hdp-crewai

HDP (Human Delegation Provenance) middleware for CrewAI — attach a cryptographic audit trail to any multi-agent crew with zero changes to your existing code.

Every task a CrewAI crew executes on behalf of a human is recorded in a tamper-evident chain of Ed25519 signatures, verifiable offline with a single public key.

pip install hdp-crewai

Quick start

from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PrivateKey
from crewai import Agent, Crew, Task
from hdp_crewai import HdpMiddleware, HdpPrincipal, ScopePolicy, verify_chain

# 1. Your signing key (store in a secrets manager, never in code)
private_key = Ed25519PrivateKey.generate()

# 2. Define what the human is authorising
scope = ScopePolicy(
    intent="Analyse Q1 sales data and produce a summary",
    authorized_tools=["FileReadTool", "CSVAnalysisTool"],
    max_hops=5,
)

# 3. Create the middleware
middleware = HdpMiddleware(
    signing_key=private_key.private_bytes_raw(),
    session_id="q1-review-2026",
    principal=HdpPrincipal(id="analyst@company.com", id_type="email"),
    scope=scope,
)

# 4. Build your crew as normal
crew = Crew(agents=[...], tasks=[...])

# 5. Attach HDP — one line, zero crew changes
middleware.configure(crew)
crew.kickoff()

# 6. Verify the delegation chain offline
result = verify_chain(middleware.export_token(), private_key.public_key())
print(result.valid, result.hop_count, result.violations)

Five design considerations

API reference

HdpMiddleware

HdpMiddleware(
    signing_key: bytes,          # Ed25519 private key (raw 32 bytes)
    session_id: str,             # unique ID for this crew run
    principal: HdpPrincipal,     # the human delegating authority
    scope: ScopePolicy,          # what is authorised
    key_id: str = "default",     # label stored in the token header
    expires_in_ms: int = 86400000,
    strict: bool = False,        # True → raise on scope violations
    persist_token: bool = True,  # False → skip storage write
)

verify_chain(token, public_key)

result = verify_chain(token_dict, public_key)  # Ed25519PublicKey or raw bytes
result.valid        # bool
result.hop_count    # int
result.violations   # list[str]
result.hop_results  # list[HopVerification]

ScopePolicy

ScopePolicy(
    intent: str,
    data_classification: str = "internal",   # "public" | "internal" | "confidential" | "restricted"
    network_egress: bool = True,
    persistence: bool = False,
    authorized_tools: list[str] | None = None,
    authorized_resources: list[str] | None = None,
    max_hops: int | None = None,
)

Spec

Human Delegation Provenance (HDP) is an IETF draft: draft-helixar-hdp-agentic-delegation

License

Apache License 2.0 — Helixar Limited