The FPH (Fast Parallel Hash) schemes are, as their core is CSHAKE, which is a user-customizable (parameterized) SHAKE, which uses the Sakura construction. In t

The FPH (Fast Parallel Hash) schemes are, as their core is CSHAKE, which is a user-customizable (parameterized) SHAKE, which uses the Sakura construction. In the Sakura paper's conclusion, they state: "In the current FIPS 202 draft, the SHA-3 extendable-output functions chosen by NIST adopt SAKURA for sequential hashing as a special case of tree hashing." Similarly, the FIPS 202 document refers to SAKURA when it talks about the XOFs SHAKE128 and SHAKE256: "The two SHA-3 XOFs are also specified in a manner that allows for the development of dedicated variants. Moreover, the SHA-3 XOFs are compatible with the Sakura coding scheme for tree hashing in order to support the development of parallelizable variants of the XOFs, to be specified in a separate document." [1] [1] http://www.nist.gov/customcf/get_pdf.cfm?pub_id=919061 http://www.nist.gov/customcf/get_pdf.cfm?pub_id=919061