Can I post a transaction to the EOS blockchain that is signed using keys that aren't associated with an existing account? How does the blockchain detect these transactions?
According to the current documentation on GitHub, no.
An account is a human-readable name that is stored on the blockchain. It can be owned by an individual or group of individuals depending on permissions configuration. An account is required to transfer or otherwise push a transaction to the blockchain.
You can send it but it will be rejected by nodeos due to invalid signature.
Did you try to do that already and got an error? because I think the question makes sense since we can have keys associated with permissions, not accounts. (maybe my state is false and I misunderstood something) May 8, 2018 at 20:21
1According to Dan Larimer on Telegram, the Block Producers validate that the signing keys belong to a valid account and reject the transaction if they cannot find a matching account. I believe it is related to enforcing permissions and the like in the BP code. May 8, 2018 at 20:35