Groestl Algorithm | cryptocurrencies, blockchains & live prices

Groestl is a cryptographic hash function that was one of the five finalists in the NIST SHA-3 competition. It was designed by Praveen Gauravaram, Lars Knudsen, Krystian Matusiewicz, Florian Mendel, Christian Rechberger, Martin Schläffer, and Søren S. Thomsen. The algorithm is built on a wide-pipe Merkle-Damgård construction and uses two distinct AES-based permutations, P and Q, in its compression function. Groestl processes data in blocks and applies multiple rounds of substitution, shift, mix, and key-addition operations borrowed from the Advanced Encryption Standard (AES), adapted to work within a hash function context.

One of Groestl's most distinctive properties is its heavy reliance on AES operations, which allows it to benefit from AES-NI hardware acceleration instructions available in modern CPUs. This makes Groestl particularly fast on processors that support these instruction sets, while remaining computationally intensive on hardware that lacks AES acceleration. The algorithm provides strong security guarantees with no practical attacks found against its full-round version. Its large internal state and wide-pipe design offer substantial security margins against collision and preimage attacks. In the context of cryptocurrency mining, Groestl's AES-dependent design provides a degree of ASIC resistance, as efficient mining benefits significantly from AES hardware support.

Groestl is most widely known in the cryptocurrency space as a component of the X11, X13, X15, and X17 chained hashing algorithms, where it serves as one of the individual hash functions in the sequence. It was also used as the primary algorithm by Groestlcoin (GRS), one of the earliest cryptocurrencies to specifically leverage Groestl for ASIC-resistant mining. Groestlcoin launched in 2014 and became a pioneer in adopting Segregated Witness (SegWit) and Lightning Network. The algorithm's presence as a SHA-3 finalist gave it strong academic credibility, and its AES-based design influenced the development of subsequent hash functions in both traditional cryptography and blockchain applications.