async def test_verify_signatures_manipulated_signatures(
gnupg_keypair: GnuPGKeypair, image_config: ImageConfig
):
"""Test that signature verification detects manipulated signatures."""
signer = GPGSigner(
keyid=gnupg_keypair.keyid,
passphrase=gnupg_keypair.passphrase,
homedir=gnupg_keypair.gnupg_home,
)
# Add a single signature ...
await image_config.sign(signer)
response = await image_config.verify_signatures(
signer_kwargs={GPGSigner.__name__: {"homedir": gnupg_keypair.gnupg_home}}
)
assert response.results[0].valid
# Modify the digest value of the (first) signature ...
signatures = image_config.get_signature_list()
temp = deepcopy(signatures)
temp[0] = ImageConfigSignatureEntry(
digest=FormattedSHA256.calculate(b"tampertampertamper"),
signature=temp[0].signature,
)
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(DigestMismatchError) as exception:
await 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)
await image_config.sign(signer, SignatureTypes.ENDORSE)
response = await image_config.verify_signatures(
signer_kwargs={GPGSigner.__name__: {"homedir": gnupg_keypair.gnupg_home}}
)
assert response.results[0].valid
# Modify the digest value of the second signature ...
signatures = image_config.get_signature_list()
temp = deepcopy(signatures)
temp[1] = ImageConfigSignatureEntry(
digest=FormattedSHA256.calculate(b"tampertampertamper"),
signature=temp[1].signature,
)
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(DigestMismatchError) as exception:
await image_config.verify_signatures()
assert str(exception.value).startswith("Image config canonical digest mismatch:")
async def test_verify_signatures_manipulated_signatures(image_config: ImageConfig):
"""Test that signature verification detects manipulated signatures."""
# Add a single signature ...
signer = FakeSigner()
assert await 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
response = await image_config.verify_signatures()
assert response["results"][0]["valid"] is True
# Modify the digest value of the (first) signature ...
signatures = image_config.get_signature_list()
temp = 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(DigestMismatchError) as exception:
await 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 (
await image_config.sign(signer, SignatureTypes.ENDORSE)
== signer.signature_value
)
# Sanity check
response = await image_config.verify_signatures()
assert response["results"][0]["valid"] is True
# Modify the digest value of the second signature ...
signatures = image_config.get_signature_list()
temp = 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(DigestMismatchError) as exception:
await image_config.verify_signatures()
assert str(exception.value).startswith("Image config canonical digest mismatch:")
# Restore the original class method
Signer.for_signature = original_method