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Description:

passwordmeter 0.1.8

A configurable, extensible password strength measuring library.

Project

Homepage: https://github.com/cadithealth/passwordmeter
Bugs: https://github.com/cadithealth/passwordmeter/issues

TL;DR
Install:
$ pip install passwordmeter
Use from within an application with the default factors:
import passwordmeter

strength, improvements = passwordmeter.test(sys.argv[1])

if strength < 0.5:
print 'Your password is too weak.'
Use on the command line:
$ pwm 'password'
Password strength: 0.132549901057 (Extremely weak)
Possible improvements:
- Use a good mix of numbers, letters, and symbols
- Avoid using one of the ten thousand most common passwords
- Use a good mix of UPPER case and lower case letters

Overview
The main function provided by the passwordmeter package is the
Meter.test() method, which returns a tuple of (float, dict). The
float is the strength of the password in the range 0 to 1 (inclusive),
where 0 is extremely weak and 1 is extremely strong. The second
parameter, which may be None, is a dictionary of ways the password
could be improved. The keys of the dict are general “categories” of
ways to improve the password (e.g. “length”) that are fixed strings,
and the values are internationalizable strings that are human-friendly
descriptions and possibly tailored to the specific password.
A password’s strength is determined by doing a weighted, skewed,
curved average of a set of “factors”. The Meter constructor takes a
settings dictionary that configures, customizes, and/or supplements
the default set of factors.
The passwordmeter.test is a helper function that simply uses the
default settings to test the strength of a password, and is
effectively a shorthand for Meter().test(...).
For example, to use a custom selection of factors:
import passwordmeter

# use only the 'length' and 'charmix' factors
meter = passwordmeter.Meter(settings=dict(factors='length,charmix'))

strength, improvements = meter.test('s3cr3t p4ssW0RD!')

Settings
The settings attribute to the Meter constructor is a dictionary
with the following keys:

factors:
This is a comma-separated list of factors to use in calculating the
strength of a password. Each element in the list is either the name
of a known factor or a symbol-spec as defined by the asset module. See
passwordmeter.DEFAULT_FACTORS for the default list of factors
(and their names).
For example, to use only the ‘length’ factor and a custom factor:
import passwordmeter

class SillyFactor(passwordmeter.Factor):
category = 'silly'
def test(self, value, extra):
if value == 'silly':
return (0, 'That is a silly password!')
return (1, None)

meter = passwordmeter.Meter(
settings=dict(factors=['length', SillyFactor]))

# or, same thing, but using an asset-spec:

meter = passwordmeter.Meter(
settings=dict(factors='length,mypackage.SillyFactor'))

factor.{NAME}.{ATTRIBUTE}:
Set a factor’s attribute during initialization. If a setting in the
form factor.{NAME}.class is specified for a factor not listed in
the factors setting, the factor will be auto-added to the list of
factors. This is the preferred mechanism to add a custom factor to
the default list.
The following attributes are “special” (all are optional):

Attribute
Interpretation

factor.{NAME}.class
Specifies the asset-spec for the factory that
can generate a Factor of this type.

factor.{NAME}.weight
Specifies the relative weight of this factor
(default: 1).

factor.{NAME}.skew
Adds the specified amount to factor score
(default: 0).

factor.{NAME}.spread
Multiplies the factor score by the specified
amount – similar to weight, but is applied
before clipping (default: 1).

factor.{NAME}.clipmin
Force a minimum score for this factor
(default: 0).

factor.{NAME}.clipmax
Force a maximum score for this factor
(default: 1.3).

factor.{NAME}.category
Override the default improvement category.

The following example settings in an INI file will give the length
factor additional weight as well as adding the “mypkg.MyFactor”
custom factor (initialized with the parameter msg set to
'abort') to the meter’s list:
factor.length.weight = 2.5
factor.cust.class = mypkg.MyFactor
factor.cust.msg = abort

pessimism:
The password strength engine weights low scores higher than high
scores. The degree to which the engine weights low scores is set by
the pessimism setting, which defaults to 10 – the higher, the
more a low score will pull the average score down. For example, with
the default pessimism of 10, the two scores 0.75 and 0.25 will be
averaged to 0.4 (instead of the true average of 0.5).

threshold:
Specifies the maximum score for which improvement messages should be
returned. If not specified, all possible improvements will be
returned, even if the relevant factor returned a perfect score (1.0
or greater).

Custom Factors
A custom factor should subclass passwordmeter.Factor, implement the
test method, and have a unique category (string) attribute.
The test method takes two parameters: the value to be tested, and
an opaque extra parameter that is supplied by the calling
application (and can be ignored if not needed). It should return a
tuple of (float, str).
The first element (float) of the return tuple must be greater or equal
to zero. Although it should generally not be greater than 1.0, a
factor may return a greater value: this is used to artificially
boost the strength of the total outcome relative to the other factors
if applicable. Note, however, that the Meter class will always clip
the final outcome to the inclusive range [0, 1].
The second element of the return tuple should be a string, which is a
description of how to improve the provided password. This string can
be None if no known way exists to improve this password for this
specific factor. Note that Meter class will associate this description
with the factor’s category in the final outcome.