mirror of
https://github.com/theupdateframework/python-tuf
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3d8cade471
Add sub-package with 3 abstract base classes to:
- serialize Metadata objects to bytes (transport)
- deserialize Metadata objects from bytes (transport)
- serialize Signed objects to bytes (signatures)
pylint notes:
- configure tox to use api/pylintrc
- configure api/pylintrc to allow classes without public methods
(default was 2)
Design considerations
---------------------
- Why not implement de/serialization on metadata classes?
-> See ADR0006.
- Why use separate classes for serialization and deserialization?
-> Some users might only need either one, e.g. client only needs
Deserializer. Maybe there are use cases where different
implementations are used to serialize and deserialize.
- Why use separate classes for Metadata- and Signed-Serialization?
-> They require different concrete types, i.e. Metadata and
Signed as parameters, and using these specific types seems to
make the interface stronger.
- Why are de/serialize methods not class/staticmethods?
-> In reality we only use classes to namespace and define a
type annotated interface, thus it would be enough to make the
methods classmethods. However, to keep the de/serialize
interface minimal, we move any custom format configuration to
the constructor. (See e.g. "compact" for JSONSerializer in
subsequent commit).
Naming considerations
---------------------
- Why de/serialize?
-> Implies byte stream as input or output to the function, which
is what our interface needs.
- Why not marshaling?
-> Synonym for serialize but implies transport, would be okay.
- Why not encoding?
-> Too abstract and too many connotations (character, a/v).
- Why not parse?
-> Too abstract and no good opposite terms (unparse, write,
dump?)
Signed-off-by: Lukas Puehringer <lukas.puehringer@nyu.edu>
43 lines
1.4 KiB
Python
43 lines
1.4 KiB
Python
"""TUF role metadata de/serialization.
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This sub-package provides abstract base classes and concrete implementations to
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serialize and deserialize TUF role metadata and metadata parts.
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Any custom de/serialization implementations should inherit from the abstract
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base classes defined in this __init__.py module.
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- Metadata de/serializers are used to convert to and from wireline formats.
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- Signed serializers are used to canonicalize data for cryptographic signatures
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generation and verification.
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"""
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import abc
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class MetadataDeserializer():
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"""Abstract base class for deserialization of Metadata objects. """
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__metaclass__ = abc.ABCMeta
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@abc.abstractmethod
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def deserialize(self, raw_data: bytes) -> "Metadata":
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"""Deserialize passed bytes to Metadata object. """
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raise NotImplementedError
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class MetadataSerializer():
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"""Abstract base class for serialization of Metadata objects. """
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__metaclass__ = abc.ABCMeta
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@abc.abstractmethod
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def serialize(self, metadata_obj: "Metadata") -> bytes:
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"""Serialize passed Metadata object to bytes. """
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raise NotImplementedError
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class SignedSerializer():
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"""Abstract base class for serialization of Signed objects. """
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__metaclass__ = abc.ABCMeta
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@abc.abstractmethod
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def serialize(self, signed_obj: "Signed") -> bytes:
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"""Serialize passed Signed object to bytes. """
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raise NotImplementedError
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