Permit2

0xA4Bf80b2CFBd80C00cB0Cc3d74C8762Ff4762770

Permit2 handles signature-based transfers in SignatureTransfer and allowance-based transfers in AllowanceTransfer.

Users must approve Permit2 before calling any of the transfer functions.

State Variables

allowance

Maps users to tokens to spender addresses and information about the approval on the token

Indexed in the order of token owner address, token address, spender address

The stored word saves the allowed amount, expiration on the allowance, and nonce

mapping(address => mapping(address => mapping(address => PackedAllowance))) public allowance;

nonceBitmap

A map from token owner address and a caller specified word index to a bitmap. Used to set bits in the bitmap to prevent against signature replay protection

Uses unordered nonces so that permit messages do not need to be spent in a certain order

mapping(address => mapping(uint256 => uint256)) public nonceBitmap;

Functions

permitTransferFrom

Transfers a token using a signed permit message

Reverts if the requested amount is greater than the permitted signed amount

function permitTransferFrom(
    PermitTransferFrom memory permit,
    SignatureTransferDetails calldata transferDetails,
    address owner,
    bytes calldata signature
) external;

Parameters

Name	Type	Description
permit	PermitTransferFrom	The permit data signed over by the owner
transferDetails	SignatureTransferDetails	The spender's requested transfer details for the permitted token
owner	address	The owner of the tokens to transfer
signature	bytes	The signature to verify

permitWitnessTransferFrom

Transfers a token using a signed permit message

The witness type string must follow EIP712 ordering of nested structs and must include the TokenPermissions type definition

function permitWitnessTransferFrom(
    PermitTransferFrom memory permit,
    SignatureTransferDetails calldata transferDetails,
    address owner,
    bytes32 witness,
    string calldata witnessTypeString,
    bytes calldata signature
) external;

Parameters

Name	Type	Description
permit	PermitTransferFrom	The permit data signed over by the owner
transferDetails	SignatureTransferDetails	The spender's requested transfer details for the permitted token
owner	address	The owner of the tokens to transfer
witness	bytes32	Extra data to include when checking the user signature
witnessTypeString	string	The EIP-712 type definition for remaining string stub of the typehash
signature	bytes	The signature to verify

_permitTransferFrom

Transfers a token using a signed permit message.

function _permitTransferFrom(
    PermitTransferFrom memory permit,
    SignatureTransferDetails calldata transferDetails,
    address owner,
    bytes32 dataHash,
    bytes calldata signature
) private;

Parameters

Name	Type	Description
permit	PermitTransferFrom	The permit data signed over by the owner
transferDetails	SignatureTransferDetails	The spender's requested transfer details for the permitted token
owner	address	The owner of the tokens to transfer
dataHash	bytes32	The EIP-712 hash of permit data to include when checking signature
signature	bytes	The signature to verify

permitTransferFrom

Transfers a token using a signed permit message

Reverts if the requested amount is greater than the permitted signed amount

function permitTransferFrom(
    PermitBatchTransferFrom memory permit,
    SignatureTransferDetails[] calldata transferDetails,
    address owner,
    bytes calldata signature
) external;

Parameters

Name	Type	Description
permit	PermitBatchTransferFrom	The permit data signed over by the owner
transferDetails	SignatureTransferDetails[]	The spender's requested transfer details for the permitted token
owner	address	The owner of the tokens to transfer
signature	bytes	The signature to verify

permitWitnessTransferFrom

Transfers a token using a signed permit message

The witness type string must follow EIP712 ordering of nested structs and must include the TokenPermissions type definition

function permitWitnessTransferFrom(
    PermitBatchTransferFrom memory permit,
    SignatureTransferDetails[] calldata transferDetails,
    address owner,
    bytes32 witness,
    string calldata witnessTypeString,
    bytes calldata signature
) external;

Parameters

Name	Type	Description
permit	PermitBatchTransferFrom	The permit data signed over by the owner
transferDetails	SignatureTransferDetails[]	The spender's requested transfer details for the permitted token
owner	address	The owner of the tokens to transfer
witness	bytes32	Extra data to include when checking the user signature
witnessTypeString	string	The EIP-712 type definition for remaining string stub of the typehash
signature	bytes	The signature to verify

_permitTransferFrom

Transfers tokens using a signed permit messages

function _permitTransferFrom(
    PermitBatchTransferFrom memory permit,
    SignatureTransferDetails[] calldata transferDetails,
    address owner,
    bytes32 dataHash,
    bytes calldata signature
) private;

Parameters

Name	Type	Description
permit	PermitBatchTransferFrom	The permit data signed over by the owner
transferDetails	SignatureTransferDetails[]
owner	address	The owner of the tokens to transfer
dataHash	bytes32	The EIP-712 hash of permit data to include when checking signature
signature	bytes	The signature to verify

invalidateUnorderedNonces

Invalidates the bits specified in mask for the bitmap at the word position

The wordPos is maxed at type(uint248).max

function invalidateUnorderedNonces(uint256 wordPos, uint256 mask) external;

Parameters

Name	Type	Description
wordPos	uint256	A number to index the nonceBitmap at
mask	uint256	A bitmap masked against msg.sender's current bitmap at the word position

bitmapPositions

Returns the index of the bitmap and the bit position within the bitmap. Used for unordered nonces

The first 248 bits of the nonce value is the index of the desired bitmap

The last 8 bits of the nonce value is the position of the bit in the bitmap

function bitmapPositions(uint256 nonce) private pure returns (uint256 wordPos, uint256 bitPos);

Parameters

Name	Type	Description
nonce	uint256	The nonce to get the associated word and bit positions

Returns

Name	Type	Description
wordPos	uint256	The word position or index into the nonceBitmap
bitPos	uint256	The bit position

_useUnorderedNonce

Checks whether a nonce is taken and sets the bit at the bit position in the bitmap at the word position

function _useUnorderedNonce(address from, uint256 nonce) internal;

Parameters

Name	Type	Description
from	address	The address to use the nonce at
nonce	uint256	The nonce to spend

approve

Approves the spender to use up to amount of the specified token up until the expiration

The packed allowance also holds a nonce, which will stay unchanged in approve

function approve(address token, address spender, uint160 amount, uint48 expiration) external;

Parameters

Name	Type	Description
token	address	The token to approve
spender	address	The spender address to approve
amount	uint160	The approved amount of the token
expiration	uint48	The timestamp at which the approval is no longer valid

permit

Permit a spender to a given amount of the owners token via the owner's EIP-712 signature

May fail if the owner's nonce was invalidated in-flight by invalidateNonce

function permit(address owner, PermitSingle memory permitSingle, bytes calldata signature)
    external;

Parameters

Name	Type	Description
owner	address	The owner of the tokens being approved
permitSingle	PermitSingle	Data signed over by the owner specifying the terms of approval
signature	bytes	The owner's signature over the permit data

permit

Permit a spender to a given amount of the owners token via the owner's EIP-712 signature

May fail if the owner's nonce was invalidated in-flight by invalidateNonce

function permit(address owner, PermitBatch memory permitBatch, bytes calldata signature) external;

Parameters

Name	Type	Description
owner	address	The owner of the tokens being approved
permitBatch	PermitBatch
signature	bytes	The owner's signature over the permit data

transferFrom

Transfer approved tokens from one address to another

Requires the from address to have approved at least the desired amount of tokens to msg.sender.

function transferFrom(address from, address to, uint160 amount, address token) external;

Parameters

Name	Type	Description
from	address	The address to transfer from
to	address	The address of the recipient
amount	uint160	The amount of the token to transfer
token	address	The token address to transfer

transferFrom

Transfer approved tokens from one address to another

Requires the from address to have approved at least the desired amount of tokens to msg.sender.

function transferFrom(AllowanceTransferDetails[] calldata transferDetails) external;

Parameters

Name	Type	Description
transferDetails	AllowanceTransferDetails[]

_transfer

Internal function for transferring tokens using stored allowances

Will fail if the allowed timeframe has passed

function _transfer(address from, address to, uint160 amount, address token) private;

lockdown

Enables performing a "lockdown" of the sender's Permit2 identity by batch revoking approvals

function lockdown(TokenSpenderPair[] calldata approvals) external;

Parameters

Name	Type	Description
approvals	TokenSpenderPair[]	Array of approvals to revoke.

invalidateNonces

Invalidate nonces for a given (token, spender) pair

Can't invalidate more than 2**16 nonces per transaction.

function invalidateNonces(address token, address spender, uint48 newNonce) external;

Parameters

Name	Type	Description
token	address	The token to invalidate nonces for
spender	address	The spender to invalidate nonces for
newNonce	uint48	The new nonce to set. Invalidates all nonces less than it.

_updateApproval

Sets the new values for amount, expiration, and nonce.

Will check that the signed nonce is equal to the current nonce and then incrememnt the nonce value by 1.

Emits a Permit event.

function _updateApproval(PermitDetails memory details, address owner, address spender) private;