120 lines
4.6 KiB
Python
120 lines
4.6 KiB
Python
"""Mutual Feasibility Receipt v2 (MFR-v2)
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Compact, byte-stable receipt suitable for DTN-era custody handoffs. This
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implementation focuses on a small JSON representation with deterministic
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serialization and an HMAC-based signature for tests/POC. Fields are chosen to
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keep serialized size <= 512 bytes in typical use.
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Fields (compact):
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- receipt_id: short random id
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- proposal_hash: short hex digest of proposal
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- invariant_id_set: list[int] (small ints)
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- decision: "ok"/"partial"/"deny"
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- uncertainty_pct: coarse uncertainty percent (0..100)
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- pass_ticket_hash: optional hex pointer to pre-signed ticket
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- execution_hash_skim: optional short hex prefix (e.g., blake2b prefix)
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- round_nonce, ts, signer, sig
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"""
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from dataclasses import dataclass
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from typing import List, Optional
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import time
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import uuid
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import json
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import hmac
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import hashlib
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@dataclass
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class MutualFeasibilityReceiptV2:
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receipt_id: str
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proposal_hash: str
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invariant_id_set: List[int]
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decision: str
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uncertainty_pct: int
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round_nonce: int
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ts: float
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pass_ticket_hash: str = ""
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execution_hash_skim: str = ""
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signer: str = ""
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sig: str = ""
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@classmethod
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def create(cls, proposal_hash: str, invariant_id_set: List[int], decision: str,
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uncertainty_pct: int = 0, round_nonce: int = 0,
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pass_ticket_hash: Optional[str] = None,
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execution_hash_skim: Optional[str] = None,
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signer: str = "", key: Optional[bytes] = None) -> "MutualFeasibilityReceiptV2":
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rid = uuid.uuid4().hex[:12]
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ts = time.time()
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r = cls(receipt_id=rid, proposal_hash=proposal_hash,
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invariant_id_set=list(invariant_id_set), decision=decision,
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uncertainty_pct=int(uncertainty_pct), round_nonce=int(round_nonce), ts=ts,
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pass_ticket_hash=pass_ticket_hash or "",
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execution_hash_skim=execution_hash_skim or "",
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signer=signer, sig="")
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if key:
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r.sig = r._sign(key)
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return r
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def _canonical_payload(self) -> str:
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# deterministic and compact JSON over authoritative fields (exclude sig)
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payload = {
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"receipt_id": self.receipt_id,
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"proposal_hash": self.proposal_hash,
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"invariant_id_set": self.invariant_id_set,
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"decision": self.decision,
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"uncertainty_pct": int(self.uncertainty_pct),
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"round_nonce": int(self.round_nonce),
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"ts": int(self.ts),
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"pass_ticket_hash": self.pass_ticket_hash,
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"execution_hash_skim": self.execution_hash_skim,
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"signer": self.signer,
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}
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return json.dumps(payload, sort_keys=True, separators=(",", ":"))
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def _sign(self, key: bytes) -> str:
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h = hmac.new(key, self._canonical_payload().encode("utf-8"), hashlib.blake2b)
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# use hex digest truncated to 64 chars to keep sizes small
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return h.hexdigest()[:64]
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def verify(self, key: bytes) -> bool:
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if not self.sig:
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return False
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expected = self._sign(key)
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return hmac.compare_digest(expected, self.sig)
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def serialize(self) -> bytes:
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obj = {
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"receipt_id": self.receipt_id,
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"proposal_hash": self.proposal_hash,
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"invariant_id_set": self.invariant_id_set,
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"decision": self.decision,
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"uncertainty_pct": self.uncertainty_pct,
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"round_nonce": self.round_nonce,
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"ts": self.ts,
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"pass_ticket_hash": self.pass_ticket_hash,
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"execution_hash_skim": self.execution_hash_skim,
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"signer": self.signer,
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"sig": self.sig,
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}
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return json.dumps(obj, sort_keys=True, separators=(",", ":")).encode("utf-8")
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@classmethod
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def deserialize(cls, b: bytes) -> "MutualFeasibilityReceiptV2":
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obj = json.loads(b.decode("utf-8"))
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return cls(receipt_id=obj.get("receipt_id", ""),
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proposal_hash=obj.get("proposal_hash", ""),
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invariant_id_set=[int(x) for x in obj.get("invariant_id_set", [])],
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decision=obj.get("decision", "deny"),
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uncertainty_pct=int(obj.get("uncertainty_pct", 0)),
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round_nonce=int(obj.get("round_nonce", 0)),
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ts=float(obj.get("ts", 0.0)),
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pass_ticket_hash=obj.get("pass_ticket_hash", ""),
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execution_hash_skim=obj.get("execution_hash_skim", ""),
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signer=obj.get("signer", ""),
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sig=obj.get("sig", ""))
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@property
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def size_bytes(self) -> int:
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return len(self.serialize())
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