A hash chain is the successive application of a cryptographic hash function to a piece of data. In computer security, a hash chain is a method to produce many one-time keys from a single key or password. For non-repudiation a hash function can be applied successively to additional pieces of data in order to record the chronology of data's existence.
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Definition
A hash chain is a successive application of a cryptographic hash function
For example,
Applications
Lamport suggested the use of hash chains as a password protection scheme in an insecure environment. A server which needs to provide authentication may store a hash chain rather than a plain text password and prevent theft of the password in transmission or theft from the server. For example, a server begins by storing
An eavesdropper seeing
Binary hash chains
Binary hash chains are commonly used in association with a hash tree. A Binary hash chain takes two hash values as inputs, concatenates them and applies a hash function to the result, thereby producing a third hash value.
The above diagram shows a hash tree consisting of eight leaf nodes and the hash chain for the third leaf node. In addition to the hash values themselves the order of concatenation (right or left 1,0) or “order bits” are necessary to complete the hash chain.
Hashchain vs Blockchain
A hashchain when used within the context of a Blockchain are similar only as they both utilize a cryptographic hash function for creating a link between two nodes. However, a Blockchain (see Bitcoin) is more representative of an entire system, which includes among many things, specific approach to encapsulation of data, associated data permissions, and distribution of data via a consensus mechanism, for use as a public ledger.