Nonces for permit signatures. Mapping: (verifying_contract, owner_address) => nonce
Uses Blake2_128Concat for the first key to prevent storage collision attacks when the verifying_contract address could be influenced by an attacker.
Note: EIP-2612 specifies uint256 nonce. We store as U256 for compatibility.
Nonces for permit signatures. Mapping: (verifying_contract, owner_address) => nonce
Uses Blake2_128Concat for the first key to prevent storage collision attacks when the verifying_contract address could be influenced by an attacker.
Note: EIP-2612 specifies uint256 nonce. We store as U256 for compatibility.