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Fix possible timing leak in validate_password #1535

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Merged
prandla merged 1 commit into from
Aug 27, 2025
Merged

Fix possible timing leak in validate_password #1535

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9 changes: 5 additions & 4 deletions cmscommon/crypto.py
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,7 @@
"""Utilities dealing with encryption and randomness."""

import binascii
import hmac
import random
from string import ascii_lowercase

Expand Down Expand Up @@ -190,15 +191,15 @@ def validate_password(authentication: str, password: str) -> bool:

"""
method, payload = parse_authentication(authentication)
password_bytes = password.encode("utf-8")
payload_bytes = payload.encode("utf-8")
if method == "bcrypt":
password_bytes = password.encode("utf-8")
payload_bytes = payload.encode("utf-8")
try:
return bcrypt.hashpw(password_bytes, payload_bytes) == payload_bytes
return bcrypt.checkpw(password_bytes, payload_bytes)
except ValueError:
return False
elif method == "plaintext":
return payload == password
return hmac.compare_digest(password_bytes, payload_bytes)
else:
raise ValueError("Authentication method not known.")

Expand Down