Hash chain definition
A hash chain is a computer security process by which a cryptographic hash function (CHF) is repeatedly applied to a data asset. Hashing is a cryptography method that transforms a given key or character string into a fixed-length value. Unlike encryption, hashing is a one-way function and can’t be decrypted. A hash chain is a sequence of hashes. By creating a successive chain, hash cryptography increases the security of the data and makes it hard for a snooping hacker to hijack it.
How a hash chain works
- A hash chain produces many one-time keys from one key or password.
- A user supplies individual input on the first session or interaction (e.g., a password).
- The input is encoded using a hash function (e.g., SHA, BLAKE3, or MD5 algorithms). The code becomes fixed length.
- On their next session, authenticating data is added to the original input.
- Over a set of sessions, the individual hash inputs form a hash chain that authenticates the user in a secure, reliable way. The hashed strings are meaningless to a hacker.
Where hash chains are used
- Databases and data storage systems
- Password storage
- Digital signatures
See also: encryption, file hash