Added a convertor for hazmat-imported keys (currently only openssl ba…

…ckend).

securesystemslib/convert/__init__.py

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+

securesystemslib/convert/hazmat.py

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+"""
+This module contains functions to convert `cryptography.hazmat` keys into `securesystemlib` key dicts.
+"""
+
+
+import typing
+
+from cryptography.hazmat.backends.openssl.ec import (
+    _EllipticCurvePrivateKey,
+    _EllipticCurvePublicKey,
+)
+from cryptography.hazmat.backends.openssl.ed25519 import (
+    _Ed25519PrivateKey,
+    _Ed25519PublicKey,
+)
+from cryptography.hazmat.backends.openssl.rsa import (
+    _RSAPrivateKey,
+    _RSAPublicKey,
+)
+from cryptography.hazmat.primitives.serialization import (
+    Encoding,
+    NoEncryption,
+    PrivateFormat,
+    PublicFormat,
+)
+
+from ..keys import (
+    format_ed25519_dict,
+    import_ecdsakey_from_pem,
+    import_rsakey_from_pem,
+)
+
+
+def _hazmat_key_to_pem(
+    key: typing.Union[
+        _RSAPrivateKey,
+        _EllipticCurvePrivateKey,
+    ]
+) -> str:
+    """The approach already used in this lib is to convert keys into PEM and then to parse from it."""
+
+    if key.__class__.__name__.endswith("PrivateKey"):
+        serialized = key.private_bytes(
+            Encoding.PEM,
+            PrivateFormat.TraditionalOpenSSL,
+            NoEncryption(),
+        )
+    elif key.__class__.__name__.endswith("PublicKey"):
+        serialized = key.public_bytes(
+            Encoding.PEM,
+            PublicFormat.SubjectPublicKeyInfo,
+        )
+    else:
+        raise TypeError(key)
+
+    return serialized.decode("utf-8")
+
+
+def _import_hazmat_ed25519_private_key(
+    key: _Ed25519PrivateKey,
+) -> dict:
+    """Imports hazmat ed25519 private key"""
+
+    pub = key.public_key().public_bytes(
+        Encoding.Raw,
+        PublicFormat.Raw,
+    )
+    sec = key.private_bytes(
+        Encoding.Raw,
+        PrivateFormat.Raw,
+        NoEncryption(),
+    )
+    return format_ed25519_dict(
+        pub,
+        sec,
+    )
+
+
+def _import_hazmat_ed25519_public_key(
+    key: _Ed25519PublicKey,
+) -> dict:
+    """Imports hazmat ed25519 public key"""
+
+    pub = key.public_bytes(
+        Encoding.Raw,
+        PublicFormat.Raw,
+    )
+    return format_ed25519_dict(
+        pub,
+        None,
+    )
+
+
+def _import_rsa_key(
+    key: _RSAPrivateKey,
+) -> dict:
+    """Imports hazmat RSA key"""
+
+    return import_rsakey_from_pem(_hazmat_key_to_pem(key))
+
+
+def _import_ecdsa_key(
+    key: _EllipticCurvePrivateKey,
+) -> dict:
+    """Imports hazmat ECDSA key"""
+
+    return import_ecdsakey_from_pem(_hazmat_key_to_pem(key))
+
+
+_typeMapping = {
+    _Ed25519PrivateKey: _import_hazmat_ed25519_private_key,
+    _Ed25519PublicKey: _import_hazmat_ed25519_public_key,
+    _RSAPrivateKey: _import_rsa_key,
+    _RSAPublicKey: _import_rsa_key,
+    _EllipticCurvePrivateKey: _import_ecdsa_key,
+    _EllipticCurvePublicKey: _import_ecdsa_key,
+}
+
+
+def import_hazmat_key(
+    key: typing.Union[
+        _RSAPrivateKey, _EllipticCurvePrivateKey, _Ed25519PrivateKey
+    ]
+) -> dict:
+    """
+    <Purpose>
+        Converts a `cryptography.hazmat` key into a dictionary conformant to 'securesystemslib.formats.KEY_SCHEMA'.
+
+    <Arguments>
+        key:
+            A key of the classes from `cryptography.hazmat` module. Currently only keys of `openssl` backend are implemented.
+
+    <Exceptions>
+        securesystemslib.exceptions.FormatError, if 'key_value' does not conform to
+        'securesystemslib.formats.KEYVAL_SCHEMA', or if the private key is not
+        present in 'key_value' if requested by the caller via 'private'.
+        NotImplementedError, if we cannot convert a key of this type.
+
+    <Side Effects>
+        None.
+
+    <Returns>
+        A 'securesystemslib.formats.KEY_SCHEMA' dictionary."""
+
+    key_type = type(key)
+    try:
+        mapper = _typeMapping[key_type]
+    except KeyError as ex:
+        raise NotImplementedError(key_type) from ex
+    else:
+        return mapper(key)