Bitcoin tree

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It uses a binary hash tree two child nodes under each node , usually has a data block size of bytes and uses the Tiger hash. From Wikipedia, the free encyclopedia. Type of data structure. Computer programming portal. Retrieved Lecture Notes in Computer Science. ISBN Google Wave Protocol. Archived from the original on January Designs, Codes and Cryptography. CiteSeerX S2CID When a replica is down for an extended period of time, or the machine storing hinted handoffs for an unavailable replica goes down as well, replicas must synchronize from one another.

In this case, Cassandra and Riak implement a Dynamo-inspired process called anti-entropy. In anti-entropy, replicas exchange Merkle trees to identify parts of their replicated key ranges which are out of sync. A Merkle tree is a hierarchical hash verification: if the hash over the entire keyspace is not the same between two replicas, they will exchange hashes of smaller and smaller portions of the replicated keyspace until the out-of-sync keys are identified.

This approach reduces unnecessary data transfer between replicas which contain mostly similar data. June Selected Areas in Cryptography. In Smart, Nigel ed. Istanbul, Turkey. March 4, Retrieved 23 September Listen to this article 5 minutes. This audio file was created from a revision of this article dated 17 September , and does not reflect subsequent edits.

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Tree data structures. Categories : Error detection and correction Cryptographic hash functions Hashing Trees data structures. Hidden categories: Articles with short description Short description is different from Wikidata All articles with unsourced statements Articles with unsourced statements from October Articles with hAudio microformats Spoken articles.

Namespaces Article Talk. Views Read Edit View history. Hash trees are also used in hash-based cryptography. The initial Bitcoin implementation of Merkle trees by Satoshi Nakamoto applies the compression step of the hash function to an excessive degree, which is mitigated by using Fast Merkle Trees.

A hash tree is a tree of hashes in which the leaves are hashes of data blocks in, for instance, a file or set of files. Nodes further up in the tree are the hashes of their respective children. For example, in the picture hash 0 is the result of hashing the concatenation of hash and hash Most hash tree implementations are binary two child nodes under each node but they can just as well use many more child nodes under each node.

Usually, a cryptographic hash function such as SHA-2 is used for the hashing. If the hash tree only needs to protect against unintentional damage, much less secure checksums such as CRCs can be used. In the top of a hash tree there is a top hash or root hash or master hash. Before downloading a file on a p2p network, in most cases the top hash is acquired from a trusted source, for instance a friend or a web site that is known to have good recommendations of files to download.

When the top hash is available, the hash tree can be received from any non-trusted source, like any peer in the p2p network. Then, the received hash tree is checked against the trusted top hash, and if the hash tree is damaged or fake, another hash tree from another source will be tried until the program finds one that matches the top hash. The main difference from a hash list is that one branch of the hash tree can be downloaded at a time and the integrity of each branch can be checked immediately, even though the whole tree is not available yet.

For example, in the picture, the integrity of data block 2 can be verified immediately if the tree already contains hash and hash 1 by hashing the data block and iteratively combining the result with hash and then hash 1 and finally comparing the result with the top hash. Similarly, the integrity of data block 3 can be verified if the tree already has hash and hash 0. This can be an advantage since it is efficient to split files up in very small data blocks so that only small blocks have to be re-downloaded if they get damaged.