It’s a simple question, but I couldn’t find an answer. In an ERC20 contract lies this code
//The nonce for avoid transfer replay attacks mapping(address => uint256) nonces;
uint256 nonce = nonces[_address_from]; bytes32 h = keccak256(_address_from ,_address_to ,_token_amount, _amount_fee ,nonce); if(_address_from != ecrecover(h,_v,_r,_s)) revert();
_v are functions parameters which must be set manually when calling it on contract execution.
How do I compute
_v from my address and amounts in order to not get the transaction rejected ?