def test_verify_signatures(image_config: ImageConfig):
"""Test signature verification for signed and unsigned configurations."""
# Unsigned configurations should explicitly raise an exception.
with pytest.raises(Exception) as e:
image_config.verify_signatures()
assert str(e.value) == "Image does not contain any signatures!"
# Sign a previously unsigned configuration, so that only the new signature type is present.
# Note: It is not trivial to embed "known" GPG / PKI signature types, as assumptions about the
# test environment are difficult to make.
image_config.sign(FakeSigner())
# An exception should be raised if the provider for a signature type is not known
with pytest.raises(Exception) as e:
image_config.verify_signatures()
assert str(e.value) == "Unsupported signature type!"
# Replace the class method for resolving signature providers ...
original_method = Signer.for_signature
Signer.for_signature = _signer_for_signature
# The Signer's verify() method should be invoked.
assert image_config.verify_signatures()["results"] == [{
"type": "fake",
"valid": True
}]
# Restore the original class method
Signer.for_signature = original_method
def test_verify_signatures_manipulated_signatures(image_config: ImageConfig):
"""Test that signature verification detects manipulated signatures."""
# Add a single signature ...
signer = FakeSigner()
assert image_config.sign(signer) == signer.signature_value
# Replace the class method for resolving signature providers ...
original_method = Signer.for_signature
Signer.for_signature = _signer_for_signature
# Sanity check
assert image_config.verify_signatures()["results"][0]["valid"] is True
# Modify the digest value of the (first) signature ...
signatures = image_config.get_signature_list()
temp = copy.deepcopy(signatures)
temp[0]["digest"] = "tampertampertamper"
image_config.set_signature_list(temp)
# An exception should be raised if digest value from the signature does not match the canonical digest of the image
# configuration (without any signatures).
with pytest.raises(Exception) as exception:
image_config.verify_signatures()
assert str(
exception.value).startswith("Image config canonical digest mismatch:")
# Restore the unmodified signature and endorse ...
image_config.set_signature_list(signatures)
assert image_config.sign(signer,
SignatureTypes.ENDORSE) == signer.signature_value
# Sanity check
assert image_config.verify_signatures()["results"][0]["valid"] is True
# Modify the digest value of the second signature ...
signatures = image_config.get_signature_list()
temp = copy.deepcopy(signatures)
temp[1]["digest"] = "tampertampertamper"
image_config.set_signature_list(temp)
# An exception should be raised if digest value from the signature does not match the canonical digest of the image
# configuration (including the first signature).
with pytest.raises(Exception) as exception:
image_config.verify_signatures()
assert str(
exception.value).startswith("Image config canonical digest mismatch:")
# Restore the original class method
Signer.for_signature = original_method