Vitnify your agents

Logs tell you what your agent did. Vitnify proves it — a cryptographic, independently-reconstructable record of what an agent computed and did.

Contain what an agent may do, deterministically reconstruct the model behind every decision, and seal the whole run into one bit-for-bit receipt anyone can verify offline — long after it happened.

vitnify (v.) — to turn an agent run into a receipt anyone can reproduce and verify, offline.

vitnify isn't detection. It gives you the primitives to prove exactly what an agent did: a vitnify-receipt v2 binds the model's computation, the granted capabilities, every tool call and result, the entropy, and the order into a single ed25519-signed, self-verifying object.

Install

pip install vitnify

Quickstart

from vitnify.events import EventLog, Kind
from vitnify.engine import Engine, prompt_hash
from vitnify.certificate import issue_certificate, verify_authorized, gen_ed25519

eng = Engine("model.gguf", model_id="my-model")        # deterministic backend
log = EventLog()

step = eng.run(prompt_tokens=[1, 2, 3], n_new=20)       # a model step
log.append_llm_call(prompt_hash([1, 2, 3]), step["tokens"], seed=0,
                    model_digest=step["model_digest"],       # bind the model computation
                    regime=step.get("regime"),               # + regime and weights_hash: bound in the
                    weights_hash=step.get("weights_hash"))   #   digest, now readable in the receipt too
log.append(Kind.TOOL_CALL, {"tool": "read_docs",  "decision": "allow"})
log.append(Kind.TOOL_CALL, {"tool": "send_email", "decision": "deny"})  # ungranted → blocked

priv, pub = gen_ed25519()
cert, _ = issue_certificate("program_hash", ["read_docs"], log, priv=priv)

checks = verify_authorized(cert, log, pinned_pubkeys=[pub])  # L1: offline, no model/secret; authorised signer
assert checks["ok"]                       # signed by a trusted key, unaltered, no ungranted tool ran
assert checks["containment_enforced"]     # every tool call was GATED, not merely observed
# A receipt can be ok=True yet containment_enforced=False — a valid transcript from a
# watch-only integration proves what ran, not that anything was contained. A containment
# claim requires BOTH. (level 2: re-run each step through the engine; every model_digest
# reproduces bit-for-bit.)

See the receipt format spec (canonical — this repo does not vendor a copy, so the two can't drift), and examples/demo_receipt_e2e.py for the full loop.

What you get

• Capability containment — ungranted tools are structurally unreachable.
• Deterministic replay — re-run a contested run and get the identical result, bit-for-bit.
• Bit-for-bit receipts — the model's exact computation, bound and signed.
• Redaction by default — the Broker commits salted hashes of tool payloads instead of cleartext, on allow and deny, so PHI/secrets never enter the receipt; cleartext stays in an org-held Vault, disclosed one event at a time with an inclusion proof (vitnify.redact). Pass allow_cleartext=True for the old behaviour (non-sensitive data only).
• Offline verification — anyone verifies a receipt's integrity (integrity_ok) with no model, network, or secret; authority (that an approved runtime signed it) is a separate verdict that needs a pinned trust root.
• Drop-in — wraps existing LangGraph and MCP agents (pip install vitnify[langgraph] / [mcp]).

Two verification levels — and when to use each. Level 1 (integrity) is offline, instant, and needs no model — recompute the Merkle root and check the signature; this is the default for every receipt, and it's what proves containment and tamper-evidence. Level 2 (recompute) additionally re-runs the model to reproduce the committed logits. It is the dispute path — run on a contested subset when someone challenges a specific decision, not on every receipt inline. It is deliberately slow: the pinned-order deterministic engine trades throughput for bit-exactness, roughly two orders of magnitude below native inference (~0.45 tok/s vs ~58 for Mistral-7B Q4_K_M on the same Metal box). Fleet throughput still scales the normal way — L2 is embarrassingly parallel across receipts; a single recompute is simply not something you do on the hot path.

The verdict is split (0.4.1) — a receipt answers two different questions, and a verifier reports them separately instead of collapsing them into one boolean:

• integrity_ok — is the transcript internally consistent and validly signed by whoever signed it? Answerable by anyone, offline, no secret. Tampering, a forged chain, an ungranted tool, a bad signature all set it False.
• authority_ok — was the signer an approved runtime? Needs a trust root, so it is True / False / None (unestablished when no anchor is supplied — a stranger offline can never answer it, and is told so rather than given a bare False that looks forged).
• ok = integrity_ok and an authorised signer. Pin the trusted key(s) — verify_authorized(cert, log, pinned_pubkeys=…) is the production entry point; anchor it in a TPM/enclave for the strongest form. Pass require_authority=False to make ok the integrity-only verdict (the answer a stranger can compute offline).

Program binding. program_hash is caller-asserted unless you bind it. Pass derive_program_hash(paths_or_bytes) at issue time and verify_certificate(..., program=…) at verify time to make the receipt bind the actual program, not a label.

✅ Safe by default (0.4.0)

The Broker redacts (no tool payload enters the receipt) and verify_certificate requires signer authority (a re-signed forgery can't verify without a trusted pin). Relax either only where appropriate, and do it explicitly:

broker = Broker(caps, tools, log, allow_cleartext=True)   # record payloads in cleartext (non-sensitive only)
verify_certificate(cert, log, require_authority=False)    # integrity-only verdict (continuity, not authority)

The production verify pins the trusted signer(s) and can bind the program:

from vitnify.certificate import verify_authorized, derive_program_hash
cert, _ = issue_certificate(derive_program_hash(SRC), caps, log, priv=priv)  # bind the real code
checks  = verify_authorized(cert, log, pinned_pubkeys=[trusted_key], program=SRC)  # authority + binding

The deterministic engine is vitni-tensor; the vitni-receipt binary is the model backend (point VITNI_RECEIPT_BIN at it).

License

Apache-2.0. "vitnify" and "vitnify-verified" are trademarks — see TRADEMARKS.md. A fork may use the code, but not the name or issue vitnify-verified receipts.

Part of Vitnify

This SDK is one of three open repos:

• vitni-tensor — the deterministic, no_std engine that produces the bit-identical model-computation digest this SDK binds.
• vitnify-receipt-spec — the canonical vitnify-receipt v2 format the SDK implements.
• vitnify.com — the project.