def _prepare_rounds(self, handler, opts, settings):
"helper for prepare_default_settings"
mn = opts.get("min_rounds")
mx = opts.get("max_rounds")
rounds = settings.get("rounds")
if rounds is None:
df = opts.get("default_rounds") or mx or mn
if df is not None:
vr = opts.get("vary_rounds")
if vr:
if isinstance(vr, str):
rc = getattr(handler, "rounds_cost", "linear")
vr = int(vr.rstrip("%"))
#NOTE: deliberately strip >1 %,
#in case an interpolation-escaped %%
#makes it through to here.
assert 0 <= vr < 100
if rc == "log2":
#let % variance scale the number of actual rounds, not the logarithmic value
df = 2**df
vr = int(df*vr/100)
lower = int(logb(df-vr,2)+.5) #err on the side of strength - round up
upper = int(logb(df+vr,2))
else:
assert rc == "linear"
vr = int(df*vr/100)
lower = df-vr
upper = df+vr
else:
lower = df-vr
upper = df+vr
if lower < 1:
lower = 1
if mn and lower < mn:
lower = mn
if mx and upper > mx:
upper = mx
if lower > upper:
#NOTE: this mainly happens when default_rounds>max_rounds, which shouldn't usually happen
rounds = upper
warn("vary default rounds: lower bound > upper bound, using upper bound (%d > %d)" % (lower, upper))
else:
rounds = rng.randint(lower, upper)
else:
rounds = df
if rounds is not None:
if mx and rounds > mx:
rounds = mx
if mn and rounds < mn: #give mn predence if mn > mx
rounds = mn
settings['rounds'] = rounds
def guess_rounds(rps, target):
return int(logb(rps*target,2)+.5)
'sys_bits',
'unix_crypt_schemes',
]
#=================================================================================
#constants
#=================================================================================
#: detect what we're running on
pypy_vm = hasattr(sys, "pypy_version_info")
jython_vm = sys.platform.startswith('java')
py3k_lang = sys.version_info >= (3,0)
py32_lang = sys.version_info >= (3,2)
#: number of bits in system architecture
sys_bits = int(logb(sys.maxint,2)+1.5)
assert sys_bits in (32,64), "unexpected sys_bits value: %r" % (sys_bits,)
#: list of names of hashes found in unix crypt implementations...
unix_crypt_schemes = [
"sha512_crypt", "sha256_crypt",
"sha1_crypt", "bcrypt",
"md5_crypt",
"bsdi_crypt", "des_crypt"
]
#: list of rounds_cost constants
rounds_cost_values = [ "linear", "log2" ]
#: special byte string containing all possible byte values, used in a few places.
#XXX: treated as singleton by some of the code for efficiency.