fix(security): resolve code scanning alerts in JWT and checksum handling (#309)

* fix(security): resolve code scanning alerts in JWT and checksum handling

Author: BartoszBlizniak

cloudsmith_cli/core/credentials/oidc/cache.py

@@ -41,15 +41,16 @@ def _cache_key(api_host: str, org: str, service_slug: str) -> str:
 
 
 def _decode_jwt_exp(token: str) -> float | None:
-    """Decode the exp claim from a JWT without verification."""
+    """Read the exp claim from a JWT payload.
+
+    The token is only inspected to determine a cache TTL; it is never used to
+    make an authorization decision, so the signature is deliberately not
+    verified (the API rejects tampered tokens regardless).
+    """
     try:
         import jwt
 
-        payload = jwt.decode(
-            token,
-            options={"verify_signature": False},
-            algorithms=["RS256", "ES256", "HS256"],
-        )
+        payload = jwt.decode(token, options={"verify_signature": False})
         exp = payload.get("exp")
         if exp is not None:
             return float(exp)

cloudsmith_cli/core/download.py

@@ -583,7 +583,7 @@ def _verify_checksum(filepath: str, expected: str) -> bool:
 
         # Try SHA1
         if len(expected) == 40:
-            sha1_hash = hashlib.sha1()
+            sha1_hash = hashlib.sha1(usedforsecurity=False)
             with open(filepath, "rb") as f:
                 for chunk in iter(lambda: f.read(4096), b""):
                     sha1_hash.update(chunk)

cloudsmith_cli/core/utils.py

@@ -35,7 +35,7 @@ def read_file(*path):
 
 def calculate_file_md5(filepath, blocksize=2**20):
     """Calculate an MD5 hash for a file."""
-    checksum = hashlib.md5()
+    checksum = hashlib.md5(usedforsecurity=False)
 
     with click.open_file(filepath, "rb") as f: