Unverified Commit f5857743 authored by illia-v's avatar illia-v
Browse files

Start using the cryptography package for verifying Ed25519 signatures

parent 9b189757

docs/faq.rst

+1 −3
Original line number Diff line number Diff line
@@ -53,8 +53,7 @@ Does Stem have any dependencies? 
**No.** All you need in order to use Stem is Python.



When it is available Stem will use `cryptography

<https://pypi.python.org/pypi/cryptography>`_ and `PyNaCl

<https://pypi.python.org/pypi/PyNaCl/>`_ to validate descriptor signatures.

<https://pypi.python.org/pypi/cryptography>`_ to validate descriptor signatures.

However, there is no need to install cryptography unless you need this

functionality.
@@ -81,7 +80,6 @@ Ubuntu you can install these with... 


  % sudo apt-get install python-dev libffi-dev

  % sudo pip install cryptography

  % sudo pip install pynacl



.. _what_python_versions_is_stem_compatible_with:

requirements.txt

+0 −1
Original line number Diff line number Diff line
@@ -3,4 +3,3 @@ pyflakes 
pycodestyle

tox

cryptography
 
pynacl

run_tests.py

+0 −1
Original line number Diff line number Diff line
@@ -163,7 +163,6 @@ def main(): 
    test.task.PYTHON_VERSION,

    test.task.PLATFORM_VERSION,

    test.task.CRYPTO_VERSION,

    test.task.PYNACL_VERSION,

    test.task.MOCK_VERSION,

    test.task.PYFLAKES_VERSION,

    test.task.PYCODESTYLE_VERSION,

stem/descriptor/certificate.py

+14 −15
Original line number Diff line number Diff line
@@ -224,34 +224,33 @@ class Ed25519CertificateV1(Ed25519Certificate): 


    :raises:

      * **ValueError** if signing key or descriptor are invalid

      * **ImportError** if pynacl module is unavailable

      * **ImportError** if cryptography module is unavailable or ed25519 is not supported

    """



    if not stem.prereq._is_pynacl_available():

      raise ImportError('Certificate validation requires the pynacl module')

    if not stem.prereq._is_crypto_ed25519_supported():

      raise ImportError('Certificate validation requires the cryptography module and support of ed25519')



    import nacl.signing

    import nacl.encoding

    from nacl.exceptions import BadSignatureError

    from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PublicKey

    from cryptography.exceptions import InvalidSignature



    descriptor_content = server_descriptor.get_bytes()

    signing_key = None



    if server_descriptor.ed25519_master_key:

      signing_key = nacl.signing.VerifyKey(stem.util.str_tools._to_bytes(server_descriptor.ed25519_master_key) + b'=', encoder = nacl.encoding.Base64Encoder)

      signing_key = Ed25519PublicKey.from_public_bytes(base64.b64decode(stem.util.str_tools._to_bytes(server_descriptor.ed25519_master_key) + b'='))

    else:

      for extension in self.extensions:

        if extension.type == ExtensionType.HAS_SIGNING_KEY:

          signing_key = nacl.signing.VerifyKey(extension.data)

          signing_key = Ed25519PublicKey.from_public_bytes(extension.data)

          break



    if not signing_key:

      raise ValueError('Server descriptor missing an ed25519 signing key')



    try:

      signing_key.verify(base64.b64decode(stem.util.str_tools._to_bytes(self.encoded))[:-ED25519_SIGNATURE_LENGTH], self.signature)

    except BadSignatureError as exc:

      raise ValueError('Ed25519KeyCertificate signing key is invalid (%s)' % exc)

      signing_key.verify(self.signature, base64.b64decode(stem.util.str_tools._to_bytes(self.encoded))[:-ED25519_SIGNATURE_LENGTH])

    except InvalidSignature:

      raise ValueError('Ed25519KeyCertificate signing key is invalid (Signature was forged or corrupt)')



    # ed25519 signature validates descriptor content up until the signature itself
@@ -265,7 +264,7 @@ class Ed25519CertificateV1(Ed25519Certificate): 
    signature_bytes = base64.b64decode(stem.util.str_tools._to_bytes(server_descriptor.ed25519_signature) + b'=' * missing_padding)



    try:

      verify_key = nacl.signing.VerifyKey(self.key)

      verify_key.verify(descriptor_sha256_digest, signature_bytes)

    except BadSignatureError as exc:

      raise ValueError('Descriptor Ed25519 certificate signature invalid (%s)' % exc)
 
      verify_key = Ed25519PublicKey.from_public_bytes(self.key)

      verify_key.verify(signature_bytes, descriptor_sha256_digest)

    except InvalidSignature:

      raise ValueError('Descriptor Ed25519 certificate signature invalid (Signature was forged or corrupt)')

stem/descriptor/server_descriptor.py

+1 −1
Original line number Diff line number Diff line
@@ -865,7 +865,7 @@ class RelayDescriptor(ServerDescriptor): 
          if onion_key_crosscert_digest != self._onion_key_crosscert_digest():

            raise ValueError('Decrypted onion-key-crosscert digest does not match local digest (calculated: %s, local: %s)' % (onion_key_crosscert_digest, self._onion_key_crosscert_digest()))



      if stem.prereq._is_pynacl_available() and self.certificate:

      if stem.prereq._is_crypto_ed25519_supported() and self.certificate:

        self.certificate.validate(self)



  @classmethod