Add checksum verification for portable backups

src/utils/__init__.py

@@ -14,7 +14,12 @@ try:
         EncryptionMode,
         DEFAULT_ENCRYPTION_MODE,
     )
-    from .checksum import calculate_checksum, verify_checksum
+    from .checksum import (
+        calculate_checksum,
+        verify_checksum,
+        json_checksum,
+        canonical_json_dumps,
+    )
     from .password_prompt import prompt_for_password
 
     if logger.isEnabledFor(logging.DEBUG):
@@ -31,6 +36,8 @@ __all__ = [
     "DEFAULT_ENCRYPTION_MODE",
     "calculate_checksum",
     "verify_checksum",
+    "json_checksum",
+    "canonical_json_dumps",
     "exclusive_lock",
     "shared_lock",
     "prompt_for_password",

src/utils/checksum.py

@@ -14,8 +14,9 @@ import hashlib
 import logging
 import sys
 import os
+import json
 import traceback
-from typing import Optional
+from typing import Optional, Any
 
 from termcolor import colored
 
@@ -25,6 +26,17 @@ from constants import APP_DIR, SCRIPT_CHECKSUM_FILE
 logger = logging.getLogger(__name__)
 
 
+def canonical_json_dumps(data: Any) -> str:
+    """Serialize ``data`` into a canonical JSON string."""
+    return json.dumps(data, sort_keys=True, separators=(",", ":"))
+
+
+def json_checksum(data: Any) -> str:
+    """Return SHA-256 checksum of canonical JSON serialization of ``data``."""
+    canon = canonical_json_dumps(data)
+    return hashlib.sha256(canon.encode("utf-8")).hexdigest()
+
+
 def calculate_checksum(file_path: str) -> Optional[str]:
     """
     Calculates the SHA-256 checksum of the given file.