Hash tree

Term tree hashes ( TTH; also tiger Trees ) are hash functions, which make it possible to determine with a high probability of large files unique hash values ​​. A significant feature is that can be drawn from the calculated hash check more hash values ​​for smaller parts of the file.

The actual method of applying this next hash function hash Tiger, which is calculated for small parts of equal size of the file, respectively. The list of hash values ​​is again divided into parts and calculated from these parts of the hash. If this procedure is applied as many times, you get a Roothash, which is used as unique identifier of the file. This value could be stored eg in a list of downloads of a open source project. The actual download can take place over a P2P network, no matter what size take place the partial downloads. You can always check if the partner provides a list of hashes of the appropriate size. The custom client can verify the hash list based on the Roothashes.

Apply Tiger Tree hashes, for example, in the P2P Clients Direct Connect and Shareaza.

The general procedure for creating stepped hashes was invented by Ralph Merkle.

In text representation of the TTH values ​​are usually given as a Base32 string, either directly or as a URN, for example,

For the 0 -byte file.

• Hash