92 lines
3.5 KiB
Python
92 lines
3.5 KiB
Python
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# Part of Odoo. See LICENSE file for full copyright and licensing details.
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import base64
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import hashlib
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import json
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import binascii
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import time
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import enum
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import hmac
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from cryptography.hazmat.backends import default_backend
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from cryptography.hazmat.primitives import hashes, serialization
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from cryptography.hazmat.primitives.asymmetric import ec, utils
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class Algorithm(enum.Enum):
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ES256 = "ES256" # ECDSA SHA-256
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HS256 = "HS256" # HMAC SHA-256
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def _generate_keys(key_encoding, key_format) -> (bytes, bytes):
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private_object = ec.generate_private_key(ec.SECP256R1(), default_backend())
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private_int = private_object.private_numbers().private_value
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private_bytes = private_int.to_bytes(32, "big")
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public_object = private_object.public_key()
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public_bytes = public_object.public_bytes(
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encoding=key_encoding,
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format=key_format,
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)
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return private_bytes, public_bytes
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def generate_vapid_keys() -> (str, str):
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"""
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Generate the VAPID (Voluntary Application Server Identification) used for the Web Push
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This function generates a signing key pair usable with the Elliptic Curve Digital
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Signature Algorithm (ECDSA) over the P-256 curve.
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https://www.rfc-editor.org/rfc/rfc8292
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:return: tuple (private_key, public_key)
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"""
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private, public = _generate_keys(serialization.Encoding.X962, serialization.PublicFormat.UncompressedPoint)
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private_string = base64.urlsafe_b64encode(private).decode("ascii").strip("=")
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public_string = base64.urlsafe_b64encode(public).decode("ascii").strip("=")
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return private_string, public_string
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def base64_decode_with_padding(value: str) -> bytes:
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return base64.urlsafe_b64decode(value + "==")
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def _generate_jwt(claims: dict, key: str, algorithm: Algorithm) -> str:
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JOSE_header = base64.urlsafe_b64encode(json.dumps({"typ": "JWT", "alg": algorithm.value}).encode())
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payload = base64.urlsafe_b64encode(json.dumps(claims).encode())
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unsigned_token = "{}.{}".format(JOSE_header.decode().strip("="), payload.decode().strip("="))
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key_decoded = base64_decode_with_padding(key)
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match algorithm:
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case Algorithm.HS256:
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signature = hmac.new(key_decoded, unsigned_token.encode(), hashlib.sha256).digest()
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sig = base64.urlsafe_b64encode(signature)
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case Algorithm.ES256:
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# Retrieve the private key using a P256 elliptic curve
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private_key = ec.derive_private_key(
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int(binascii.hexlify(key_decoded), 16), ec.SECP256R1(), default_backend()
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)
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signature = private_key.sign(unsigned_token.encode(), ec.ECDSA(hashes.SHA256()))
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(r, s) = utils.decode_dss_signature(signature)
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sig = base64.urlsafe_b64encode(r.to_bytes(32, "big") + s.to_bytes(32, "big"))
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case _:
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raise ValueError(f"Unsupported algorithm: {algorithm}")
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return "{}.{}".format(unsigned_token, sig.decode().strip("="))
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def sign(claims: dict, key: str, ttl: int, algorithm: Algorithm) -> str:
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"""
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A JSON Web Token is a signed pair of JSON objects, turned into base64 strings.
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RFC: https://www.rfc-editor.org/rfc/rfc7519
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:param claims: the payload of the jwt: https://www.rfc-editor.org/rfc/rfc7519#section-4.1
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:param key: base64 string
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:param ttl: the time to live of the token in seconds ('exp' claim)
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:param algorithm: to use to sign the token
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:return: JSON Web Token
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"""
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non_padded_key = key.strip("=")
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assert ttl
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claims["exp"] = int(time.time()) + ttl
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return _generate_jwt(claims, non_padded_key, algorithm=algorithm)
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