giles
1a74d811f7
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Merges full history from art-dag/mono.git into the monorepo under the artdag/ directory. Contains: core (DAG engine), l1 (Celery rendering server), l2 (ActivityPub registry), common (shared templates/middleware), client (CLI), test (e2e). Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com> git-subtree-dir: artdag git-subtree-mainline:1a179de547git-subtree-split:4c2e716558
85 lines
2.5 KiB
Python
85 lines
2.5 KiB
Python
"""HTTP Signature verification for incoming AP-style inbox requests.
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Implements the same RSA-SHA256 / PKCS1v15 scheme used by the coop's
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shared/utils/http_signatures.py, but only the verification side.
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"""
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from __future__ import annotations
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import base64
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import re
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from cryptography.hazmat.primitives import hashes, serialization
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from cryptography.hazmat.primitives.asymmetric import padding
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def verify_request_signature(
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public_key_pem: str,
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signature_header: str,
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method: str,
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path: str,
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headers: dict[str, str],
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) -> bool:
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"""Verify an incoming HTTP Signature.
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Args:
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public_key_pem: PEM-encoded public key of the sender.
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signature_header: Value of the ``Signature`` header.
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method: HTTP method (GET, POST, etc.).
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path: Request path (e.g. ``/inbox``).
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headers: All request headers (case-insensitive keys).
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Returns:
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True if the signature is valid.
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"""
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parts = _parse_signature_header(signature_header)
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signed_headers = parts.get("headers", "date").split()
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signature_b64 = parts.get("signature", "")
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# Reconstruct the signed string
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lc_headers = {k.lower(): v for k, v in headers.items()}
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lines: list[str] = []
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for h in signed_headers:
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if h == "(request-target)":
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lines.append(f"(request-target): {method.lower()} {path}")
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else:
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lines.append(f"{h}: {lc_headers.get(h, '')}")
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signed_string = "\n".join(lines)
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public_key = serialization.load_pem_public_key(public_key_pem.encode())
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try:
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public_key.verify(
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base64.b64decode(signature_b64),
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signed_string.encode(),
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padding.PKCS1v15(),
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hashes.SHA256(),
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)
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return True
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except Exception:
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return False
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def parse_key_id(signature_header: str) -> str:
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"""Extract the keyId from a Signature header.
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keyId is typically ``https://domain/users/username#main-key``.
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Returns the actor URL (strips ``#main-key``).
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"""
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parts = _parse_signature_header(signature_header)
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key_id = parts.get("keyId", "")
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return re.sub(r"#.*$", "", key_id)
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def _parse_signature_header(header: str) -> dict[str, str]:
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"""Parse a Signature header into its component parts."""
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parts: dict[str, str] = {}
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for part in header.split(","):
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part = part.strip()
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eq = part.find("=")
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if eq < 0:
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continue
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key = part[:eq]
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val = part[eq + 1:].strip('"')
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parts[key] = val
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return parts
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