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Python implementation of Ascon

This is a Python3 implementation of Ascon v1.2, an authenticated cipher and hash function.


Ascon is a family of authenticated encryption (AEAD) and hashing algorithms designed to be lightweight and easy to implement, even with added countermeasures against side-channel attacks. It was designed by a team of cryptographers from Graz University of Technology, Infineon Technologies, and Radboud University: Christoph Dobraunig, Maria Eichlseder, Florian Mendel, and Martin Schläffer.

Ascon has been selected as the primary choice for lightweight authenticated encryption in the final portfolio of the CAESAR competition (2014–2019) and is currently competing in the NIST Lightweight Cryptography competition (2019–).

Find more information, including the specification and more implementations here:


This is a simple reference implementation of Ascon v1.2 as submitted to the NIST LWC competition that includes

  • Three family members for authenticated encryption:

    • Ascon-128
    • Ascon-128a
    • Ascon-80pq
  • Four hashing algorithms: hash function variants with fixed 256-bit (Hash) or variable (Xof) output lengths

    • Ascon-Hash
    • Ascon-Hasha
    • Ascon-Xof
    • Ascon-Xofa


  • Implements the seven family members as well as the underlying permutation:

    • ascon_encryption()/ascon_decrypt() for authenticated encryption,
    • ascon_hash() for hashing,
    • ascon_permutation for the underlying permutation.

    By default, prints the results of encrypting and hashing some example strings.

    • debug = True|False: Set this variable to print the intermediate state after each phase of the encryption/hashing process.
    • debugpermutation = True|False: Set this variable to print the intermediate state after each step of the permutation's round function.
  • Produces result files for the Known Answer Tests (KATs) defined for the NIST LWC competition (call for algorithms, test vector generation code).

    Call with the name of the target algorithm (see above) as first parameter, default is Ascon-128.

    Results are written to

    • LWC_AEAD_KAT_{klenbits}_{nlenbits}.txt for authenticated encryption,
    • LWC_HASH_KAT_{hlenbits}.txt for hashing.