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as i understand it, merkle trees are useful for operations within individual blocks, but do they have any use outside of each block? for example, are the merkle-roots from each block ever used in combination for any other purposes such as blockchain validation?
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The merkle tree means that you can verify the existence of a transaction in a block while only having the header, the transaction, and the merkle tree itself. It allows SPV clients to act extremely quickly and securely while only using the bare minimum of bandwidth. MultiBit is a SPV client that works in this way, and is extremely quick as a direct result.
1thanks. spv uses bloom filters and the merkle paths within the relevant blocks to prove that the transactions specified by the peer really did occur as claimed. however i'm asking if this is the only way that merkle trees are used in bitcoin? ie are merkle trees only ever used within a block and never across more than one block, for example? – mulllhausen – 2013-12-09T10:55:51.643
Not at the present, the transactions within a block are the only place I'm aware of that Merkle Trees exist. – Anonymous – 2013-12-09T11:04:31.173
Actually you only need the branch for your transaction and not the whole tree. – Luca Matteis – 2014-02-07T11:16:53.587