utils: Remove make_safe_digest wrapper.

It’s unclear what was supposed to be “safe” about this wrapper.  The
hashlib API is fine without it, and we don’t want to encourage further
use of SHA-1.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

docs/subsystems/caching.md

@@ -61,12 +61,12 @@ framework; as you can see, it's very little code on top of our
 
 ```python
 def user_profile_cache_key_id(email: str, realm_id: int) -> str:
-    return u"user_profile:%s:%s" % (make_safe_digest(email.strip()), realm_id,)
+    return f"user_profile:{hashlib.sha1(email.strip().encode()).hexdigest()}:{realm_id}"
 
-def user_profile_cache_key(email: str, realm: 'Realm') -> str:
+def user_profile_cache_key(email: str, realm: "Realm") -> str:
     return user_profile_cache_key_id(email, realm.id)
 
-@cache_with_key(user_profile_cache_key, timeout=3600*24*7)
+@cache_with_key(user_profile_cache_key, timeout=3600 * 24 * 7)
 def get_user(email: str, realm: Realm) -> UserProfile:
     return UserProfile.objects.select_related().get(
         email__iexact=email.strip(), realm=realm)

zerver/data_import/rocketchat.py

@@ -1,3 +1,4 @@
+import hashlib
 import logging
 import os
 import random
@@ -33,7 +34,7 @@ from zerver.data_import.user_handler import UserHandler
 from zerver.lib.emoji import name_to_codepoint
 from zerver.lib.markdown import IMAGE_EXTENSIONS
 from zerver.lib.upload.base import sanitize_name
-from zerver.lib.utils import make_safe_digest, process_list_in_batches
+from zerver.lib.utils import process_list_in_batches
 from zerver.models import Reaction, RealmEmoji, Recipient, UserProfile
 
 
@@ -899,7 +900,7 @@ def map_receiver_id_to_recipient_id(
 def get_string_huddle_hash(id_list: List[str]) -> str:
     id_list = sorted(set(id_list))
     hash_key = ",".join(str(x) for x in id_list)
-    return make_safe_digest(hash_key)
+    return hashlib.sha1(hash_key.encode()).hexdigest()
 
 
 def categorize_channels_and_map_with_id(

zerver/lib/avatar_hash.py

@@ -2,7 +2,6 @@ import hashlib
 
 from django.conf import settings
 
-from zerver.lib.utils import make_safe_digest
 from zerver.models import UserProfile
 
 
@@ -13,7 +12,7 @@ def gravatar_hash(email: str) -> str:
     # outlining internationalization of email addresses, and regardless if we
     # typo an address or someone manages to give us a non-ASCII address, let's
     # not error out on it.
-    return make_safe_digest(email.lower(), hashlib.md5)
+    return hashlib.md5(email.lower().encode()).hexdigest()
 
 
 def user_avatar_hash(uid: str) -> str:
@@ -24,7 +23,7 @@ def user_avatar_hash(uid: str) -> str:
     # used a hash of the email address, not the user ID, and we salted
     # it in order to make the hashing scheme different from Gravatar's.
     user_key = uid + settings.AVATAR_SALT
-    return make_safe_digest(user_key, hashlib.sha1)
+    return hashlib.sha1(user_key.encode()).hexdigest()
 
 
 def user_avatar_path(user_profile: UserProfile) -> str:

zerver/lib/cache.py

@@ -30,8 +30,6 @@ from django.http import HttpRequest
 from django_stubs_ext import QuerySetAny
 from typing_extensions import ParamSpec
 
-from zerver.lib.utils import make_safe_digest
-
 if TYPE_CHECKING:
     # These modules have to be imported for type annotations but
     # they cannot be imported at runtime due to cyclic dependency.
@@ -190,7 +188,7 @@ def validate_cache_key(key: str) -> None:
     # and only "control" characters are strictly disallowed, see:
     # https://github.com/memcached/memcached/blob/master/doc/protocol.txt
     # However, limiting the characters we allow in keys simiplifies things,
-    # and anyway we use make_safe_digest when forming some keys to ensure
+    # and anyway we use a hash function when forming some keys to ensure
     # the resulting keys fit the regex below.
     # The regex checks "all characters between ! and ~ in the ascii table",
     # which happens to be the set of all "nice" ascii characters.
@@ -433,7 +431,7 @@ def bulk_cached_fetch(
 
 
 def preview_url_cache_key(url: str) -> str:
-    return f"preview_url:{make_safe_digest(url)}"
+    return f"preview_url:{hashlib.sha1(url.encode()).hexdigest()}"
 
 
 def display_recipient_cache_key(recipient_id: int) -> str:
@@ -447,7 +445,7 @@ def display_recipient_bulk_get_users_by_id_cache_key(user_id: int) -> str:
 
 
 def user_profile_cache_key_id(email: str, realm_id: int) -> str:
-    return f"user_profile:{make_safe_digest(email.strip())}:{realm_id}"
+    return f"user_profile:{hashlib.sha1(email.strip().encode()).hexdigest()}:{realm_id}"
 
 
 def user_profile_cache_key(email: str, realm: "Realm") -> str:
@@ -455,11 +453,11 @@ def user_profile_cache_key(email: str, realm: "Realm") -> str:
 
 
 def user_profile_delivery_email_cache_key(delivery_email: str, realm: "Realm") -> str:
-    return f"user_profile_by_delivery_email:{make_safe_digest(delivery_email.strip())}:{realm.id}"
+    return f"user_profile_by_delivery_email:{hashlib.sha1(delivery_email.strip().encode()).hexdigest()}:{realm.id}"
 
 
 def bot_profile_cache_key(email: str, realm_id: int) -> str:
-    return f"bot_profile:{make_safe_digest(email.strip())}"
+    return f"bot_profile:{hashlib.sha1(email.strip().encode()).hexdigest()}"
 
 
 def user_profile_by_id_cache_key(user_profile_id: int) -> str:
@@ -700,7 +698,9 @@ def to_dict_cache_key(message: "Message", realm_id: Optional[int] = None) -> str
 
 
 def open_graph_description_cache_key(content: bytes, request: HttpRequest) -> str:
-    return "open_graph_description_path:{}".format(make_safe_digest(request.META["PATH_INFO"]))
+    return "open_graph_description_path:{}".format(
+        hashlib.sha1(request.META["PATH_INFO"].encode()).hexdigest()
+    )
 
 
 def flush_message(*, instance: "Message", **kwargs: object) -> None:

zerver/lib/utils.py

@@ -1,23 +1,10 @@
-import hashlib
 import re
 import secrets
-from typing import TYPE_CHECKING, Callable, List, Optional, TypeVar
-
-if TYPE_CHECKING:
-    from hashlib import _Hash
+from typing import Callable, List, Optional, TypeVar
 
 T = TypeVar("T")
 
 
-def make_safe_digest(string: str, hash_func: "Callable[[bytes], _Hash]" = hashlib.sha1) -> str:
-    """
-    return a hex digest of `string`.
-    """
-    # hashlib.sha1, md5, etc. expect bytes, so non-ASCII strings must
-    # be encoded.
-    return hash_func(string.encode()).hexdigest()
-
-
 def generate_api_key() -> str:
     api_key = ""
     while len(api_key) < 32:

zerver/migrations/0032_verify_all_medium_avatar_images.py

@@ -7,7 +7,6 @@ from django.db.backends.base.schema import BaseDatabaseSchemaEditor
 from django.db.migrations.state import StateApps
 
 from zerver.lib.upload import upload_backend
-from zerver.lib.utils import make_safe_digest
 from zerver.models import UserProfile
 
 
@@ -20,7 +19,7 @@ from zerver.models import UserProfile
 def patched_user_avatar_path(user_profile: UserProfile) -> str:
     email = user_profile.email
     user_key = email.lower() + settings.AVATAR_SALT
-    return make_safe_digest(user_key, hashlib.sha1)
+    return hashlib.sha1(user_key.encode()).hexdigest()
 
 
 @patch("zerver.lib.upload.s3.user_avatar_path", patched_user_avatar_path)

zerver/models.py

@@ -1,5 +1,6 @@
 import ast
 import datetime
+import hashlib
 import secrets
 import time
 from contextlib import suppress
@@ -100,7 +101,7 @@ from zerver.lib.types import (
     UserFieldElement,
     Validator,
 )
-from zerver.lib.utils import generate_api_key, make_safe_digest
+from zerver.lib.utils import generate_api_key
 from zerver.lib.validator import (
     check_date,
     check_int,
@@ -2811,7 +2812,7 @@ def get_client(name: str) -> Client:
 
 
 def get_client_cache_key(name: str) -> str:
-    return f"get_client:{make_safe_digest(name)}"
+    return f"get_client:{hashlib.sha1(name.encode()).hexdigest()}"
 
 
 @cache_with_key(get_client_cache_key, timeout=3600 * 24 * 7)
@@ -4035,7 +4036,7 @@ class Huddle(models.Model):
 def get_huddle_hash(id_list: List[int]) -> str:
     id_list = sorted(set(id_list))
     hash_key = ",".join(str(x) for x in id_list)
-    return make_safe_digest(hash_key)
+    return hashlib.sha1(hash_key.encode()).hexdigest()
 
 
 def huddle_hash_cache_key(huddle_hash: str) -> str: