The network layer authenticates peers by their secp256k1 node key, and consensus
messages are routed by the address derived from it. An adversary who recovers a
validator's ECDSA key therefore gets everything the transport can give: it completes
the handshake as that validator and signs syntactically perfect messages that recover
to its address. This test models exactly that adversary - full ECDSA compromise, no
Falcon key - and requires all four hot-path messages to be refused while the
post-quantum enforcement is armed, with a harvested seal replayed across message
kinds, blocks, heights, rounds, chains, and from another validator entirely.
The honest form of the claim: the transport is not post-quantum, and breaking it
does not buy a break of safety. It says nothing about liveness.
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