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d�ZdS(s?passlib.utils.scrypt -- scrypt hash frontend and help utilitiesi(
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    helper which validates a set of scrypt config parameters.
    scrypt will take ``O(n * r * p)`` time and ``O(n * r)`` memory.
    limitations are that ``n = 2**<positive integer>``, ``n < 2**(16*r)``, ``r * p < 2 ** 30``.

    :param n: scrypt rounds
    :param r: scrypt block size
    :param p: scrypt parallel factor
    i
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||||�S(s4run SCrypt key derivation function using specified parameters.

    :arg secret:
        passphrase string (unicode is encoded to bytes using utf-8).

    :arg salt:
        salt string (unicode is encoded to bytes using utf-8).

    :arg n:
        integer 'N' parameter

    :arg r:
        integer 'r' parameter

    :arg p:
        integer 'p' parameter

    :arg keylen:
        number of bytes of key to generate.
        defaults to 32 (the internal block size).

    :returns:
        a *keylen*-sized bytes instance

    SCrypt imposes a number of constraints on it's input parameters:

    * ``r * p < 2**30`` -- due to a limitation of PBKDF2-HMAC-SHA256.
    * ``keylen < (2**32 - 1) * 32`` -- due to a limitation of PBKDF2-HMAC-SHA256.
    * ``n`` must a be a power of 2, and > 1 -- internal limitation of scrypt() implementation

    :raises ValueError: if the provided parameters are invalid (see constraints above).

    .. warning::

        Unless the third-party ``scrypt <https://pypi.python.org/pypi/scrypt/>``_ package
        is installed, passlib will use a builtin pure-python implementation of scrypt,
        which is *considerably* slower (and thus requires a much lower / less secure
        ``n`` value in order to be usuable). Installing the :mod:`!scrypt` package
        is strongly recommended.
    tparamtsecrettsalti
skeylen must be at least 1skeylen too large, must be <= %d(RRRt
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    Load pure-python scrypt implementation built into passlib.
    i
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    Try to import the ctypes-based scrypt hash function provided by the
    ``scrypt <https://pypi.python.org/pypi/scrypt/>``_ package.
    i(
thashNRsJ'scrypt' package failed to import correctly (possible installation issue?)s5'scrypt' package is too old (lacks ``hash()`` method)(RRtImportErrortstrR
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    set backend for scrypt(). if name not specified, loads first available.

    :raises ~passlib.exc.MissingBackendError: if backend can't be found

    .. note:: mainly intended to be called by unittests, and scrypt hash handler
    tanyNtdefaulttdryrunsno scrypt backends availablesunknown scrypt backend: %rsscrypt backend %r not available(	tbackend_valuest_set_backendRtMissingBackendErrort_backend_loaderstgetRtbackendR(tnameR#tloaderR((sB/usr/lib/python2.7/site-packages/passlib/crypto/scrypt/__init__.pyR%�s&











	




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