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fix: Switch anonymous user ID hash from md5 to shake #26198

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merged 5 commits into from
Feb 10, 2021
Merged

fix: Switch anonymous user ID hash from md5 to shake #26198

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63240b1
refactor: switching hashing algorithm for md5 to shake
Jan 27, 2021
d5d30ec
fix: quality
Jan 27, 2021
874acdd
fix: tests hardcoded for shake algorithm
Jan 27, 2021
e80c93d
Update common/djangoapps/student/models.py
jinder1s Jan 29, 2021
19d1d40
Merge branch 'master' into msingh/refactor/hashing/md5/shake
jinder1s Feb 9, 2021
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12 changes: 10 additions & 2 deletions common/djangoapps/student/models.py
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Original file line number Diff line number Diff line change
Expand Up @@ -200,12 +200,20 @@ def anonymous_id_for_user(user, course_id, save=True):
monitoring.increment('temp_anon_uid_v2.fetched_existing')
else:
# include the secret key as a salt, and to make the ids unique across different LMS installs.
hasher = hashlib.md5()
hasher = hashlib.shake_128()
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No test changes?

Incidentally, I'd call this a fix in the nomenclature of Conventional Commits.

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Oh no, yep, there will be.

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hmmm, I can kinda see, but still think it doesn't really work. We are not fixing a bug, we are just moving to a better algorithm.

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Honestly, I'm not real thrilled by the options suggested in that spec. :-) This isn't a feature, and it's not exactly a bug fix, it's... an "improvement".

# This is one of several uses of SECRET_KEY.
#
# Impact of exposure: If a person has the SECRET_KEY and a user's `id`
# they can correlate the users anonymous user IDs across any courses they have participated in.
#
# Rotation process: Can be rotated at will. There is a small chance (on the order of 1%) that
# any given new user will be assigned multiple anonymous user IDs during the period in which
# servers are configured with a mix of old and new keys.
hasher.update(settings.SECRET_KEY.encode('utf8'))
hasher.update(text_type(user.id).encode('utf8'))
if course_id:
hasher.update(text_type(course_id).encode('utf-8'))
anonymous_user_id = hasher.hexdigest()
anonymous_user_id = hasher.hexdigest(16) # pylint: disable=too-many-function-args

if save is True:
try:
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6 changes: 3 additions & 3 deletions lms/djangoapps/courseware/tests/test_module_render.py
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Expand Up @@ -1991,7 +1991,7 @@ def test_per_student_anonymized_id(self, descriptor_class):
self.assertEqual(
# This value is set by observation, so that later changes to the student
# id computation don't break old data
'5afe5d9bb03796557ee2614f5c9611fb',
'de619ab51c7f4e9c7216b4644c24f3b5',
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self._get_anonymous_id(CourseKey.from_string(course_id), descriptor_class)
)

Expand All @@ -2000,14 +2000,14 @@ def test_per_course_anonymized_id(self, descriptor_class):
self.assertEqual(
# This value is set by observation, so that later changes to the student
# id computation don't break old data
'e3b0b940318df9c14be59acb08e78af5',
'0c706d119cad686d28067412b9178454',
self._get_anonymous_id(CourseKey.from_string('MITx/6.00x/2012_Fall'), descriptor_class)
)

self.assertEqual(
# This value is set by observation, so that later changes to the student
# id computation don't break old data
'f82b5416c9f54b5ce33989511bb5ef2e',
'e9969c28c12c8efa6e987d6dbeedeb0b',
self._get_anonymous_id(CourseKey.from_string('MITx/6.00x/2013_Spring'), descriptor_class)
)

Expand Down