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What is libkeccak?

libkeccak is a collection of cryptographic constructions based on the Keccak permutation, such as the SHA-3 hash function. The library is designed to be modular and configurable, allowing many configurations of constructions to be built.

libkeccak implements the following constructions:

• The Keccak-p permutation for state sizes of 25, 50, 100, 200, 400, 800, and 1600 bits (see [1] and [2]).
• The Sponge construction
• The Duplex construction
• Hash functions based on the Sponge construction
• eXtendable Output Functions (XOF) based on the Sponge construction

libkeccak also provides concrete implementations for the hash functions and XOFs described in NIST FIPS 202 (see [1]):

• Hash functions:
  • SHA3-224
  • SHA3-256
  • SHA3-384
  • SHA3-512
• XOFs:
  • SHAKE128
  • SHAKE256
  • RawSHAKE128
  • RawSHAKE256

Hash function configurations are also provided for the hash functions defined by the Keccak team which were submitted in the SHA-3 competition:

• Keccak-224
• Keccak-256
• Keccak-384
• Keccak-512

These hash functions differ from the final SHA-3 hash functions only in that the SHA-3 functions append two additional bits to each message, whereas the Keccak hash functions do not.