
Backup Eligibility (
BE) and Backup State (BS) bits relationship is valid
tryDecodeAuth(bytes input) → bool success, struct WebAuthn.WebAuthnAuth auth internal
Verifies that calldata bytes (input) represents a valid WebAuthnAuth object. If encoding is valid,
returns true and the calldata view at the object. Otherwise, returns false and an invalid calldata object.
The returned auth object should not be accessed if success is false. Trying to access the data may
cause revert/panic.
|
bytes1 AUTH_DATA_FLAGS_UP internal constant
Bit 0 of the authenticator data flags: "User Present" bit.
bytes1 AUTH_DATA_FLAGS_UV internal constant
Bit 2 of the authenticator data flags: "User Verified" bit.
Abstract Signers
AbstractSigner
import "@openzeppelin/contracts/utils/cryptography/signers/AbstractSigner.sol";
Abstract contract for signature validation.
Developers must implement _rawSignatureValidation and use it as the lowest-level signature validation mechanism.
@custom:stateless
ERC7739
import "@openzeppelin/contracts/utils/cryptography/signers/draft-ERC7739.sol";
Validates signatures wrapping the message hash in a nested EIP712 type. See ERC7739Utils.
Linking the signature to the EIP-712 domain separator is a security measure to prevent signature replay across different EIP-712 domains (e.g. a single offchain owner of multiple contracts).
This contract requires implementing the _rawSignatureValidation function, which passes the wrapped message hash,
which may be either an typed data or a personal sign nested type.
| EIP-712 uses ShortStrings to optimize gas costs for short strings (up to 31 characters). Consider that strings longer than that will use storage, which may limit the ability of the signer to be used within the ERC-4337 validation phase (due to ERC-7562 storage access rules). |
isValidSignature(bytes32 hash, bytes signature) → bytes4 result public
Attempts validating the signature in a nested EIP-712 type.
A nested EIP-712 type might be presented in 2 different ways:
-
As a nested EIP-712 typed data
-
As a personal signature (an EIP-712 mimic of the
eth_personalSignfor a smart contract)
SignerECDSA
import "@openzeppelin/contracts/utils/cryptography/signers/SignerECDSA.sol";
Implementation of AbstractSigner using ECDSA signatures.
For Account usage, a _setSigner function is provided to set the signer address.
Doing so is easier for a factory, who is likely to use initializable clones of this contract.
Example of usage:
contract MyAccountECDSA is Account, SignerECDSA, Initializable {
function initialize(address signerAddr) public initializer {
_setSigner(signerAddr);
}
}
Failing to call _setSigner either during construction (if used standalone)
or during initialization (if used as a clone) may leave the signer either front-runnable or unusable.
|
_setSigner(address signerAddr) internal
Sets the signer with the address of the native signer. This function should be called during construction or through an initializer.
SignerP256
import "@openzeppelin/contracts/utils/cryptography/signers/SignerP256.sol";
Implementation of AbstractSigner using P256 signatures.
For Account usage, a _setSigner function is provided to set the signer public key.
Doing so is easier for a factory, who is likely to use initializable clones of this contract.
Example of usage:
contract MyAccountP256 is Account, SignerP256, Initializable {
function initialize(bytes32 qx, bytes32 qy) public initializer {
_setSigner(qx, qy);
}
}
Failing to call _setSigner either during construction (if used standalone)
or during initialization (if used as a clone) may leave the signer either front-runnable or unusable.
|
_setSigner(bytes32 qx, bytes32 qy) internal
Sets the signer with a P256 public key. This function should be called during construction or through an initializer.
SignerRSA
import "@openzeppelin/contracts/utils/cryptography/signers/SignerRSA.sol";
Implementation of AbstractSigner using RSA signatures.
For Account usage, a _setSigner function is provided to set the signer public key.
Doing so is easier for a factory, who is likely to use initializable clones of this contract.
Example of usage:
contract MyAccountRSA is Account, SignerRSA, Initializable {
function initialize(bytes memory e, bytes memory n) public initializer {
_setSigner(e, n);
}
}
Failing to call _setSigner either during construction (if used standalone)
or during initialization (if used as a clone) may leave the signer either front-runnable or unusable.
|
_setSigner(bytes e, bytes n) internal
Sets the signer with a RSA public key. This function should be called during construction or through an initializer.
_rawSignatureValidation(bytes32 hash, bytes signature) → bool internal
See AbstractSigner._rawSignatureValidation. Verifies a PKCSv1.5 signature by calling
RSA.pkcs1Sha256.
Following the RSASSA-PKCS1-V1_5-VERIFY procedure outlined in RFC8017 (section 8.2.2), the
provided hash is used as the M (message) and rehashed using SHA256 according to EMSA-PKCS1-v1_5
encoding as per section 9.2 (step 1) of the RFC.
|
SignerEIP7702
import "@openzeppelin/contracts/utils/cryptography/signers/SignerEIP7702.sol";
Implementation of AbstractSigner for implementation for an EOA. Useful for EIP-7702 accounts.
@custom:stateless
SignerERC7913
import "@openzeppelin/contracts/utils/cryptography/signers/SignerERC7913.sol";
Implementation of AbstractSigner using
ERC-7913 signature verification.
For Account usage, a _setSigner function is provided to set the ERC-7913 formatted signer.
Doing so is easier for a factory, who is likely to use initializable clones of this contract.
The signer is a bytes object that concatenates a verifier address and a key: verifier || key.
Example of usage:
contract MyAccountERC7913 is Account, SignerERC7913, Initializable {
function initialize(bytes memory signer_) public initializer {
_setSigner(signer_);
}
function setSigner(bytes memory signer_) public onlyEntryPointOrSelf {
_setSigner(signer_);
}
}
Failing to call _setSigner either during construction (if used standalone)
or during initialization (if used as a clone) may leave the signer either front-runnable or unusable.
|
_setSigner(bytes signer_) internal
Sets the signer (i.e. verifier || key) with an ERC-7913 formatted signer.
_rawSignatureValidation(bytes32 hash, bytes signature) → bool internal
Verifies a signature using {SignatureChecker-isValidSignatureNow-bytes-bytes32-bytes-}
with signer, hash and signature.
MultiSignerERC7913
import "@openzeppelin/contracts/utils/cryptography/signers/MultiSignerERC7913.sol";
Implementation of AbstractSigner using multiple ERC-7913 signers with a threshold-based
signature verification system.
This contract allows managing a set of authorized signers and requires a minimum number of signatures (threshold) to approve operations. It uses ERC-7913 formatted signers, which makes it natively compatible with ECDSA and ERC-1271 signers.
Example of usage:
contract MyMultiSignerAccount is Account, MultiSignerERC7913, Initializable {
function initialize(bytes[] memory signers, uint64 threshold) public initializer {
_addSigners(signers);
_setThreshold(threshold);
}
function addSigners(bytes[] memory signers) public onlyEntryPointOrSelf {
_addSigners(signers);
}
function removeSigners(bytes[] memory signers) public onlyEntryPointOrSelf {
_removeSigners(signers);
}
function setThreshold(uint64 threshold) public onlyEntryPointOrSelf {
_setThreshold(threshold);
}
}
| Failing to properly initialize the signers and threshold either during construction (if used standalone) or during initialization (if used as a clone) may leave the contract either front-runnable or unusable. |
getSigners(uint64 start, uint64 end) → bytes[] public
Returns a slice of the set of authorized signers.
Using start = 0 and end = type(uint64).max will return the entire set of signers.
Depending on the start and end, this operation can copy a large amount of data to memory, which
can be expensive. This is designed for view accessors queried without gas fees. Using it in state-changing
functions may become uncallable if the slice grows too large.
|
threshold() → uint64 public
Returns the minimum number of signers required to approve a multisignature operation.
_addSigners(bytes[] newSigners) internal
Adds the newSigners to those allowed to sign on behalf of this contract.
Internal version without access control.
Requirements:
-
Each of
newSignersmust be at least 20 bytes long. Reverts withMultiSignerERC7913InvalidSignerif not. -
Each of
newSignersmust not be authorized. SeeisSigner. Reverts withMultiSignerERC7913AlreadyExistsif so.
_removeSigners(bytes[] oldSigners) internal
Removes the oldSigners from the authorized signers. Internal version without access control.
Requirements:
-
Each of
oldSignersmust be authorized. SeeisSigner. OtherwiseMultiSignerERC7913NonexistentSigneris thrown. -
See
_validateReachableThresholdfor the threshold validation.
_setThreshold(uint64 newThreshold) internal
Sets the signatures threshold required to approve a multisignature operation.
Internal version without access control.
Requirements:
-
See
_validateReachableThresholdfor the threshold validation.
_validateReachableThreshold() internal
Validates the current threshold is reachable.
Requirements:
-
The
getSignerCountmust be greater or equal than to thethreshold. ThrowsMultiSignerERC7913UnreachableThresholdif not.
_rawSignatureValidation(bytes32 hash, bytes signature) → bool internal
Decodes, validates the signature and checks the signers are authorized.
See _validateSignatures and _validateThreshold for more details.
Example of signature encoding:
// Encode signers (verifier || key)
bytes memory signer1 = abi.encodePacked(verifier1, key1);
bytes memory signer2 = abi.encodePacked(verifier2, key2);
// Order signers by their id
if (keccak256(signer1) > keccak256(signer2)) {
(signer1, signer2) = (signer2, signer1);
(signature1, signature2) = (signature2, signature1);
}
// Assign ordered signers and signatures
bytes[] memory signers = new bytes[](2);
bytes[] memory signatures = new bytes[](2);
signers[0] = signer1;
signatures[0] = signature1;
signers[1] = signer2;
signatures[1] = signature2;
// Encode the multi signature
bytes memory signature = abi.encode(signers, signatures);
Requirements:
-
The
signaturemust be encoded asabi.encode(signers, signatures).
_validateSignatures(bytes32 hash, bytes[] signers, bytes[] signatures) → bool valid internal
Validates the signatures using the signers and their corresponding signatures. Returns whether the signers are authorized and the signatures are valid for the given hash.
Sorting the signers by their keccak256 hash will improve the gas efficiency of this function.
See {SignatureChecker-areValidSignaturesNow-bytes32-bytes[]-bytes[]} for more details.
|
Requirements:
-
The
signaturesandsignersarrays must be equal in length. Returns false otherwise.
_validateThreshold(bytes[] validatingSigners) → bool internal
Validates that the number of signers meets the threshold requirement.
Assumes the signers were already validated. See _validateSignatures for more details.
MultiSignerERC7913Weighted
import "@openzeppelin/contracts/utils/cryptography/signers/MultiSignerERC7913Weighted.sol";
Extension of MultiSignerERC7913 that supports weighted signatures.
This contract allows assigning different weights to each signer, enabling more flexible governance schemes. For example, some signers could have higher weight than others, allowing for weighted voting or prioritized authorization.
Example of usage:
contract MyWeightedMultiSignerAccount is Account, MultiSignerERC7913Weighted, Initializable {
function initialize(bytes[] memory signers, uint64[] memory weights, uint64 threshold) public initializer {
_addSigners(signers);
_setSignerWeights(signers, weights);
_setThreshold(threshold);
}
function addSigners(bytes[] memory signers) public onlyEntryPointOrSelf {
_addSigners(signers);
}
function removeSigners(bytes[] memory signers) public onlyEntryPointOrSelf {
_removeSigners(signers);
}
function setThreshold(uint64 threshold) public onlyEntryPointOrSelf {
_setThreshold(threshold);
}
function setSignerWeights(bytes[] memory signers, uint64[] memory weights) public onlyEntryPointOrSelf {
_setSignerWeights(signers, weights);
}
}
When setting a threshold value, ensure it matches the scale used for signer weights.
For example, if signers have weights like 1, 2, or 3, then a threshold of 4 would require at
least two signers (e.g., one with weight 1 and one with weight 3). See signerWeight.
|
signerWeight(bytes signer) → uint64 public
Gets the weight of a signer. Returns 0 if the signer is not authorized.
_setSignerWeights(bytes[] signers, uint64[] weights) internal
Sets weights for multiple signers at once. Internal version without access control.
Requirements:
-
signersandweightsarrays must have the same length. Reverts withMultiSignerERC7913WeightedMismatchedLengthon mismatch. -
Each signer must exist in the set of authorized signers. Otherwise reverts with
MultiSignerERC7913NonexistentSigner -
Each weight must be greater than 0. Otherwise reverts with
MultiSignerERC7913WeightedInvalidWeight -
See
_validateReachableThresholdfor the threshold validation.
Emits ERC7913SignerWeightChanged for each signer.
_addSigners(bytes[] newSigners) internal
In cases where totalWeight is almost type(uint64).max (due to a large _totalExtraWeight), adding new
signers could cause the totalWeight computation to overflow. Adding a totalWeight calls after the new
signers are added ensures no such overflow happens.
_removeSigners(bytes[] signers) internal
Just like _addSigners, this function does not emit ERC7913SignerWeightChanged events. The
ERC7913SignerRemoved event emitted by MultiSignerERC7913._removeSigners is enough to track weights here.
_validateReachableThreshold() internal
Sets the threshold for the multisignature operation. Internal version without access control.
Requirements:
-
The
totalWeightmust be>=thethreshold. Otherwise reverts withMultiSignerERC7913UnreachableThreshold
This function intentionally does not call super._validateReachableThreshold because the base implementation
assumes each signer has a weight of 1, which is a subset of this weighted implementation. Consider that multiple
implementations of this function may exist in the contract, so important side effects may be missed
depending on the linearization order.
|
_validateThreshold(bytes[] signers) → bool internal
Validates that the total weight of signers meets the threshold requirement.
This function intentionally does not call super._validateThreshold because the base implementation
assumes each signer has a weight of 1, which is a subset of this weighted implementation. Consider that multiple
implementations of this function may exist in the contract, so important side effects may be missed
depending on the linearization order.
|
ERC7913SignerWeightChanged(bytes indexed signer, uint64 weight) event
Emitted when a signer’s weight is changed.
Not emitted in _addSigners or _removeSigners. Indexers must rely on ERC7913SignerAdded
and ERC7913SignerRemoved to index a default weight of 1. See signerWeight.
|
MultiSignerERC7913WeightedInvalidWeight(bytes signer, uint64 weight) error
Thrown when a signer’s weight is invalid.
MultiSignerERC7913WeightedMismatchedLength() error
Thrown when the arrays lengths don’t match. See _setSignerWeights.
Verifiers
ERC7913P256Verifier
import "@openzeppelin/contracts/utils/cryptography/verifiers/ERC7913P256Verifier.sol";
ERC-7913 signature verifier that support P256 (secp256r1) keys.
@custom:stateless
verify(bytes key, bytes32 hash, bytes signature) → bytes4 public
Verifies signature as a valid signature of hash by key.
MUST return the bytes4 magic value IERC7913SignatureVerifier.verify.selector if the signature is valid. SHOULD return 0xffffffff or revert if the signature is not valid. SHOULD return 0xffffffff or revert if the key is empty
ERC7913RSAVerifier
import "@openzeppelin/contracts/utils/cryptography/verifiers/ERC7913RSAVerifier.sol";
ERC-7913 signature verifier that support RSA keys.
@custom:stateless
verify(bytes key, bytes32 hash, bytes signature) → bytes4 public
Verifies signature as a valid signature of hash by key.
MUST return the bytes4 magic value IERC7913SignatureVerifier.verify.selector if the signature is valid. SHOULD return 0xffffffff or revert if the signature is not valid. SHOULD return 0xffffffff or revert if the key is empty
ERC7913WebAuthnVerifier
import "@openzeppelin/contracts/utils/cryptography/verifiers/ERC7913WebAuthnVerifier.sol";
ERC-7913 signature verifier that supports WebAuthn authentication assertions.
This verifier enables the validation of WebAuthn signatures using P256 public keys.
The key is expected to be a 64-byte concatenation of the P256 public key coordinates (qx || qy).
The signature is expected to be an abi-encoded WebAuthn.WebAuthnAuth struct.
Uses WebAuthn.verify for signature verification, which performs the essential
WebAuthn checks: type validation, challenge matching, and cryptographic signature verification.
| Wallets that may require default P256 validation may install a P256 verifier separately. |
@custom:stateless
verify(bytes key, bytes32 hash, bytes signature) → bytes4 public
Verifies signature as a valid signature of hash by key.
MUST return the bytes4 magic value IERC7913SignatureVerifier.verify.selector if the signature is valid. SHOULD return 0xffffffff or revert if the signature is not valid. SHOULD return 0xffffffff or revert if the key is empty