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# coding: utf-8
# -------------------------------------------------------------------------
# Copyright (c) Microsoft Corporation. All rights reserved.
# Licensed under the MIT License. See License.txt in the project root for
# license information.
# --------------------------------------------------------------------------
from time import time
import datetime
from cryptography import x509
from cryptography.hazmat.backends import default_backend
from cryptography.hazmat.primitives import hashes, serialization
from cryptography.hazmat.primitives.asymmetric import ec, rsa
from cryptography.x509 import (
BasicConstraints,
CertificateBuilder,
NameOID,
SubjectAlternativeName,
load_pem_x509_certificate,
)
import pytest
from azure.security.attestation import (
AttestationToken,
AttestationTokenValidationException,
)
class TestAzureAttestationToken(object):
def test_create_signing_key(self):
key = self._create_rsa_key()
cert = self._create_x509_certificate(key, u"test certificate")
certificate = load_pem_x509_certificate(
cert.encode("ascii"), backend=default_backend()
)
assert certificate.subject == x509.Name(
[x509.NameAttribute(NameOID.COMMON_NAME, u"test certificate")]
)
def test_create_signer_ecds(self):
"""Generate an ECDS key and a certificate wrapping the key, then verify we can create a signing key over it."""
eckey = self._create_ecds_key()
certificate = self._create_x509_certificate(eckey, u"attestation.test")
certificate = load_pem_x509_certificate(
certificate.encode("ascii"), backend=default_backend()
)
assert certificate.subject == x509.Name(
[x509.NameAttribute(NameOID.COMMON_NAME, u"attestation.test")]
)
def test_create_unsecured_token(self):
token = AttestationToken(body={"val1": [1, 2, 3]})
assert token._get_body() == {"val1": [1, 2, 3]}
def test_create_unsecured_empty_token(self):
token = AttestationToken(body=None)
assert token._get_body() is None
token._validate_token()
def test_create_secured_token(self):
key = self._create_rsa_key()
cert = self._create_x509_certificate(key, u"test certificate")
token = AttestationToken(
body={"val1": [1, 2, 3]}, signing_key=key, signing_certificate=cert
)
assert token._get_body() == {"val1": [1, 2, 3]}
token._validate_token()
def test_create_secured_empty_token(self):
key = self._create_rsa_key()
cert = self._create_x509_certificate(key, u"test certificate")
token = AttestationToken(body=None, signing_key=key, signing_certificate=cert)
assert token._get_body() is None
token._validate_token()
def test_token_callback(self):
key = self._create_rsa_key()
cert = self._create_x509_certificate(key, u"test certificate")
token = AttestationToken(
body={"val1": [1, 2, 3]}, signing_key=key, signing_certificate=cert
)
assert token._get_body() == {"val1": [1, 2, 3]}
global callback_invoked
callback_invoked = False
def callback(token, signer):
global callback_invoked
callback_invoked = True
assert signer.certificates[0] == cert
token._validate_token(validation_callback=callback)
assert callback_invoked
def test_token_callback_rejected(self):
key = self._create_rsa_key()
cert = self._create_x509_certificate(key, u"test certificate")
token = AttestationToken(
body={"val1": [1, 2, 3]}, signing_key=key, signing_certificate=cert
)
assert token._get_body() == {"val1": [1, 2, 3]}
global callback_invoked
callback_invoked = False
def callback(token, signer):
assert signer.certificates[0] == cert
raise ValueError("Validation failed.")
with pytest.raises(ValueError):
token._validate_token(validation_callback=callback)
# Verify that the token expiration checks work correctly.
def test_token_expiration(self):
token30sec = AttestationToken(
body={
"exp": time() + 30, # Expires in 30 seconds
"iat": time(),
"nbf": time(), # Not valid before now.
}
)
token30sec._validate_token()
expired_token = AttestationToken(
body={
"exp": time() - 30, # Expired 30 seconds ago
"iat": time(),
"nbf": time() + 5, # Not valid for 5 seconds.
}
)
with pytest.raises(AttestationTokenValidationException):
expired_token._validate_token()
early_token = AttestationToken(
body={
"exp": time() + 30, # Expires in 30 seconds
"iat": time(),
"nbf": time() + 5, # Not valid for 5 seconds.
}
)
with pytest.raises(AttestationTokenValidationException):
early_token._validate_token()
# Specify 40 seconds of slack, so we're within the slack.
# Token validation should start succeeding now because the slack
# lets it work.
expired_token._validate_token(validation_slack=40)
early_token._validate_token(validation_slack=40)
# Helper functions to create keys and certificates wrapping those keys.
@staticmethod
def _create_ecds_key(): # type: () -> str
return (
ec.generate_private_key(ec.SECP256R1(), backend=default_backend())
.private_bytes(
serialization.Encoding.PEM,
serialization.PrivateFormat.PKCS8,
serialization.NoEncryption(),
)
.decode("ascii")
)
@staticmethod
def _create_rsa_key(): # type: () -> str
return (
rsa.generate_private_key(65537, 2048, backend=default_backend())
.private_bytes(
serialization.Encoding.PEM,
serialization.PrivateFormat.PKCS8,
serialization.NoEncryption(),
)
.decode("ascii")
)
@staticmethod
def _create_x509_certificate(key_pem, subject_name): # type: (str, str) -> str
signing_key = serialization.load_pem_private_key(
key_pem.encode("utf-8"), password=None, backend=default_backend()
)
builder = CertificateBuilder()
builder = builder.subject_name(
x509.Name(
[
x509.NameAttribute(NameOID.COMMON_NAME, subject_name),
]
)
)
builder = builder.issuer_name(
x509.Name(
[
x509.NameAttribute(NameOID.COMMON_NAME, subject_name),
]
)
)
one_day = datetime.timedelta(1, 0, 0)
builder = builder.not_valid_before(datetime.datetime.today() - one_day)
builder = builder.not_valid_after(datetime.datetime.today() + (one_day * 30))
builder = builder.serial_number(x509.random_serial_number())
builder = builder.public_key(signing_key.public_key())
builder = builder.add_extension(
SubjectAlternativeName([x509.DNSName(subject_name)]), critical=False
)
builder = builder.add_extension(
BasicConstraints(ca=False, path_length=None), critical=True
)
return (
builder.sign(
private_key=signing_key,
algorithm=hashes.SHA256(),
backend=default_backend(),
)
.public_bytes(serialization.Encoding.PEM)
.decode("ascii")
)
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