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leocrm/app/core/delegation_token.py
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Phase 5: AI/MCP Bearer-Auth + Delegationstoken + Audit
5.1 Delegationstoken (app/core/delegation_token.py):
- HMAC-SHA256 signiert mit SECRET_KEY, max 60s Lifetime
- Payload: user_id, tenant_id, agent_id, audience, expires_at, token_id
- Statelose Verifikation, Audience-Check, Expiry-Check

5.2 MCP Bearer-Auth:
- app/core/api_token.py: Token Service (create, verify, revoke, list)
- app/deps.py: get_current_user_bearer + get_current_user_or_bearer
- app/routes/api_tokens.py: Token CRUD Routes (create, list, revoke)
- MCP Server Routes: get_current_user_or_bearer akzeptiert Session + Bearer

5.3 Methodenrechte:
- MCP nutzt bereits mcp:read/mcp:write basierend auf tool_def.required_permission

5.5 Audit:
- MCP Tool-Ausfuehrung wird protokolliert (log_audit mit correlation_id)

Tests: 13/13 bestanden (7 API Token + 6 Delegation Token)
2026-08-03 14:06:55 +02:00

94 lines
3.0 KiB
Python

"""Delegation Token Service — HMAC-signed short-lived tokens for internal AI calls.
Tokens are signed with the app SECRET_KEY using HMAC-SHA256.
Max lifetime: 60 seconds. No persistent storage — stateless verification.
Token format: base64(payload).base64(signature)
"""
from __future__ import annotations
import base64
import hashlib
import hmac
import json
import uuid
from datetime import UTC, datetime, timedelta
from typing import Any
from app.config import get_settings
DELEGATION_AUDIENCE = "internal-ai-delegation"
MAX_TOKEN_LIFETIME = 60 # seconds
def _get_secret() -> bytes:
"""Get the signing secret from app settings."""
return get_settings().secret_key.encode()
def _sign(payload: dict) -> str:
"""Sign payload with HMAC-SHA256 and return base64(payload).base64(sig)."""
payload_bytes = json.dumps(payload, sort_keys=True, separators=(",", ":")).encode()
sig = hmac.new(_get_secret(), payload_bytes, hashlib.sha256).digest()
return f"{base64.b64encode(payload_bytes).decode()}.{base64.b64encode(sig).decode()}"
def _verify(token: str) -> dict | None:
"""Verify a delegation token. Returns payload dict or None."""
try:
payload_b64, sig_b64 = token.rsplit(".", 1)
payload_bytes = base64.b64decode(payload_b64)
expected_sig = hmac.new(_get_secret(), payload_bytes, hashlib.sha256).digest()
actual_sig = base64.b64decode(sig_b64)
if not hmac.compare_digest(expected_sig, actual_sig):
return None
payload = json.loads(payload_bytes)
# Check expiry
now = datetime.now(UTC)
expires_at = datetime.fromisoformat(payload["expires_at"])
if expires_at.tzinfo is None:
expires_at = expires_at.replace(tzinfo=UTC)
if now > expires_at:
return None
# Check audience
if payload.get("audience") != DELEGATION_AUDIENCE:
return None
return payload
except Exception:
return None
def create_delegation_token(
user_id: str,
tenant_id: str,
agent_id: str = "ai-copilot",
lifetime_seconds: int = MAX_TOKEN_LIFETIME,
) -> str:
"""Create a short-lived delegation token for an internal AI call.
The token contains:
- user_id, tenant_id: who the AI acts on behalf of
- agent_id: which agent/service is calling
- audience: fixed to internal-ai-delegation
- expires_at: max 60 seconds from now
- token_id: unique ID for audit tracing
"""
now = datetime.now(UTC)
expires_at = now + timedelta(seconds=min(lifetime_seconds, MAX_TOKEN_LIFETIME))
payload = {
"user_id": user_id,
"tenant_id": tenant_id,
"agent_id": agent_id,
"audience": DELEGATION_AUDIENCE,
"expires_at": expires_at.isoformat(),
"token_id": str(uuid.uuid4()),
}
return _sign(payload)
def verify_delegation_token(token: str) -> dict[str, Any] | None:
"""Verify a delegation token. Returns payload or None if invalid/expired."""
return _verify(token)