EU AI Act Article 12 · enforcement 2 Aug 2026

Court-admissible cryptographic evidence for AI agents.

Open-source SDK that signs every agent step. Hourly Merkle commitments, RFC 3161 timestamps, claim packs you can hand to an underwriter or a court. Verifiable offline — no expert witness, no hardware vendor in the trust chain.

Court-admissible Offline-verifiable Hardware-free No US vendor in trust chain Apache 2.0 SDK + verifier SCITT-aligned
Why AgentSig

Three properties that matter for court-admissible evidence.

Every cryptographic primitive is battle-tested IETF / NIST. The differentiation is architectural — what the evidence chain doesn't depend on.

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Court-admissible by design

The verifier is Apache 2.0. Your team, your auditor, the opposing party in a dispute can all run the same code and reach the same conclusion. No "trust us, the binary says VERIFIED" black box. No expert witness required to explain hardware attestation chains.

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Offline-verifiable

Claim packs verify without internet — no callbacks to AgentSig infrastructure, no calls to third-party attestation services. Sealed evidence in three years still verifies the same way. One CLI command runs eight independent cryptographic checks.

🌍

No hardware vendor lock-in

DID-based identity (W3C did:web) — your domain is the trust root, not a US certificate authority. Runs on any cloud or on-prem; no TEE silicon required. EU-friendly anchoring options for DORA / Schrems III conscious deployments.

Working today

See it run end-to-end.

Three commands produce a court-admissible claim pack and verify it offline. The output below is a real run — Ed25519 signatures, RFC 3161 timestamp from a public TSA, Merkle inclusion proofs, all checked.

$ python -m cli.sign --count 10 --out data/envelopes/
Generated 11 envelope(s). Signing public key written.
 
$ python -m cli.merkle_build --envelopes data/envelopes/ --out data/build/
envelopes loaded: 11
merkle root: 70e2ac090294e3fdd0b4d44de758c3f8...
STH signed: 211 B
TSA request: RFC 3161 ... (4644 B token)
receipts written: 11
Claim pack: data/build/claim-pack-demo-001.zip
 
$ python -m cli.verify data/build/claim-pack-demo-001.zip
Envelopes seen: 11
Ed25519 valid: 11/11
CBOR shape valid: 11/11
Chain valid: 11/11
Counter monotonic: 11/11
DAG closed: 11/11
STH signature:
Inclusion proofs: 11/11
TSA timestamps: 1/1 structurally valid
 
VERIFIED ✓

Quickstart on GitHub

Battle-tested cryptography only

No custom crypto. Standards-aligned.

Every primitive is IETF or NIST. Every choice is what auditors and regulators already accept as evidence.

Signatures
Ed25519
RFC 8032
Envelope
COSE_Sign1
RFC 9052
Serialization
CBOR
RFC 8949
Hashing
SHA-256
FIPS 180-4
Authenticated MAC
HMAC-SHA-256
RFC 2104
Encryption
AES-256-GCM
NIST SP 800-38D
Timestamping
RFC 3161 TSA
Diversity pool
Identity
W3C DID Core
did:web + did:key
Transparency
IETF SCITT
SCITT-aligned
Observability
OpenTelemetry
GenAI semconv
Post-quantum
ML-DSA-65
FIPS 204 (slot reserved)
Compliance
EU AI Act Art. 12
ISO 42001 §9
Built for these use cases

Evidence that fits the audit cycle of the AI insurance market.

Not a generic developer tool. AgentSig produces evidence in formats already accepted by insurance underwriting, regulatory audits, and civil dispute resolution.

AI insurance underwriting
Claim adjudication evidence — what the agent did, when, signed by the operator, anchored externally.
AI agent certification audits
Pre-validated cryptographic evidence shrinks the manual review workload of accountability-domain controls.
EU AI Act enforcement
Article 12 (logging) + Article 26 (deployer obligations, six-month retention). Verifier runs offline by national authorities.
Civil dispute resolution
Court-admissible evidence chain — opposing parties verify with the same open-source CLI, no expert witness needed.
ISO 42001 §9 evidence
Monitoring, measurement, analysis and evaluation requires tamper-evident records. Cryptographic chain meets the bar.
Cross-org A2A trust
Dual-signed receipts between organizations — neither party can later repudiate. No shared trust authority required.
Early stage · design-partner conversations open

Let's see if the evidence pack fits your audit cycle.

30-minute walkthrough. Working claim pack on a real agent workload. Your team runs the open verifier. If it doesn't help your audit or claim-adjudication workflow, we walk away — no contract, no cost.

Request 20-min demo Read the code