diff --git a/scripts/mbedtls_dev/crypto_knowledge.py b/scripts/mbedtls_dev/crypto_knowledge.py
index 4b4e2df..01a8c5d 100644
--- a/scripts/mbedtls_dev/crypto_knowledge.py
+++ b/scripts/mbedtls_dev/crypto_knowledge.py
@@ -19,7 +19,7 @@
 # limitations under the License.
 
 import re
-from typing import Iterable, Optional, Tuple
+from typing import Iterable, Optional, Tuple, Dict
 
 from mbedtls_dev.asymmetric_key_data import ASYMMETRIC_KEY_DATA
 
@@ -138,3 +138,18 @@
             return des3[:length]
         return b''.join([self.DATA_BLOCK] * (length // len(self.DATA_BLOCK)) +
                         [self.DATA_BLOCK[:length % len(self.DATA_BLOCK)]])
+
+    KEY_TYPE_FOR_SIGNATURE = {
+        'PSA_KEY_USAGE_SIGN_HASH': '.*KEY_PAIR',
+        'PSA_KEY_USAGE_VERIFY_HASH': '.*KEY.*'
+    } #type: Dict[str, str]
+    """Use a regexp to determine key types for which signature is possible
+       when using the actual usage flag.
+    """
+    def is_valid_for_signature(self, usage: str) -> bool:
+        """Determine if the key type is compatible with the specified
+           signitute type.
+
+        """
+        # This is just temporaly solution for the implicit usage flags.
+        return re.match(self.KEY_TYPE_FOR_SIGNATURE[usage], self.name) is not None
diff --git a/scripts/mbedtls_dev/psa_storage.py b/scripts/mbedtls_dev/psa_storage.py
index 5ff1738..88992a6 100644
--- a/scripts/mbedtls_dev/psa_storage.py
+++ b/scripts/mbedtls_dev/psa_storage.py
@@ -107,14 +107,6 @@
     } #type: Dict[str, str]
     """Mapping of usage flags to the flags that they imply."""
 
-    IMPLICIT_USAGE_FLAGS_KEY_RESTRICTION = {
-        'PSA_KEY_USAGE_SIGN_HASH': '.*KEY_PAIR',
-        'PSA_KEY_USAGE_VERIFY_HASH': '.*KEY.*'
-    } #type: Dict[str, str]
-    """Use a regexp to determine key types for which signature is possible
-       when using the actual usage flag.
-    """
-
     def __init__(self, *,
                  version: Optional[int] = None,
                  id: Optional[int] = None, #pylint: disable=redefined-builtin