236 lines
7.2 KiB
Python
236 lines
7.2 KiB
Python
# This file is dual licensed under the terms of the Apache License, Version
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# 2.0, and the BSD License. See the LICENSE file in the root of this repository
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# for complete details.
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from __future__ import annotations
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import email.base64mime
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import email.generator
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import email.message
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import email.policy
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import io
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import typing
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from cryptography import utils, x509
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from cryptography.hazmat.bindings._rust import pkcs7 as rust_pkcs7
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from cryptography.hazmat.primitives import hashes, serialization
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from cryptography.hazmat.primitives.asymmetric import ec, rsa
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from cryptography.utils import _check_byteslike
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def load_pem_pkcs7_certificates(data: bytes) -> typing.List[x509.Certificate]:
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from cryptography.hazmat.backends.openssl.backend import backend
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return backend.load_pem_pkcs7_certificates(data)
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def load_der_pkcs7_certificates(data: bytes) -> typing.List[x509.Certificate]:
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from cryptography.hazmat.backends.openssl.backend import backend
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return backend.load_der_pkcs7_certificates(data)
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def serialize_certificates(
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certs: typing.List[x509.Certificate],
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encoding: serialization.Encoding,
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) -> bytes:
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return rust_pkcs7.serialize_certificates(certs, encoding)
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PKCS7HashTypes = typing.Union[
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hashes.SHA224,
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hashes.SHA256,
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hashes.SHA384,
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hashes.SHA512,
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]
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PKCS7PrivateKeyTypes = typing.Union[
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rsa.RSAPrivateKey, ec.EllipticCurvePrivateKey
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]
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class PKCS7Options(utils.Enum):
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Text = "Add text/plain MIME type"
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Binary = "Don't translate input data into canonical MIME format"
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DetachedSignature = "Don't embed data in the PKCS7 structure"
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NoCapabilities = "Don't embed SMIME capabilities"
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NoAttributes = "Don't embed authenticatedAttributes"
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NoCerts = "Don't embed signer certificate"
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class PKCS7SignatureBuilder:
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def __init__(
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self,
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data: typing.Optional[bytes] = None,
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signers: typing.List[
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typing.Tuple[
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x509.Certificate,
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PKCS7PrivateKeyTypes,
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PKCS7HashTypes,
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]
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] = [],
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additional_certs: typing.List[x509.Certificate] = [],
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):
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self._data = data
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self._signers = signers
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self._additional_certs = additional_certs
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def set_data(self, data: bytes) -> PKCS7SignatureBuilder:
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_check_byteslike("data", data)
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if self._data is not None:
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raise ValueError("data may only be set once")
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return PKCS7SignatureBuilder(data, self._signers)
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def add_signer(
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self,
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certificate: x509.Certificate,
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private_key: PKCS7PrivateKeyTypes,
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hash_algorithm: PKCS7HashTypes,
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) -> PKCS7SignatureBuilder:
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if not isinstance(
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hash_algorithm,
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(
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hashes.SHA224,
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hashes.SHA256,
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hashes.SHA384,
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hashes.SHA512,
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),
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):
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raise TypeError(
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"hash_algorithm must be one of hashes.SHA224, "
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"SHA256, SHA384, or SHA512"
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)
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if not isinstance(certificate, x509.Certificate):
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raise TypeError("certificate must be a x509.Certificate")
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if not isinstance(
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private_key, (rsa.RSAPrivateKey, ec.EllipticCurvePrivateKey)
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):
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raise TypeError("Only RSA & EC keys are supported at this time.")
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return PKCS7SignatureBuilder(
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self._data,
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self._signers + [(certificate, private_key, hash_algorithm)],
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)
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def add_certificate(
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self, certificate: x509.Certificate
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) -> PKCS7SignatureBuilder:
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if not isinstance(certificate, x509.Certificate):
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raise TypeError("certificate must be a x509.Certificate")
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return PKCS7SignatureBuilder(
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self._data, self._signers, self._additional_certs + [certificate]
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)
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def sign(
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self,
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encoding: serialization.Encoding,
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options: typing.Iterable[PKCS7Options],
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backend: typing.Any = None,
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) -> bytes:
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if len(self._signers) == 0:
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raise ValueError("Must have at least one signer")
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if self._data is None:
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raise ValueError("You must add data to sign")
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options = list(options)
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if not all(isinstance(x, PKCS7Options) for x in options):
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raise ValueError("options must be from the PKCS7Options enum")
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if encoding not in (
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serialization.Encoding.PEM,
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serialization.Encoding.DER,
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serialization.Encoding.SMIME,
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):
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raise ValueError(
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"Must be PEM, DER, or SMIME from the Encoding enum"
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)
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# Text is a meaningless option unless it is accompanied by
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# DetachedSignature
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if (
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PKCS7Options.Text in options
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and PKCS7Options.DetachedSignature not in options
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):
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raise ValueError(
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"When passing the Text option you must also pass "
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"DetachedSignature"
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)
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if PKCS7Options.Text in options and encoding in (
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serialization.Encoding.DER,
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serialization.Encoding.PEM,
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):
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raise ValueError(
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"The Text option is only available for SMIME serialization"
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)
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# No attributes implies no capabilities so we'll error if you try to
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# pass both.
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if (
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PKCS7Options.NoAttributes in options
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and PKCS7Options.NoCapabilities in options
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):
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raise ValueError(
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"NoAttributes is a superset of NoCapabilities. Do not pass "
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"both values."
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)
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return rust_pkcs7.sign_and_serialize(self, encoding, options)
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def _smime_encode(
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data: bytes, signature: bytes, micalg: str, text_mode: bool
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) -> bytes:
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# This function works pretty hard to replicate what OpenSSL does
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# precisely. For good and for ill.
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m = email.message.Message()
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m.add_header("MIME-Version", "1.0")
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m.add_header(
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"Content-Type",
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"multipart/signed",
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protocol="application/x-pkcs7-signature",
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micalg=micalg,
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)
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m.preamble = "This is an S/MIME signed message\n"
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msg_part = OpenSSLMimePart()
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msg_part.set_payload(data)
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if text_mode:
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msg_part.add_header("Content-Type", "text/plain")
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m.attach(msg_part)
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sig_part = email.message.MIMEPart()
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sig_part.add_header(
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"Content-Type", "application/x-pkcs7-signature", name="smime.p7s"
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)
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sig_part.add_header("Content-Transfer-Encoding", "base64")
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sig_part.add_header(
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"Content-Disposition", "attachment", filename="smime.p7s"
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)
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sig_part.set_payload(
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email.base64mime.body_encode(signature, maxlinelen=65)
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)
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del sig_part["MIME-Version"]
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m.attach(sig_part)
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fp = io.BytesIO()
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g = email.generator.BytesGenerator(
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fp,
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maxheaderlen=0,
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mangle_from_=False,
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policy=m.policy.clone(linesep="\r\n"),
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)
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g.flatten(m)
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return fp.getvalue()
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class OpenSSLMimePart(email.message.MIMEPart):
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# A MIMEPart subclass that replicates OpenSSL's behavior of not including
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# a newline if there are no headers.
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def _write_headers(self, generator) -> None:
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if list(self.raw_items()):
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generator._write_headers(self)
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