Since I don't use bitcoin, let me ask, does everyone have to download the whole blockchain to their computer in order to mine or receive/sent the coins? Wouldn't the blockchain be in XX GB size by now?
Unfortunately, it appears that AV software completely ignores files larger than 32 MBytes, so it won't notice them in the blockchain— just the chainstate. And so the grand idea of putting the triggers in coinbases didn't work there.
The other fun thing is that the EICAR test trigger is too long to easily stuff in a transaction. Unfortunately there are other "signatures" which are as short as 16 bytes.
In order to have a wallet and just use bitcoin no the user does not need to download the whole blockchain depending on the wallet software. There are wallets that use public shared remote servers to access the blockchain that are reputable in the community.
https://darkwallet.unsystem.net/ (don't use yet, alpha)