Guys how i can call the following permit() function, what

Question

Guys how i can call the following permit() function, what

parameters should i pass for v,r,s? Any help is appreciated!

function permit(
address owner,
address spender,
uint256 value,
uint256 deadline,
uint8 v,
bytes32 r,
bytes32 s
) public virtual override {
require(block.timestamp <= deadline, "ERC20Permit: expired deadline");
bytes32 structHash = keccak256(abi.encode(_PERMIT_TYPEHASH, owner, spender, value, _useNonce(owner), deadline));
bytes32 hash = _hashTypedDataV4(structHash);
address signer = ECDSA.recover(hash, v, r, s);
require(signer == owner, "ERC20Permit: invalid signature");
_approve(owner, spender, value);
}

#english #programming #solidity

0

06.07.2022

11 ответов

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Crypto Find ⚠️ ☢️ Автор вопроса

Also can this be exploited so random user approves the tokens for another user to spend and then transfer them to his account via the transferFrom() function?

0

06.07.2022

EVM Ninja

(v,r,s) are ECDSA components (digital signature)

0

06.07.2022

Crypto Find ⚠️ ☢️ Автор вопроса

Can this be exploited so users gets approval for spend on random addresses and withdraw each others tokens via transferFrom() function, because they will now have the allowances reuqired?

0

06.07.2022

Grim (Travelling)

Without the user signing the permit data using his wallet, no

0

06.07.2022

EVM Ninja

Crypto Find ⚠️ ☢️
Can this be exploited so users gets approval for s...

There are many attack vectors one can use to trick victims. However, the function alone is safe

0

06.07.2022

Crypto Find ⚠️ ☢️ Автор вопроса

Grim (Travelling)
Without the user signing the permit data using his...

can they use the 0x0 address as owner so they 'mint' them tokens from the -x- address?

0

06.07.2022

Crypto Find ⚠️ ☢️ Автор вопроса

So what i understand from this so far is - anyone can request for approval to spend someone's tokens but they cannot access them until the requested party 'approve' their request. Am i getting this right?

0

06.07.2022

Grim (Travelling)

Crypto Find ⚠️ ☢️
So what i understand from this so far is - anyone ...

Think of it as like a real life permit. User A writes the following into a paper "User B is granting access to User A for taking X amount from User B's wallet" This has no validity until User B signs the paper right? That's exactly how erc20permit works too.

0

06.07.2022

Crypto Find ⚠️ ☢️ Автор вопроса

Grim (Travelling)
Think of it as like a real life permit. User A wri...

Thanks, thats good clarification! So this cannot be abused as 'mint' fom 0x0 address and withdrawing ones tokens without interaction from the requested side, yes?

0

06.07.2022

Grim (Travelling)

Crypto Find ⚠️ ☢️
Thanks, thats good clarification! So this cannot b...

Yep just like normal approve-transferFrom pattern, you can't take it without the requested party's consent (sign)

0

06.07.2022

Grim (Travelling) · Accepted Answer

Grim (Travelling)

Its the signature you are going to pass

0

06.07.2022

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Guys how i can call the following permit() function, what

11 ответов

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