Grøstl is a cryptographic hash function submitted to the NIST hash function competition by Praveen Gauravaram, Lars Knudsen, Krystian Matusiewicz, Florian Mendel, Christian Rechberger, Martin Schläffer, and Søren S. Thomsen.
According to the submission document, the name "Grøstl" is a multilingual play-on-words, referring to an Austrian dish that is very similar to hash (food).
Like other hash functions in the MD5/SHA family, Grøstl divides the input into blocks and iteratively computes hi = f(hi−1, mi).
This is equivalent to applying a final iteration of the compression function using an all-zero message block m, followed by a (cryptographically insignificant) exclusive-or with the fixed constant Q(0).
Even a small change in the message will (with overwhelming probability) result in a mostly different hash, due to the avalanche effect.