# Tag Info

6

If the same standard hash function was used for both leaves and branch nodes, it would be easy to generate collisions and even second preimages. For example, let $M$ be a message which is longer than the segment size of the hash tree, but (for simplicity) no more than two segments long. Then the hash value of $M$ is calculated as H(M) = H_I(H_L(M_0) ...

4

The torrent tree hash is vulnerable to second pre-image attacks by itself, even with 00 padding. I won't repeat Ilmari Karonen's answer, who already explained that part very well. But it isn't used to identify the data by itself: The original publisher of the content-file set creates a so-called Merkle torrent which is a torrent file that contains a ...

4

The Tree Hash EXchange format (THEX) spec (which seems to have dropped off the web, but is still available on archive.org) says, in section 2: 2.1 Hash Functions The strength of the hash tree construct is only as strong as the underlying hash algorithm. Thus, it is RECOMMENDED that a secure hash algorithm such as SHA-1 be used as the basis of ...

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