diff --git a/sros2/sros2/_utilities.py b/sros2/sros2/_utilities.py
index f35442f4..aaae0a8e 100644
--- a/sros2/sros2/_utilities.py
+++ b/sros2/sros2/_utilities.py
@@ -16,6 +16,7 @@
 import datetime
 import os
 import pathlib
+from zoneinfo import ZoneInfo
 
 from cryptography import x509
 from cryptography.hazmat.backends import default_backend as cryptography_backend
@@ -28,6 +29,9 @@
 _DOMAIN_ID_ENV = 'ROS_DOMAIN_ID'
 _KEYSTORE_DIR_ENV = 'ROS_SECURITY_KEYSTORE'
 
+def convert_naive_to_utc(naive_datetime: datetime.datetime) -> datetime.datetime:
+    return naive_datetime.replace(tzinfo=ZoneInfo('UTC'))
+
 
 def create_symlink(*, src: pathlib.Path, dst: pathlib.Path):
     if dst.exists():
@@ -80,7 +84,7 @@ def build_key_and_cert(subject_name, *, ca=False, ca_key=None, issuer_name=''):
     else:
         extension = x509.BasicConstraints(ca=False, path_length=None)
 
-    utcnow = datetime.datetime.utcnow()
+    utcnow = datetime.datetime.now(datetime.UTC)
     builder = x509.CertificateBuilder(
         ).issuer_name(
             issuer_name
@@ -90,7 +94,7 @@ def build_key_and_cert(subject_name, *, ca=False, ca_key=None, issuer_name=''):
             # Using a day earlier here to prevent Connext (5.3.1) from complaining
             # when extracting it from the permissions file and thinking it's in the future
             # https://github.com/ros2/ci/pull/436#issuecomment-624874296
-            utcnow - datetime.timedelta(days=1)
+            utcnow
         ).not_valid_after(
             # TODO: This should not be hard-coded
             utcnow + datetime.timedelta(days=3650)
diff --git a/sros2/sros2/keystore/_permission.py b/sros2/sros2/keystore/_permission.py
index 47c10bd8..929de6a7 100644
--- a/sros2/sros2/keystore/_permission.py
+++ b/sros2/sros2/keystore/_permission.py
@@ -75,8 +75,10 @@ def create_permission_file(path: pathlib.Path, domain_id, policy_element) -> Non
 
     cert_path = path.parent.joinpath('cert.pem')
     cert_content = _utilities.load_cert(cert_path)
-    kwargs['not_valid_before'] = etree.XSLT.strparam(cert_content.not_valid_before.isoformat())
-    kwargs['not_valid_after'] = etree.XSLT.strparam(cert_content.not_valid_after.isoformat())
+    # TODO replace not_valid_before/not_valid_after functions by not_valid_before_utc/not_valid_after_utc
+    # once cryptography 42 is supported on all target platforms
+    kwargs['not_valid_before'] = etree.XSLT.strparam(_utilities.convert_naive_to_utc(cert_content.not_valid_before).isoformat())
+    kwargs['not_valid_after'] = etree.XSLT.strparam(_utilities.convert_naive_to_utc(cert_content.not_valid_after).isoformat())
 
     if get_rmw_implementation_identifier() in _RMW_WITH_ROS_GRAPH_INFO_TOPIC:
         kwargs['allow_ros_discovery_topic'] = etree.XSLT.strparam('1')
diff --git a/sros2/test/sros2/commands/security/verbs/test_create_enclave.py b/sros2/test/sros2/commands/security/verbs/test_create_enclave.py
index bed0c740..4a02c93c 100644
--- a/sros2/test/sros2/commands/security/verbs/test_create_enclave.py
+++ b/sros2/test/sros2/commands/security/verbs/test_create_enclave.py
@@ -123,13 +123,15 @@ def test_cert_pem(enclave_keys_dir):
     assert isinstance(cert.signature_hash_algorithm, hashes.SHA256)
 
     # Verify the cert is valid for the expected timespan
-    utcnow = datetime.datetime.utcnow()
+    utcnow = datetime.datetime.now(datetime.UTC)
 
     # Using a day earlier here to prevent Connext (5.3.1) from complaining
     # when extracting it from the permissions file and thinking it's in the future
     # https://github.com/ros2/ci/pull/436#issuecomment-624874296
-    assert _datetimes_are_close(cert.not_valid_before, utcnow - datetime.timedelta(days=1))
-    assert _datetimes_are_close(cert.not_valid_after, utcnow + datetime.timedelta(days=3650))
+    # TODO replace not_valid_before/not_valid_after functions by not_valid_before_utc/not_valid_after_utc
+    # once cryptography 42 is supported on all target platforms
+    assert _datetimes_are_close(_utilities.convert_naive_to_utc(cert.not_valid_before), utcnow)
+    assert _datetimes_are_close(_utilities.convert_naive_to_utc(cert.not_valid_after), utcnow + datetime.timedelta(days=3650))
 
     # Verify that the cert ensures this key cannot be used to sign others as a CA
     assert len(cert.extensions) == 1