修改为东南天坐标系

backend_service/venv/lib/python3.13/site-packages/google/auth/_agent_identity_utils.py

@@ -0,0 +1,281 @@
+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Helpers for Agent Identity credentials."""
+
+import base64
+import hashlib
+import logging
+import os
+import re
+import time
+from urllib.parse import quote, urlparse
+
+from google.auth import environment_vars
+from google.auth import exceptions
+from google.auth.transport import _mtls_helper
+
+
+_LOGGER = logging.getLogger(__name__)
+
+CRYPTOGRAPHY_NOT_FOUND_ERROR = (
+    "The cryptography library is required for certificate-based authentication."
+    "Please install it with `pip install google-auth[cryptography]`."
+)
+
+# SPIFFE trust domain patterns for Agent Identities.
+_AGENT_IDENTITY_SPIFFE_TRUST_DOMAIN_PATTERNS = [
+    r"^agents\.global\.org-\d+\.system\.id\.goog$",
+    r"^agents\.global\.proj-\d+\.system\.id\.goog$",
+]
+
+_WELL_KNOWN_CERT_PATH = "/var/run/secrets/workload-spiffe-credentials/certificates.pem"
+
+# Constants for polling the certificate file.
+_FAST_POLL_CYCLES = 50
+_FAST_POLL_INTERVAL = 0.1  # 100ms
+_SLOW_POLL_INTERVAL = 0.5  # 500ms
+_TOTAL_TIMEOUT = 30  # seconds
+
+# Calculate the number of slow poll cycles based on the total timeout.
+_SLOW_POLL_CYCLES = int(
+    (_TOTAL_TIMEOUT - (_FAST_POLL_CYCLES * _FAST_POLL_INTERVAL)) / _SLOW_POLL_INTERVAL
+)
+
+_POLLING_INTERVALS = ([_FAST_POLL_INTERVAL] * _FAST_POLL_CYCLES) + (
+    [_SLOW_POLL_INTERVAL] * _SLOW_POLL_CYCLES
+)
+
+
+def _is_certificate_file_ready(path):
+    """Checks if a file exists and is not empty."""
+    return path and os.path.exists(path) and os.path.getsize(path) > 0
+
+
+def get_agent_identity_certificate_path():
+    """Gets the certificate path from the certificate config file.
+
+    The path to the certificate config file is read from the
+    GOOGLE_API_CERTIFICATE_CONFIG environment variable. This function
+    implements a retry mechanism to handle cases where the environment
+    variable is set before the files are available on the filesystem.
+
+    Returns:
+        str: The path to the leaf certificate file.
+
+    Raises:
+        google.auth.exceptions.RefreshError: If the certificate config file
+            or the certificate file cannot be found after retries.
+    """
+    import json
+
+    cert_config_path = os.environ.get(environment_vars.GOOGLE_API_CERTIFICATE_CONFIG)
+    if not cert_config_path:
+        return None
+
+    has_logged_warning = False
+
+    for interval in _POLLING_INTERVALS:
+        try:
+            with open(cert_config_path, "r") as f:
+                cert_config = json.load(f)
+                cert_path = (
+                    cert_config.get("cert_configs", {})
+                    .get("workload", {})
+                    .get("cert_path")
+                )
+                if _is_certificate_file_ready(cert_path):
+                    return cert_path
+        except (IOError, ValueError, KeyError):
+            if not has_logged_warning:
+                _LOGGER.warning(
+                    "Certificate config file not found at %s (from %s environment "
+                    "variable). Retrying for up to %s seconds.",
+                    cert_config_path,
+                    environment_vars.GOOGLE_API_CERTIFICATE_CONFIG,
+                    _TOTAL_TIMEOUT,
+                )
+                has_logged_warning = True
+            pass
+
+        # As a fallback, check the well-known certificate path.
+        if _is_certificate_file_ready(_WELL_KNOWN_CERT_PATH):
+            return _WELL_KNOWN_CERT_PATH
+
+        # A sleep is required in two cases:
+        # 1. The config file is not found (the except block).
+        # 2. The config file is found, but the certificate is not yet available.
+        # In both cases, we need to poll, so we sleep on every iteration
+        # that doesn't return a certificate.
+        time.sleep(interval)
+
+    raise exceptions.RefreshError(
+        "Certificate config or certificate file not found after multiple retries. "
+        f"Token binding protection is failing. You can turn off this protection by setting "
+        f"{environment_vars.GOOGLE_API_PREVENT_AGENT_TOKEN_SHARING_FOR_GCP_SERVICES} to false "
+        "to fall back to unbound tokens."
+    )
+
+
+def get_and_parse_agent_identity_certificate():
+    """Gets and parses the agent identity certificate if not opted out.
+
+    Checks if the user has opted out of certificate-bound tokens. If not,
+    it gets the certificate path, reads the file, and parses it.
+
+    Returns:
+        The parsed certificate object if found and not opted out, otherwise None.
+    """
+    # If the user has opted out of cert bound tokens, there is no need to
+    # look up the certificate.
+    is_opted_out = (
+        os.environ.get(
+            environment_vars.GOOGLE_API_PREVENT_AGENT_TOKEN_SHARING_FOR_GCP_SERVICES,
+            "true",
+        ).lower()
+        == "false"
+    )
+    if is_opted_out:
+        return None
+
+    cert_path = get_agent_identity_certificate_path()
+    if not cert_path:
+        return None
+
+    with open(cert_path, "rb") as cert_file:
+        cert_bytes = cert_file.read()
+
+    return parse_certificate(cert_bytes)
+
+
+def parse_certificate(cert_bytes):
+    """Parses a PEM-encoded certificate.
+
+    Args:
+        cert_bytes (bytes): The PEM-encoded certificate bytes.
+
+    Returns:
+        cryptography.x509.Certificate: The parsed certificate object.
+    """
+    try:
+        from cryptography import x509
+
+        return x509.load_pem_x509_certificate(cert_bytes)
+    except ImportError as e:
+        raise ImportError(CRYPTOGRAPHY_NOT_FOUND_ERROR) from e
+
+
+def _is_agent_identity_certificate(cert):
+    """Checks if a certificate is an Agent Identity certificate.
+
+    This is determined by checking the Subject Alternative Name (SAN) for a
+    SPIFFE ID with a trust domain matching Agent Identity patterns.
+
+    Args:
+        cert (cryptography.x509.Certificate): The parsed certificate object.
+
+    Returns:
+        bool: True if the certificate is an Agent Identity certificate,
+            False otherwise.
+    """
+    try:
+        from cryptography import x509
+        from cryptography.x509.oid import ExtensionOID
+
+        try:
+            ext = cert.extensions.get_extension_for_oid(
+                ExtensionOID.SUBJECT_ALTERNATIVE_NAME
+            )
+        except x509.ExtensionNotFound:
+            return False
+        uris = ext.value.get_values_for_type(x509.UniformResourceIdentifier)
+
+        for uri in uris:
+            parsed_uri = urlparse(uri)
+            if parsed_uri.scheme == "spiffe":
+                trust_domain = parsed_uri.netloc
+                for pattern in _AGENT_IDENTITY_SPIFFE_TRUST_DOMAIN_PATTERNS:
+                    if re.match(pattern, trust_domain):
+                        return True
+        return False
+    except ImportError as e:
+        raise ImportError(CRYPTOGRAPHY_NOT_FOUND_ERROR) from e
+
+
+def calculate_certificate_fingerprint(cert):
+    """Calculates the URL-encoded, unpadded, base64-encoded SHA256 hash of a
+    DER-encoded certificate.
+
+    Args:
+        cert (cryptography.x509.Certificate): The parsed certificate object.
+
+    Returns:
+        str: The URL-encoded, unpadded, base64-encoded SHA256 fingerprint.
+    """
+    try:
+        from cryptography.hazmat.primitives import serialization
+
+        der_cert = cert.public_bytes(serialization.Encoding.DER)
+        fingerprint = hashlib.sha256(der_cert).digest()
+        # The certificate fingerprint is generated in two steps to align with GFE's
+        # expectations and ensure proper URL transmission:
+        # 1. Standard base64 encoding is applied, and padding ('=') is removed.
+        # 2. The resulting string is then URL-encoded to handle special characters
+        #    ('+', '/') that would otherwise be misinterpreted in URL parameters.
+        base64_fingerprint = base64.b64encode(fingerprint).decode("utf-8")
+        unpadded_base64_fingerprint = base64_fingerprint.rstrip("=")
+        return quote(unpadded_base64_fingerprint)
+    except ImportError as e:
+        raise ImportError(CRYPTOGRAPHY_NOT_FOUND_ERROR) from e
+
+
+def should_request_bound_token(cert):
+    """Determines if a bound token should be requested.
+
+    This is based on the GOOGLE_API_PREVENT_AGENT_TOKEN_SHARING_FOR_GCP_SERVICES
+    environment variable and whether the certificate is an agent identity cert.
+
+    Args:
+        cert (cryptography.x509.Certificate): The parsed certificate object.
+
+    Returns:
+        bool: True if a bound token should be requested, False otherwise.
+    """
+    is_agent_cert = _is_agent_identity_certificate(cert)
+    is_opted_in = (
+        os.environ.get(
+            environment_vars.GOOGLE_API_PREVENT_AGENT_TOKEN_SHARING_FOR_GCP_SERVICES,
+            "true",
+        ).lower()
+        == "true"
+    )
+    return is_agent_cert and is_opted_in
+
+
+def call_client_cert_callback():
+    """Calls the client cert callback and returns the certificate and key."""
+    _, cert_bytes, key_bytes, passphrase = _mtls_helper.get_client_ssl_credentials(
+        generate_encrypted_key=True
+    )
+    return cert_bytes, key_bytes
+
+
+def get_cached_cert_fingerprint(cached_cert):
+    """Returns the fingerprint of the cached certificate."""
+    if cached_cert:
+        cert_obj = parse_certificate(cached_cert)
+        cached_cert_fingerprint = calculate_certificate_fingerprint(cert_obj)
+    else:
+        raise ValueError("mTLS connection is not configured.")
+    return cached_cert_fingerprint

backend_service/venv/lib/python3.13/site-packages/google/auth/_cache.py

@@ -0,0 +1,64 @@
+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from collections import OrderedDict
+
+
+class LRUCache(dict):
+    def __init__(self, maxsize):
+        super().__init__()
+        self._order = OrderedDict()
+        self.maxsize = maxsize
+
+    def clear(self):
+        super().clear()
+        self._order.clear()
+
+    def get(self, key, default=None):
+        try:
+            value = super().__getitem__(key)
+            self._update(key)
+            return value
+        except KeyError:
+            return default
+
+    def __getitem__(self, key):
+        value = super().__getitem__(key)
+        self._update(key)
+        return value
+
+    def __setitem__(self, key, value):
+        maxsize = self.maxsize
+        if maxsize <= 0:
+            return
+        if key not in self:
+            while len(self) >= maxsize:
+                self.popitem()
+        super().__setitem__(key, value)
+        self._update(key)
+
+    def __delitem__(self, key):
+        super().__delitem__(key)
+        del self._order[key]
+
+    def popitem(self):
+        """Remove and return the least recently used key-value pair."""
+        key, _ = self._order.popitem(last=False)
+        return key, super().pop(key)
+
+    def _update(self, key):
+        try:
+            self._order.move_to_end(key)
+        except KeyError:
+            self._order[key] = None

backend_service/venv/lib/python3.13/site-packages/google/auth/compute_engine/_mtls.py

@@ -0,0 +1,164 @@
+# -*- coding: utf-8 -*-
+#
+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+"""Mutual TLS for Google Compute Engine metadata server."""
+
+from dataclasses import dataclass, field
+import enum
+import logging
+import os
+from pathlib import Path
+import ssl
+from urllib.parse import urlparse, urlunparse
+
+import requests
+from requests.adapters import HTTPAdapter
+
+from google.auth import environment_vars, exceptions
+
+
+_LOGGER = logging.getLogger(__name__)
+
+_WINDOWS_OS_NAME = "nt"
+
+# MDS mTLS certificate paths based on OS.
+# Documentation to well known locations can be found at:
+# https://cloud.google.com/compute/docs/metadata/overview#https-mds-certificates
+_WINDOWS_MTLS_COMPONENTS_BASE_PATH = Path("C:/ProgramData/Google/ComputeEngine")
+_MTLS_COMPONENTS_BASE_PATH = Path("/run/google-mds-mtls")
+
+
+def _get_mds_root_crt_path():
+    if os.name == _WINDOWS_OS_NAME:
+        return _WINDOWS_MTLS_COMPONENTS_BASE_PATH / "mds-mtls-root.crt"
+    else:
+        return _MTLS_COMPONENTS_BASE_PATH / "root.crt"
+
+
+def _get_mds_client_combined_cert_path():
+    if os.name == _WINDOWS_OS_NAME:
+        return _WINDOWS_MTLS_COMPONENTS_BASE_PATH / "mds-mtls-client.key"
+    else:
+        return _MTLS_COMPONENTS_BASE_PATH / "client.key"
+
+
+@dataclass
+class MdsMtlsConfig:
+    ca_cert_path: Path = field(
+        default_factory=_get_mds_root_crt_path
+    )  # path to CA certificate
+    client_combined_cert_path: Path = field(
+        default_factory=_get_mds_client_combined_cert_path
+    )  # path to file containing client certificate and key
+
+
+def _certs_exist(mds_mtls_config: MdsMtlsConfig):
+    """Checks if the mTLS certificates exist."""
+    return os.path.exists(mds_mtls_config.ca_cert_path) and os.path.exists(
+        mds_mtls_config.client_combined_cert_path
+    )
+
+
+class MdsMtlsMode(enum.Enum):
+    """MDS mTLS mode. Used to configure connection behavior when connecting to MDS.
+
+    STRICT: Always use HTTPS/mTLS.  If certificates are not found locally, an error will be returned.
+    NONE: Never use mTLS. Requests will use regular HTTP.
+    DEFAULT: Use mTLS if certificates are found locally, otherwise use regular HTTP.
+    """
+
+    STRICT = "strict"
+    NONE = "none"
+    DEFAULT = "default"
+
+
+def _parse_mds_mode():
+    """Parses the GCE_METADATA_MTLS_MODE environment variable."""
+    mode_str = os.environ.get(
+        environment_vars.GCE_METADATA_MTLS_MODE, "default"
+    ).lower()
+    try:
+        return MdsMtlsMode(mode_str)
+    except ValueError:
+        raise ValueError(
+            "Invalid value for GCE_METADATA_MTLS_MODE. Must be one of 'strict', 'none', or 'default'."
+        )
+
+
+def should_use_mds_mtls(mds_mtls_config: MdsMtlsConfig = MdsMtlsConfig()):
+    """Determines if mTLS should be used for the metadata server."""
+    mode = _parse_mds_mode()
+    if mode == MdsMtlsMode.STRICT:
+        if not _certs_exist(mds_mtls_config):
+            raise exceptions.MutualTLSChannelError(
+                "mTLS certificates not found in strict mode."
+            )
+        return True
+    elif mode == MdsMtlsMode.NONE:
+        return False
+    else:  # Default mode
+        return _certs_exist(mds_mtls_config)
+
+
+class MdsMtlsAdapter(HTTPAdapter):
+    """An HTTP adapter that uses mTLS for the metadata server."""
+
+    def __init__(
+        self, mds_mtls_config: MdsMtlsConfig = MdsMtlsConfig(), *args, **kwargs
+    ):
+        self.ssl_context = ssl.create_default_context()
+        self.ssl_context.load_verify_locations(cafile=mds_mtls_config.ca_cert_path)
+        self.ssl_context.load_cert_chain(
+            certfile=mds_mtls_config.client_combined_cert_path
+        )
+        super(MdsMtlsAdapter, self).__init__(*args, **kwargs)
+
+    def init_poolmanager(self, *args, **kwargs):
+        kwargs["ssl_context"] = self.ssl_context
+        return super(MdsMtlsAdapter, self).init_poolmanager(*args, **kwargs)
+
+    def proxy_manager_for(self, *args, **kwargs):
+        kwargs["ssl_context"] = self.ssl_context
+        return super(MdsMtlsAdapter, self).proxy_manager_for(*args, **kwargs)
+
+    def send(self, request, **kwargs):
+        # If we are in strict mode, always use mTLS (no HTTP fallback)
+        if _parse_mds_mode() == MdsMtlsMode.STRICT:
+            return super(MdsMtlsAdapter, self).send(request, **kwargs)
+
+        # In default mode, attempt mTLS first, then fallback to HTTP on failure
+        try:
+            response = super(MdsMtlsAdapter, self).send(request, **kwargs)
+            response.raise_for_status()
+            return response
+        except (
+            ssl.SSLError,
+            requests.exceptions.SSLError,
+            requests.exceptions.HTTPError,
+        ) as e:
+            _LOGGER.warning(
+                "mTLS connection to Compute Engine Metadata server failed. "
+                "Falling back to standard HTTP. Reason: %s",
+                e,
+            )
+            # Fallback to standard HTTP
+            parsed_original_url = urlparse(request.url)
+            http_fallback_url = urlunparse(parsed_original_url._replace(scheme="http"))
+            request.url = http_fallback_url
+
+            # Use a standard HTTPAdapter for the fallback
+            http_adapter = HTTPAdapter()
+            return http_adapter.send(request, **kwargs)

backend_service/venv/lib/python3.13/site-packages/google/auth/crypt/es.py

@@ -0,0 +1,221 @@
+# Copyright 2017 Google Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""ECDSA verifier and signer that use the ``cryptography`` library.
+"""
+
+from dataclasses import dataclass
+from typing import Any, Dict, Optional, Union
+
+import cryptography.exceptions
+from cryptography.hazmat import backends
+from cryptography.hazmat.primitives import hashes
+from cryptography.hazmat.primitives import serialization
+from cryptography.hazmat.primitives.asymmetric import ec
+from cryptography.hazmat.primitives.asymmetric import padding
+from cryptography.hazmat.primitives.asymmetric.utils import decode_dss_signature
+from cryptography.hazmat.primitives.asymmetric.utils import encode_dss_signature
+import cryptography.x509
+
+from google.auth import _helpers
+from google.auth.crypt import base
+
+
+_CERTIFICATE_MARKER = b"-----BEGIN CERTIFICATE-----"
+_BACKEND = backends.default_backend()
+_PADDING = padding.PKCS1v15()
+
+
+@dataclass
+class _ESAttributes:
+    """A class that models ECDSA attributes.
+
+    Attributes:
+        rs_size (int): Size for ASN.1 r and s size.
+        sha_algo (hashes.HashAlgorithm): Hash algorithm.
+        algorithm (str): Algorithm name.
+    """
+
+    rs_size: int
+    sha_algo: hashes.HashAlgorithm
+    algorithm: str
+
+    @classmethod
+    def from_key(
+        cls, key: Union[ec.EllipticCurvePublicKey, ec.EllipticCurvePrivateKey]
+    ):
+        return cls.from_curve(key.curve)
+
+    @classmethod
+    def from_curve(cls, curve: ec.EllipticCurve):
+        # ECDSA raw signature has (r||s) format where r,s are two
+        # integers of size 32 bytes for P-256 curve and 48 bytes
+        # for P-384 curve. For P-256 curve, we use SHA256 hash algo,
+        # and for P-384 curve we use SHA384 algo.
+        if isinstance(curve, ec.SECP384R1):
+            return cls(48, hashes.SHA384(), "ES384")
+        else:
+            # default to ES256
+            return cls(32, hashes.SHA256(), "ES256")
+
+
+class EsVerifier(base.Verifier):
+    """Verifies ECDSA cryptographic signatures using public keys.
+
+    Args:
+        public_key (
+                cryptography.hazmat.primitives.asymmetric.ec.EllipticCurvePublicKey):
+            The public key used to verify signatures.
+    """
+
+    def __init__(self, public_key: ec.EllipticCurvePublicKey) -> None:
+        self._pubkey = public_key
+        self._attributes = _ESAttributes.from_key(public_key)
+
+    @_helpers.copy_docstring(base.Verifier)
+    def verify(self, message: bytes, signature: bytes) -> bool:
+        # First convert (r||s) raw signature to ASN1 encoded signature.
+        sig_bytes = _helpers.to_bytes(signature)
+        if len(sig_bytes) != self._attributes.rs_size * 2:
+            return False
+        r = int.from_bytes(sig_bytes[: self._attributes.rs_size], byteorder="big")
+        s = int.from_bytes(sig_bytes[self._attributes.rs_size :], byteorder="big")
+        asn1_sig = encode_dss_signature(r, s)
+
+        message = _helpers.to_bytes(message)
+        try:
+            self._pubkey.verify(asn1_sig, message, ec.ECDSA(self._attributes.sha_algo))
+            return True
+        except (ValueError, cryptography.exceptions.InvalidSignature):
+            return False
+
+    @classmethod
+    def from_string(cls, public_key: Union[str, bytes]) -> "EsVerifier":
+        """Construct an Verifier instance from a public key or public
+        certificate string.
+
+        Args:
+            public_key (Union[str, bytes]): The public key in PEM format or the
+                x509 public key certificate.
+
+        Returns:
+            Verifier: The constructed verifier.
+
+        Raises:
+            ValueError: If the public key can't be parsed.
+        """
+        public_key_data = _helpers.to_bytes(public_key)
+
+        if _CERTIFICATE_MARKER in public_key_data:
+            cert = cryptography.x509.load_pem_x509_certificate(
+                public_key_data, _BACKEND
+            )
+            pubkey = cert.public_key()  # type: Any
+
+        else:
+            pubkey = serialization.load_pem_public_key(public_key_data, _BACKEND)
+
+        if not isinstance(pubkey, ec.EllipticCurvePublicKey):
+            raise TypeError("Expected public key of type EllipticCurvePublicKey")
+
+        return cls(pubkey)
+
+
+class EsSigner(base.Signer, base.FromServiceAccountMixin):
+    """Signs messages with an ECDSA private key.
+
+    Args:
+        private_key (
+                cryptography.hazmat.primitives.asymmetric.ec.EllipticCurvePrivateKey):
+            The private key to sign with.
+        key_id (str): Optional key ID used to identify this private key. This
+            can be useful to associate the private key with its associated
+            public key or certificate.
+    """
+
+    def __init__(
+        self, private_key: ec.EllipticCurvePrivateKey, key_id: Optional[str] = None
+    ) -> None:
+        self._key = private_key
+        self._key_id = key_id
+        self._attributes = _ESAttributes.from_key(private_key)
+
+    @property
+    def algorithm(self) -> str:
+        """Name of the algorithm used to sign messages.
+        Returns:
+            str: The algorithm name.
+        """
+        return self._attributes.algorithm
+
+    @property  # type: ignore
+    @_helpers.copy_docstring(base.Signer)
+    def key_id(self) -> Optional[str]:
+        return self._key_id
+
+    @_helpers.copy_docstring(base.Signer)
+    def sign(self, message: bytes) -> bytes:
+        message = _helpers.to_bytes(message)
+        asn1_signature = self._key.sign(message, ec.ECDSA(self._attributes.sha_algo))
+
+        # Convert ASN1 encoded signature to (r||s) raw signature.
+        (r, s) = decode_dss_signature(asn1_signature)
+        return r.to_bytes(self._attributes.rs_size, byteorder="big") + s.to_bytes(
+            self._attributes.rs_size, byteorder="big"
+        )
+
+    @classmethod
+    def from_string(
+        cls, key: Union[bytes, str], key_id: Optional[str] = None
+    ) -> "EsSigner":
+        """Construct a RSASigner from a private key in PEM format.
+
+        Args:
+            key (Union[bytes, str]): Private key in PEM format.
+            key_id (str): An optional key id used to identify the private key.
+
+        Returns:
+            google.auth.crypt._cryptography_rsa.RSASigner: The
+            constructed signer.
+
+        Raises:
+            ValueError: If ``key`` is not ``bytes`` or ``str`` (unicode).
+            UnicodeDecodeError: If ``key`` is ``bytes`` but cannot be decoded
+                into a UTF-8 ``str``.
+            ValueError: If ``cryptography`` "Could not deserialize key data."
+        """
+        key_bytes = _helpers.to_bytes(key)
+        private_key = serialization.load_pem_private_key(
+            key_bytes, password=None, backend=_BACKEND
+        )
+
+        if not isinstance(private_key, ec.EllipticCurvePrivateKey):
+            raise TypeError("Expected private key of type EllipticCurvePrivateKey")
+
+        return cls(private_key, key_id=key_id)
+
+    def __getstate__(self) -> Dict[str, Any]:
+        """Pickle helper that serializes the _key attribute."""
+        state = self.__dict__.copy()
+        state["_key"] = self._key.private_bytes(
+            encoding=serialization.Encoding.PEM,
+            format=serialization.PrivateFormat.PKCS8,
+            encryption_algorithm=serialization.NoEncryption(),
+        )
+        return state
+
+    def __setstate__(self, state: Dict[str, Any]) -> None:
+        """Pickle helper that deserializes the _key attribute."""
+        state["_key"] = serialization.load_pem_private_key(state["_key"], None)
+        self.__dict__.update(state)