Metadata-Version: 1.1
Name: kravatte
Version: 0.9.2
Summary: Kravatte Encryption Authentication Tools
Home-page: https://github.com/inmcm/kravatte
Author: Michael Calvin McCoy
Author-email: calvin.mccoy@protonmail.com
License: MIT license
Download-URL: https://github.com/inmcm/kravatte/archive/0.9.2.tar.gz
Description-Content-Type: UNKNOWN
Description: Kravatte Achouffe Cipher Suite in Python/NumPy
        ==============================================
        
        An implementation, in Python3, of the
        `Kravatte <https://keccak.team/kravatte.html>`__ pseudo-random function
        and associated modes based on the `Farfalle
        PRF <https://eprint.iacr.org/2016/1188.pdf>`__ system. At its core,
        Kravatte accepts a user defined secret key and a sequence of input bytes
        to generate pseudo-random output of arbitrary size.
        
        Kravatte makes use of the
        `Keccak <https://keccak.team/files/Keccak-reference-3.0.pdf>`__
        permutation, most notably used in NIST’s `FIPS 202 SHA-3
        algorithm <https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.202.pdf>`__.
        Because the underlying structure of Keccak function works on a
        three-dimensional state of 1600 bits, it maps well to a 5x5 matrix of
        64-bit unsigned integers. As such, the `NumPy <http://www.numpy.org>`__
        computational library is a natural fit to quickly manipulate such a
        structure and thus is a hard requirement.
        
        This implementation reflects the updated, more secure Kravatte
        **Achouffe** released in late 2017. The older “Kravatte 6644” logic is
        available within this repo as well.
        
        Installation
        ------------
        Kravatte can be easily installed from `pypi <https://pypi.org/project/kravatte/>`__ via `pip`:
        
        .. code:: bash
        
            $ pip install kravatte
        
        If `pip` is unavailable, this repo can be cloned and setup can be done manually:
        
        .. code:: bash
        
            $ python setup.py install
        
        
        Kravatte Object
        ---------------
        
        The basic Kravatte object operates on two Keecak-1600 state matrices;
        the collector state and the key state. Instantiating a Kravatte object
        initializes the key state with provided user key and sets the collector
        state to zeros.
        
        .. code:: python
        
            In [1]: from kravatte import Kravatte
            In [2]: my_krav = Kravatte(b'1234567890')
        
        The newly initialized Kravatte object is now ready to accept input
        strings of bytes for absorption into the collector state via the
        ``collect_message`` method. Repeated calls to ``collect_message`` are
        equivalent to ``B ◦ A`` sequences as described in the the Farfalle
        spec:
        
        .. code:: python
        
            In [3]: input_a = b'The quick brown fox jumps over the lazy dog'
            In [4]: my_krav.collect_message(input_a)
            In [5]: input_b = b'3533392d36302d35313235'
            In [6]: my_krav.collect_message(input_b)
        
        Once absorbing message strings is complete, the Kravatte object can
        produce an arbitrary number of pseudo-random output bytes via the
        ``generate_digest`` method. Those bytes are then available in the
        ``digest`` attribute:
        
        .. code:: python
        
            In [7]: output_bytes = 64
            In [8]: my_krav.generate_digest(output_bytes)
            In [9]: from binascii import hexlify
            In [10]: hexlify(my_krav.digest)
            Out[10]: b'8a0fc89899e058dedd368b60111bf4958f4f24216bbac76936471e6f7c3958b881c38c8e829ff07bf137701917b3e49ab392e93f3b2abfc714f90c0ca023124d'
        
        The absorb/output sequence can be restarted with another call to
        ``collect_message``. This clears the collector state and resets the key
        state to its initialized value. Alternatively, the user may change to a
        new secret key with the ``update_key`` method to reinitialize the key
        state used at the start of message absorption.
        
        MAC
        ---
        
        The most basic mode of Kravatte is an authenticated pseudo-random
        function (PRF). Kravatte can absorb an arbitrary sized user message and
        key, and output an arbitrary collection of pseudo-random bytes that can
        act as a message authentication code.
        
        .. code:: python
        
            In [1] from kravatte import mac
            In [2] from binascii import hexlify
            In [3] message = b'Attack at Dawn!'
            In [4] key = b'something_secret'
            In [5] mac_size = 64
            In [6] g = mac(key, message, mac_size)
            In [7] hexlify(g)
            Out[7] b'24f61fc5fd38fef7f3d799ed72b24578c4479e1c035c70d8bc55ce23d74124255d5e8a0c5dd33aa36d5289f1e4e995a19be804d97bb338fa875e01e3c2d2dd51'
        
        Kravatte-SIV
        ------------
        
        Kravatte-SIV mode is a method of authenticated encryption with
        associated metadata (AEAD) that allows for encrypting a provided
        plaintext with a secret shared key and an arbitrary metadata value.
        Encryption generates an equal length ciphertext and fixed length tag
        that can be used to validate the plaintext at decryption. Metadata
        values can be shared for different key/message combinations with
        understanding that the more a value is used, the greater the chance of a
        tag collision. 
        
        Encrypt
        ~~~~~~~
        
        .. code:: python
        
            In [1] from kravatte import siv_wrap, siv_unwrap
            In [2] from binascii import hexlify
            In [3] from datetime import datetime
            In [4] message = b'Attack at Dawn!'
            In [5] key = b'something_secret'
            In [6] metadata = str(datetime.now()).encode()
            In [7] ciphertext, tag = siv_wrap(key, message, metadata)
            In [8] hexlify(ciphertext)
            Out[8] b'79f7bd89a7cb7af1892ea51c531f4b'
            In [9] hexlify(tag)
            Out[9] b'37c7e11f0c9c744e7c113590fdfba7737cb38b629ef6901df22d6994340e89eas'
        
        Decrypt
        ~~~~~~~
        
        .. code:: python
        
            In [10] plaintext, tag_valid = siv_unwrap(key, ciphertext, tag, metadata)
            In [11] plaintext
            Out[11] b'Attack at Dawn!'
            In [12] tag_valid
            Out[12] True
        
        Kravatte-SAE
        ------------
        
        Kravatte-SAE mode is a session based method of AEAD. Given a random
        nonce and secret key, this mode encrypts a sequence of plaintext
        messages and/or metadata into equal size ciphertexts and a validation
        tag. The sequence of plaintext/metadata is tracked as a history that
        builds a chain of authentication from message to message and requires
        all generated ciphertexts to be processed to fully decrypt and verify.
        
        A separate ``KravatteSAE`` class is provided that adds the history
        tracking for each encryption operation done via the ``sae_wrap`` method.
        
        Encrypt
        ~~~~~~~
        
        .. code:: python
        
            In [1]: from kravatte import KravatteSAE
            In [2]: from datetime import datetime
            In [3]: from binascii import hexlify
            In [4]: message_1 = b'Directions to my house:'
            In [5]: metadata_1 = str(datetime.now()).encode()
            In [6]: message_2 = b'Turn right on main street'
            In [7]: metadata_2 = str(datetime.now()).encode()
            In [8]: message_3 = b'Continue straight for 3500 miles'
            In [9]: metadata_3 = str(datetime.now()).encode()
            In [10]: message_4 = b'You have arrived at your destination'
            In [11]: metadata_4 = str(datetime.now()).encode()
            In [12]: nonce = b'a well chosen random number'
            In [13]: key = b'an even better random number'
            In [14]: KravSAE_wrapper = KravatteSAE(nonce, key)
            In [15]: ciphertext_1, tag_1 = KravSAE_wrapper.sae_wrap(message_1, metadata_1)
            In [16]: hexlify(ciphertext_1)
            Out[16]: b'7b8932a1c3673fcfe752631ef5b867843951514335de61'
            In [17]: hexlify(tag_1)
            Out[17]: b'3384885ca293925cc65a03fa10790420'
            In [18]: ciphertext_2, tag_2 = KravSAE_wrapper.sae_wrap(message_2, metadata_2)
            In [19]: hexlify(ciphertext_2)
            Out[19]: b'ab48882d4339c6def9d5d06f608db5318a87a417566c0b20bd'
            In [20]: hexlify(tag_2)
            Out[20]: b'347f5a152dcc9ccc3c19fa936067c3d2'
            In [21]: ciphertext_3, tag_3 = KravSAE_wrapper.sae_wrap(message_3, metadata_3)
            In [22]: hexlify(ciphertext_3)
            Out[22]: b'bc461f40db74705c10b1400b6a9967dd7164cbf774c196d5b649faf2bd792339'
            In [23]: hexlify(tag_3)
            Out[23]: b'6ba2faee4d2aa5654a054222a049d926'
            In [24]: ciphertext_4, tag_4 = KravSAE_wrapper.sae_wrap(message_4, metadata_4)
            In [25]: hexlify(ciphertext_4)
            Out[25]: b'1f451f51d9882f9f7674c37dace4036efd9efe39d6b58ccdf6b012ef988e4e1f2617479f'
            In [26]: hexlify(tag_4)
            Out[26]: b'5f3511f140b4ea36412c0e4b22d1c218'
        
        For decryption and validation, the ``sae_unwrap`` method accepts the
        ciphertext, original metadata, and validation tag to not only decrypt
        the plaintext, but return a boolean if the decrypted plaintext is valid
        within the chain of messages.
        
        Decrypt
        ~~~~~~~
        
        .. code:: python
        
            In [27]: KravSAE_unwrapper = KravatteSAE(nonce, key)
            In [28]: plaintext_1, check_tag_1 = KravSAE_unwrapper.sae_unwrap(ciphertext_1, metadata_1, tag_1)
            In [29]: plaintext_1
            Out[29]: b'Directions to my house:'
            In [30]: check_tag_1
            Out[30]: True
            In [31]: plaintext_2, check_tag_2 = KravSAE_unwrapper.sae_unwrap(ciphertext_2, metadata_2, tag_2)
            In [32]: plaintext_2
            Out[32]: b'Turn right on main street'
            In [33]: check_tag_2
            Out[33]: True
            In [34]: plaintext_3, check_tag_3 = KravSAE_unwrapper.sae_unwrap(ciphertext_3, metadata_3, tag_3)
            In [35]: plaintext_3
            Out[35]: b'Continue straight for 3500 miles'
            In [36]: check_tag_3
            Out[36]: True
            In [37]: plaintext_4, check_tag_4 = KravSAE_unwrapper.sae_unwrap(ciphertext_4, metadata_4, tag_4)
            In [38]: plaintext_4
            Out[38]: b'You have arrived at your destination'
            In [39]: check_tag_4
            Out[39]: True
        
        KravatteWBC
        -----------
        
        Kravatte Wide Block Cipher mode is symmetric block cipher mode where the user can specify
        the size of the block, an arbitrary `tweak` value input, and arbitrary secret key. The `KravatteWBC`
        object, once initialized can encrypt/decrypt messages of the given block size (or smaller). KravatteWBC
        is splits messages into left and right components and uses a 4-stage Feistal sequence to encrypt/decrypt.
        
        Encrypt and Decrypt
        ~~~~~~~~~~~~~~~~~~~
        
        .. code:: python
        
            In [1]: from kravatte import KravatteWBC
            In [2]: block_size = 64
            In [3]: my_tweak = b'tweak can be anything'
            In [4]: my_key = b'\x00' * 24
            In [5]: my_wbc = KravatteWBC(block_size, my_tweak, my_key)
            In [6]: c_block = my_wbc.encrypt(b'This is some random 64-byte text string to use in this example!!')
            In [7]: from binascii import hexlify
            In [8]: hexlify(c_block)
            Out[8]: b'2368fae1271e5c784537df331586d5d4daeeb34a6fe4ebea03cc1df7f9c0d79fcc709a9ff2199514f431da685e27658dbf6c5afed11ce5c8172f7615c19db1b9'
            In [9]: my_wbc.decrypt(c_block)
            Out[9]: b'This is some random 64-byte text string to use in this example!!'
        
        
        KravatteWBC-AE
        --------------
        
        KravatteWBC-AE is a variant of KravatteWBC that extends the desired block size by 16 bytes and 
        embeds authentication data. The tweak is replaced with arbitrary associated metadata. When the 
        block is decrypted it is also validated as being encrypted with same secret key.
        
        Encrypt and Decrypt
        ~~~~~~~~~~~~~~~~~~~
        
        .. code:: python
        
            In [1]: from datetime import datetime
            In [2]: from binascii import hexlify
            In [3]: my_key = b"Doesn't look like anything to me"
            In [4]: metadata = str(datetime.now()).encode()
            In [5]: message = b'These violent delights have violent ends'
            In [6]: len(message)
            Out[6]: 40
            In [7]: my_WBC_AE = KravatteWBC_AE(40, my_key)
            In [8]: ctext_ae = my_WBC_AE.wrap(message, metadata)
            In [9]: len(ctext_ae)
            Out[9]: 56
            In [10]: hexlify(ctext_ae)
            Out[10]: b'388623f7a7d3c044cda574063b4ff16edbdfc95cb449f335a1c5ad5ed37897aa2470f3575825a55df04cc1dab34b4feb03aa6d35f6190d62'
            In [11]: plaintext, validated = my_WBC_AE.unwrap(ctext_ae, metadata)
            In [12]: plaintext
            Out[12]: b'These violent delights have violent ends'
            In [13]: validated
            Out[13]: True
        
        
        KravatteOracle
        --------------
        
        KravatteOracle is simple pseduo-random number generator built from the Kravatte PRF primitive. Initialized
        with an authentication key, the KravatteOracle object absorbs an arbitrarily sized seed value into the
        collector state. From there, streams of random bytes can be generated on demand via the `random` method.
        The generator can be re-seeded at any point with the `seed_generator` method.
        
        Generate Random Numbers
        ~~~~~~~~~~~~~~~~~~~~~~~
        
        .. code:: python
        
            In [1]: my_psrng = KravatteOracle(my_seed, my_key)
            In [2]: my_key = b'1234'
            In [3]: my_seed = b'watermelon'
            In [4]: my_psrng = KravatteOracle(my_seed, my_key)
            In [5]: random_bytes = my_psrng.random(24)
            In [6]: hexlify(random_bytes)
            Out[6]: b'14a42ab5756efe61eae73893570b6736b392d0031a87e36d'
            In [7]: random_bytes = my_psrng.random(42)
            In [8]: hexlify(random_bytes)
            Out[8]: b'77d6308e18d57fb124e75602ced2e863e7de34c69ea57bec47efae84e85d0075c3ebbf7e535ec0fb096f'
        
        Re-seed Generator
        ~~~~~~~~~~~~~~~~~
        
        .. code:: python
        
            In [9]: my_psrng.seed_generator(b'apple')
            In [10]: random_bytes = my_psrng.random(18)
            In [11]: hexlify(random_bytes)
            Out[11]: b'3e108c3f627f561943893b6a3184e5b76472'
        
        
        Testing
        -------
        
        A full test suite is available in ``test_kravatte.py``. Assuming the ``kravatte`` module is installed, 
        tests can be invoked with pytest:
        
        .. code:: bash
        
            $ pytest -xvvv test_kravatte.py
        
        Test vectors were generated using the
        `KeccakTools <https://github.com/gvanas/KeccakTools>`__ C++ library
        available from the Keccak Team
        
        Caveats
        -------
        
        -  Being a Python implementation, performance on large files or data
           sets may be inadequate.
        -  The inputs and outputs of this implementation are limited to byte
           (8-bit) divisible sizes
        -  While security was top of mind during development, this
           implementation has not been fully audited for timing attacks, side
           channel attacks or other vulnerabilities. Other bugs not caught by
           the test cases may be present. Use in a production environment is not
           encouraged.
        
        If any of above are of concern, please check out the official
        `KeccakTools <https://github.com/gvanas/KeccakTools>`__ and `Keccak Code
        Package <https://github.com/gvanas/KeccakCodePackage>`__
        
Keywords: kravatte,farfalle,PRF,AEAD,MAC,crypto,encryption
Platform: UNKNOWN
Classifier: Development Status :: 4 - Beta
Classifier: Intended Audience :: Developers
Classifier: License :: OSI Approved :: MIT License
Classifier: Natural Language :: English
Classifier: Programming Language :: Python :: 3
Classifier: Programming Language :: Python :: 3.5
Classifier: Programming Language :: Python :: 3.6
