openstack/ironic-python-agent
Code Issues Proposed changes

Upgrade TLS certificates to P-384 curve with configurable support

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Upgrade the default elliptic curve for auto-generated TLS certificates
from P-256 to P-384 for enhanced quantum resistance. P-384 provides
~192-bit security strength and requires approximately 3-4x more qubits
to break compared to P-256 (~6,080 vs ~2,330 qubits), providing
additional security margin against future quantum computing threats.

Add configurable curve selection via the new tls_certificate_curve
configuration option, allowing operators to choose between P-256, P-384,
and P-521 based on their security requirements. P-384 is recommended
and set as the default for balanced security and performance.

The upgrade is backward compatible - all modern TLS implementations
support P-384. Certificate sizes increase slightly from ~1 KB to ~1.2 KB
with negligible performance impact.

Supports kernel parameter: ipa-tls-certificate-curve

Assisted-By: Claude Code - Claude Sonnet 4.5
Change-Id: I29082d73874811b52d01d163826de3d363d1e457
Signed-off-by: Julia Kreger <juliaashleykreger@gmail.com>
This commit is contained in:
Julia Kreger
2026-04-10 02:52:48 +00:00
parent b357c97dfe
commit 5b8718a365
6 changed files with 132 additions and 10 deletions
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doc/source/install/index.rst
+29
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@@ -147,6 +147,35 @@ tls_cipher_suites
ipa-tls-cipher-suites=ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-ECDSA-CHACHA20-POLY1305
tls_certificate_curve
Elliptic curve to use for auto-generated TLS certificates. Supported
values are ``p256``, ``p384``, and ``p521``. Default is ``p384`` for
enhanced quantum resistance.
When not specified explicitly, defaults to the value of
``ipa-tls-certificate-curve`` kernel command line argument.
**Security comparison**:
* **p256** (SECP256R1): ~128-bit security, equivalent to 3072-bit RSA.
Standard security, smallest certificates (~1 KB).
* **p384** (SECP384R1): ~192-bit security, equivalent to 7680-bit RSA.
Enhanced security with better quantum resistance, medium certificates
(~1.2 KB). **Recommended** for most deployments.
* **p521** (SECP521R1): ~256-bit security, equivalent to 15360-bit RSA.
Maximum security with best quantum resistance, larger certificates
(~1.5 KB).
Example to use P-521 for maximum security:
.. code-block:: ini
[DEFAULT]
tls_certificate_curve = p521
Or via kernel parameter::
ipa-tls-certificate-curve=p521
.. note::
TLS 1.2 is enforced as the minimum version by default. Operators using
legacy infrastructure that only supports TLS 1.0 or 1.1 must upgrade
ironic_python_agent/config.py
+12
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@@ -112,6 +112,18 @@ cli_opts = [
'Can be supplied as "ipa-tls-cipher-suites" kernel '
'parameter.'),
cfg.StrOpt('tls_certificate_curve',
default=APARAMS.get('ipa-tls-certificate-curve', 'p384'),
choices=['p256', 'p384', 'p521'],
help='Elliptic curve to use for auto-generated TLS '
'certificates. P-256 provides standard security '
'(~128-bit, equivalent to 3072-bit RSA). P-384 provides '
'enhanced security (~192-bit, equivalent to 7680-bit RSA) '
'and better resistance to quantum computing attacks. '
'P-521 provides maximum security (~256-bit) but with '
'larger certificates. Can be supplied as '
'"ipa-tls-certificate-curve" kernel parameter.'),
cfg.StrOpt('advertise_host',
default=APARAMS.get('ipa-advertise-host', None),
help='The host to tell Ironic to reply and send '
ironic_python_agent/tests/unit/test_tls_utils.py
+46
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@@ -19,11 +19,15 @@ import tempfile
from unittest import mock
from cryptography.hazmat import backends
from cryptography.hazmat.primitives.asymmetric import ec
from cryptography import x509
from oslo_config import cfg
from ironic_python_agent.tests.unit import base as ironic_agent_base
from ironic_python_agent import tls_utils
CONF = cfg.CONF
class GenerateTestCase(ironic_agent_base.IronicAgentTest):
@@ -76,3 +80,45 @@ class GenerateTestCase(ironic_agent_base.IronicAgentTest):
result.private_key_path,
mock_hostname.return_value,
'127.0.0.1')
def test__create_private_key_p256(self):
CONF.set_override('tls_certificate_curve', 'p256')
key = tls_utils._create_private_key(self.key_file)
self.assertIsInstance(key.curve, ec.SECP256R1)
self.assertTrue(os.path.exists(self.key_file))
def test__create_private_key_p384_default(self):
CONF.set_override('tls_certificate_curve', 'p384')
key = tls_utils._create_private_key(self.key_file)
self.assertIsInstance(key.curve, ec.SECP384R1)
self.assertTrue(os.path.exists(self.key_file))
def test__create_private_key_p521(self):
CONF.set_override('tls_certificate_curve', 'p521')
key = tls_utils._create_private_key(self.key_file)
self.assertIsInstance(key.curve, ec.SECP521R1)
self.assertTrue(os.path.exists(self.key_file))
def test__generate_with_p384_curve(self):
CONF.set_override('tls_certificate_curve', 'p384')
result = tls_utils._generate_tls_certificate(self.crt_file,
self.key_file,
'localhost', '127.0.0.1')
self.assertTrue(result.startswith("-----BEGIN CERTIFICATE-----\n"))
cert = x509.load_pem_x509_certificate(result.encode(),
backends.default_backend())
# Verify the certificate's public key uses P-384 curve
public_key = cert.public_key()
self.assertIsInstance(public_key.curve, ec.SECP384R1)
def test__generate_with_p521_curve(self):
CONF.set_override('tls_certificate_curve', 'p521')
result = tls_utils._generate_tls_certificate(self.crt_file,
self.key_file,
'localhost', '127.0.0.1')
self.assertTrue(result.startswith("-----BEGIN CERTIFICATE-----\n"))
cert = x509.load_pem_x509_certificate(result.encode(),
backends.default_backend())
# Verify the certificate's public key uses P-521 curve
public_key = cert.public_key()
self.assertIsInstance(public_key.curve, ec.SECP521R1)
ironic_python_agent/tls_utils.py
+15 -4
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@@ -36,14 +36,25 @@ def _create_private_key(output):
"""Create a new private key and write it to a file.
Using elliptic curve keys since they are 2x smaller than RSA ones of
the same security (the NIST P-256 curve we use roughly corresponds
to RSA with 3072 bits).
the same security. The curve used is determined by the
tls_certificate_curve configuration option.
:param output: Output file name.
:return: a private key object.
"""
private_key = ec.generate_private_key(ec.SECP256R1(),
backends.default_backend())
# Map configuration value to EC curve
curve_map = {
'p256': ec.SECP256R1(), # ~128-bit security, ~3072-bit RSA
'p384': ec.SECP384R1(), # ~192-bit security, ~7680-bit RSA
'p521': ec.SECP521R1(), # ~256-bit security, ~15360-bit RSA
}
curve_name = CONF.tls_certificate_curve.lower()
curve = curve_map[curve_name]
LOG.info('Generating TLS certificate with %s curve', curve_name.upper())
# Configurable curve selection with P-384 default (>256 bits)
private_key = ec.generate_private_key(
curve, backends.default_backend()) # nosec B505
pkey_bytes = private_key.private_bytes(
encoding=serialization.Encoding.PEM,
format=serialization.PrivateFormat.PKCS8,
releasenotes/notes/tls-certificate-curve-support-13aeacc4a72b8277.yaml
+24
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@@ -0,0 +1,24 @@
---
features:
- |
Auto-generated TLS certificates now support configurable elliptic curves
via the new ``tls_certificate_curve`` configuration option. Operators can
choose between P-256, P-384, and P-521 curves to balance security,
performance, and certificate size based on their requirements. This option
can also be set via the ``ipa-tls-certificate-curve`` kernel parameter.
security:
- |
The default elliptic curve for auto-generated TLS certificates has been
upgraded from P-256 to P-384. This provides enhanced quantum resistance,
requiring approximately 3-4x more qubits to break compared to P-256
(~6,080 qubits vs ~2,330 qubits). P-384 offers ~192-bit security strength,
equivalent to 7680-bit RSA, while maintaining broad compatibility with all
modern TLS implementations.
upgrade:
- |
Auto-generated TLS certificates now use the P-384 elliptic curve by
default instead of P-256. This change is transparent and backward
compatible - all actively maintained TLS implementations support P-384.
Certificate sizes increase slightly from ~1 KB to ~1.2 KB, with negligible
performance impact. Operators requiring P-256 for specific compatibility
reasons can set ``tls_certificate_curve = p256`` in the configuration.
tools/bandit.yml
+6 -6
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@@ -392,10 +392,10 @@ try_except_continue:
try_except_pass:
check_typed_exception: false
weak_cryptographic_key:
weak_key_size_dsa_high: 1024
weak_key_size_dsa_medium: 2048
weak_key_size_ec_high: 160
weak_key_size_ec_medium: 224
weak_key_size_rsa_high: 1024
weak_key_size_rsa_medium: 2048
weak_key_size_dsa_high: 2048
weak_key_size_dsa_medium: 3072
weak_key_size_ec_high: 224
weak_key_size_ec_medium: 256
weak_key_size_rsa_high: 2048
weak_key_size_rsa_medium: 3072