Security: Insecure PIN Hashing (Unsalted SHA-256) #20
Description
File: app/api/auth.py
Lines: 19-20 (in _hash_pin)
Description:
The authentication PIN is currently hashed using a fast, unsalted SHA-256 algorithm:
def _hash_pin(pin: str) -> str:
return hashlib.sha256(pin.encode()).hexdigest()Since users are likely using 4-6 digit numeric PINs, this can be trivially broken using precomputed rainbow tables or brute-force dictionaries in milliseconds.
Impact:
If the SQLite database is leaked or accessed by an unauthorized entity, they can reverse all user PINs instantaneously.
Suggested Fix:
Migrate to a standard key derivation function such as bcrypt or argon2 using a library like passlib or Python's native hashlib.scrypt/hashlib.pbkdf2_hmac with a secure random salt.
# Example using passlib
from passlib.context import CryptContext
pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
def _hash_pin(pin: str) -> str:
return pwd_context.hash(pin)