diff --git a/scripts/mbedtls_dev/crypto_knowledge.py b/scripts/mbedtls_dev/crypto_knowledge.py
index 1bd011f..82487d9 100644
--- a/scripts/mbedtls_dev/crypto_knowledge.py
+++ b/scripts/mbedtls_dev/crypto_knowledge.py
@@ -20,7 +20,7 @@
 
 import enum
 import re
-from typing import Dict, Iterable, Optional, Pattern, Tuple
+from typing import Iterable, Optional, Tuple
 
 from mbedtls_dev.asymmetric_key_data import ASYMMETRIC_KEY_DATA
 
@@ -178,21 +178,6 @@
         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': re.compile('.*KEY_PAIR'),
-        'PSA_KEY_USAGE_VERIFY_HASH': re.compile('.*KEY.*')
-    } #type: Dict[str, Pattern]
-    """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
-
     def can_do(self, alg: 'Algorithm') -> bool:
         """Whether this key type can be used for operations with the given algorithm.
 
diff --git a/tests/scripts/generate_psa_tests.py b/tests/scripts/generate_psa_tests.py
index ca94d7d..d25af22 100755
--- a/tests/scripts/generate_psa_tests.py
+++ b/tests/scripts/generate_psa_tests.py
@@ -206,7 +206,7 @@
                 continue
                 # For public key we expect that key generation fails with
                 # INVALID_ARGUMENT. It is handled by KeyGenerate class.
-            if not kt.name.endswith('_PUBLIC_KEY'):
+            if not kt.is_public():
                 yield test_case_for_key_type_not_supported(
                     'generate', kt.expression, bits,
                     finish_family_dependencies(generate_dependencies, bits),
@@ -822,8 +822,10 @@
                 for key_type in sorted(alg_with_keys[alg]):
                     # The key types must be filtered to fit the specific usage flag.
                     kt = crypto_knowledge.KeyType(key_type)
-                    if kt.is_valid_for_signature(usage):
-                        yield self.keys_for_implicit_usage(usage, alg, kt)
+                    if kt.is_public() and '_SIGN_' in usage:
+                        # Can't sign with a public key
+                        continue
+                    yield self.keys_for_implicit_usage(usage, alg, kt)
 
     def generate_all_keys(self) -> Iterator[StorageTestData]:
         yield from super().generate_all_keys()