diff --git a/common/tools.py b/common/tools.py
new file mode 100644
index 0000000..d89bbdf
--- /dev/null
+++ b/common/tools.py
@@ -0,0 +1,5 @@
+import re
+
+
+def check_sha256_hex_format(value):
+    return isinstance(value, str) and re.search(r"^[0-9A-Fa-f]{64}$", value) is not None