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"""
Password generation for the IPython notebook.
"""
#-----------------------------------------------------------------------------
# Imports
#-----------------------------------------------------------------------------
# Stdlib
import getpass
import hashlib
import random
# Our own
from IPython.core.error import UsageError
from IPython.utils.py3compat import encode
#-----------------------------------------------------------------------------
# Globals
#-----------------------------------------------------------------------------
# Length of the salt in nr of hex chars, which implies salt_len * 4
# bits of randomness.
salt_len = 12
#-----------------------------------------------------------------------------
# Functions
#-----------------------------------------------------------------------------
def passwd(passphrase=None, algorithm='sha1'):
"""Generate hashed password and salt for use in notebook configuration.
In the notebook configuration, set `c.NotebookApp.password` to
the generated string.
Parameters
----------
passphrase : str
Password to hash. If unspecified, the user is asked to input
and verify a password.
algorithm : str
Hashing algorithm to use (e.g, 'sha1' or any argument supported
by :func:`hashlib.new`).
Returns
-------
hashed_passphrase : str
Hashed password, in the format 'hash_algorithm:salt:passphrase_hash'.
Examples
--------
>>> passwd('mypassword')
'sha1:7cf3:b7d6da294ea9592a9480c8f52e63cd42cfb9dd12'
"""
if passphrase is None:
for i in range(3):
p0 = getpass.getpass('Enter password: ')
p1 = getpass.getpass('Verify password: ')
if p0 == p1:
passphrase = p0
break
else:
print('Passwords do not match.')
else:
raise UsageError('No matching passwords found. Giving up.')
h = hashlib.new(algorithm)
salt = ('%0' + str(salt_len) + 'x') % random.getrandbits(4 * salt_len)
h.update(encode(passphrase, 'utf-8') + encode(salt, 'ascii'))
return ':'.join((algorithm, salt, h.hexdigest()))
def passwd_check(hashed_passphrase, passphrase):
"""Verify that a given passphrase matches its hashed version.
Parameters
----------
hashed_passphrase : str
Hashed password, in the format returned by `passwd`.
passphrase : str
Passphrase to validate.
Returns
-------
valid : bool
True if the passphrase matches the hash.
Examples
--------
>>> from IPython.lib.security import passwd_check
>>> passwd_check('sha1:0e112c3ddfce:a68df677475c2b47b6e86d0467eec97ac5f4b85a',
... 'mypassword')
True
>>> passwd_check('sha1:0e112c3ddfce:a68df677475c2b47b6e86d0467eec97ac5f4b85a',
... 'anotherpassword')
False
"""
try:
algorithm, salt, pw_digest = hashed_passphrase.split(':', 2)
except (ValueError, TypeError):
return False
try:
h = hashlib.new(algorithm)
except ValueError:
return False
if len(pw_digest) == 0:
return False
h.update(encode(passphrase, 'utf-8') + encode(salt, 'ascii'))
return h.hexdigest() == pw_digest
|
