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Diffstat (limited to 'docs/hazmat/primitives/key-derivation-functions.rst')
| -rw-r--r-- | docs/hazmat/primitives/key-derivation-functions.rst | 26 |
1 files changed, 14 insertions, 12 deletions
diff --git a/docs/hazmat/primitives/key-derivation-functions.rst b/docs/hazmat/primitives/key-derivation-functions.rst index dbca3a5b..607eeb29 100644 --- a/docs/hazmat/primitives/key-derivation-functions.rst +++ b/docs/hazmat/primitives/key-derivation-functions.rst @@ -755,7 +755,6 @@ Different KDFs are suitable for different tasks such as: .. code-block:: python >>> import os - >>> from cryptography.hazmat.primitives import hashes >>> from cryptography.hazmat.primitives.kdf.scrypt import Scrypt >>> from cryptography.hazmat.backends import default_backend >>> backend = default_backend() @@ -764,9 +763,9 @@ Different KDFs are suitable for different tasks such as: >>> kdf = Scrypt( ... salt=salt, ... length=64, - ... n=1024, + ... n=2**14, ... r=8, - ... p=16, + ... p=1, ... backend=backend ... ) >>> key = kdf.derive(b"my great password") @@ -774,9 +773,9 @@ Different KDFs are suitable for different tasks such as: >>> kdf = Scrypt( ... salt=salt, ... length=64, - ... n=1024, + ... n=2**14, ... r=8, - ... p=16, + ... p=1, ... backend=backend ... ) >>> kdf.verify(b"my great password", key) @@ -789,14 +788,16 @@ Different KDFs are suitable for different tasks such as: :param int p: Parallelization parameter. The computational and memory cost of Scrypt can be adjusted by manipulating - the 3 parameters: n, r and p. In general, the memory cost of Scrypt is - affected by the values of both n and r while n also determines the number - of iterations performed. p increases the computational cost without - affecting memory usage. A more in-depth explanation of the 3 parameters can - be found `here`_. + the 3 parameters: ``n``, ``r``, and ``p``. In general, the memory cost of + Scrypt is affected by the values of both ``n`` and ``r``, while ``n`` also + determines the number of iterations performed. ``p`` increases the + computational cost without affecting memory usage. A more in-depth + explanation of the 3 parameters can be found `here`_. - :rfc:`7914` `recommends`_ values of r=8 and p=1 while scaling n to the - number appropriate for your system. + :rfc:`7914` `recommends`_ values of ``r=8`` and ``p=1`` while scaling ``n`` + to a number appropriate for your system. `The scrypt paper`_ suggests a + minimum value of ``n=2**14`` for interactive logins (t < 100ms), or + ``n=2**20`` for more sensitive files (t < 5s). :param backend: An instance of :class:`~cryptography.hazmat.backends.interfaces.ScryptBackend`. @@ -905,3 +906,4 @@ Interface .. _`HKDF paper`: https://eprint.iacr.org/2010/264 .. _`here`: https://stackoverflow.com/a/30308723/1170681 .. _`recommends`: https://tools.ietf.org/html/rfc7914#section-2 +.. _`The scrypt paper`: https://www.tarsnap.com/scrypt/scrypt.pdf |