File size: 3,527 Bytes
3a5cf48 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 | from __future__ import absolute_import, division, print_function, unicode_literals
import unicodedata
try:
from itertools import izip_longest
except ImportError:
from itertools import zip_longest as izip_longest
try:
from urllib.parse import quote, urlencode
except ImportError:
from urllib import quote, urlencode
def build_uri(secret, name, initial_count=None, issuer_name=None,
algorithm=None, digits=None, period=None):
"""
Returns the provisioning URI for the OTP; works for either TOTP or HOTP.
This can then be encoded in a QR Code and used to provision the Google
Authenticator app.
For module-internal use.
See also:
https://github.com/google/google-authenticator/wiki/Key-Uri-Format
:param secret: the hotp/totp secret used to generate the URI
:type secret: str
:param name: name of the account
:type name: str
:param initial_count: starting counter value, defaults to None.
If none, the OTP type will be assumed as TOTP.
:type initial_count: int
:param issuer_name: the name of the OTP issuer; this will be the
organization title of the OTP entry in Authenticator
:type issuer_name: str
:param algorithm: the algorithm used in the OTP generation.
:type algorithm: str
:param digits: the length of the OTP generated code.
:type digits: int
:param period: the number of seconds the OTP generator is set to
expire every code.
:type period: int
:returns: provisioning uri
:rtype: str
"""
# initial_count may be 0 as a valid param
is_initial_count_present = (initial_count is not None)
# Handling values different from defaults
is_algorithm_set = (algorithm is not None and algorithm != 'sha1')
is_digits_set = (digits is not None and digits != 6)
is_period_set = (period is not None and period != 30)
otp_type = 'hotp' if is_initial_count_present else 'totp'
base_uri = 'otpauth://{0}/{1}?{2}'
url_args = {'secret': secret}
label = quote(name)
if issuer_name is not None:
label = quote(issuer_name) + ':' + label
url_args['issuer'] = issuer_name
if is_initial_count_present:
url_args['counter'] = initial_count
if is_algorithm_set:
url_args['algorithm'] = algorithm.upper()
if is_digits_set:
url_args['digits'] = digits
if is_period_set:
url_args['period'] = period
uri = base_uri.format(otp_type, label, urlencode(url_args).replace("+", "%20"))
return uri
def _compare_digest(s1, s2):
differences = 0
for c1, c2 in izip_longest(s1, s2):
if c1 is None or c2 is None:
differences = 1
continue
differences |= ord(c1) ^ ord(c2)
return differences == 0
try:
# Python 3.3+ and 2.7.7+ include a timing-attack-resistant
# comparison function, which is probably more reliable than ours.
# Use it if available.
from hmac import compare_digest
except ImportError:
compare_digest = _compare_digest
def strings_equal(s1, s2):
"""
Timing-attack resistant string comparison.
Normal comparison using == will short-circuit on the first mismatching
character. This avoids that by scanning the whole string, though we
still reveal to a timing attack whether the strings are the same
length.
"""
s1 = unicodedata.normalize('NFKC', s1)
s2 = unicodedata.normalize('NFKC', s2)
return compare_digest(s1.encode("utf-8"), s2.encode("utf-8"))
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