The proof layer
just got stronger.
ProofLink v3 is live — ML-DSA-65 FIPS 204 post-quantum signing added across seven named agent identities (iself, ag2, hermes, octoai, prooflink, rollback, itsloop), built on Ed25519 · W3C VC envelopes · JCS RFC-8785 · Bitcoin OTS. Five independent proof mechanisms.
Six improvements.
Every new receipt benefits immediately.
ProofLink v1 established the SHA-256 hash chain and Bitcoin anchoring that has produced 90,000+ tamper-evident, independently verifiable receipts. v2 adds a second, independent cryptographic proof layer — Ed25519 digital signatures — without touching the existing chain.
Ed25519 Signing — All Paths
Every new receipt is signed with Ed25519 across all three seal paths: append.py, ops-api/sealer.py, and sie/receipts.py. Previously only the CLI path signed.
Consistency fixJCS Strict RFC-8785
canonical_bytes now uses strict RFC-8785 JSON Canonicalization Scheme via the jcs package. Byte-for-byte deterministic across all implementations and languages.
NewW3C Verifiable Credential Envelope
Every v2 receipt is wrapped in a W3C VC JSON-LD envelope. Any VC-compatible verifier — including DIF, W3C, and enterprise identity systems — can now verify ProofLink receipts natively.
NewTamper Detection on Verify
The verify endpoint now re-derives canonical_bytes from stored receipt fields and compares against the stored value. Any field modification after sealing is immediately detected.
NewReceiver Attestation
v2 receipts support receiver_attestation — a second signature from the entity receiving the action proof. Enables multi-party accountability without a central ledger authority.
NewForward-Only Policy · Locked
90,000+ v1 receipts remain exactly as sealed. No backfilling. No retroactive modification. The Bitcoin OTS anchors on those receipts are permanent and provable independently of iTechSmart.
PolicyWhat a v2 receipt
looks like.
Every field serves a specific regulatory or cryptographic purpose. No field is decorative.
{
"schema_version": "2.0", // v2 flag — triggers sig validation
"receipt_id": "heal-api-gateway-20260618",
"timestamp": "2026-06-18T02:14:33.441Z",
"actor": "iSELF v1.0 / itechsmart-agent-07",
"action": "restart_service",
"subject": "itechsmart-api.service",
"outcome": "SUCCESS — service healthy in 8.2s",
// v1 fields — unchanged, chain compatible
"hash_sha256": "a445bd9dfe747b3e...", // SHA-256 of content (OTS anchors this)
"prev_hash": "e8b9aea67e5bbe73...", // chain link to predecessor
"bitcoin_tx": "4/4 OTS calendars confirmed",
// v2 cryptographic fields — new
"canonical_bytes": "<JCS RFC-8785 canonical JSON bytes>",
"signature": {
"algorithm": "Ed25519",
"public_key": "<32-byte hex — platform signing key>",
"value": "<64-byte hex — sig over canonical_bytes>"
},
// W3C Verifiable Credential fields
"vc_context": ["https://www.w3.org/2018/credentials/v1", "https://prooflink.itechsmart.dev/schema/v2"],
"vc_type": ["VerifiableCredential", "AIActionReceipt"],
"compliance_mappings": {
"nist_ai_rmf": ["GOVERN-1.1", "MAP-2.1", "MEASURE-2.5"],
"eu_ai_act": ["Article-12(1)", "Article-12(2)", "Article-12(4)"],
"soc2": ["CC7.2", "CC7.3"]
},
"scitt_compatible": true,
// Optional: second-party attestation
"receiver_attestation": {
"receiver": "verify.itechsmart.dev",
"signed_by": "<receiver Ed25519 public key>",
"signature": "<receiver sig over {receipt_id, timestamp}>",
"timestamp": "2026-06-18T02:14:35.001Z"
},
"verify_url": "https://verify.itechsmart.dev/r/heal-api-gateway-20260618"
}
canonical_bytes — the JCS-canonical JSON of the receipt content fields present at signing time. Bitcoin OTS anchors hash_sha256 — the SHA-256 of the same content. Five independent proof mechanisms: SHA-256 hash chain, ML-DSA-65 FIPS 204 post-quantum signature, Ed25519 signature, W3C VC envelope, Bitcoin OTS anchor. Neither depends on the other. Both are verifiable without access to iTechSmart's systems.
Three receipt types.
All verifiable at verify.itechsmart.dev.
The verifier handles all receipt generations backward-compatibly. No receipt ever becomes unverifiable.
v2 satisfies every logging
mandate we know of.
ProofLink v2 was designed against EU AI Act Article 12, HIPAA audit controls, NIST AU, and SOC2 CC7.2 simultaneously.
| Requirement | v1 Coverage | v2 Addition | Status |
|---|---|---|---|
| EU AI Act Art. 12(1) Automatic logging | SHA-256 + append-only ledger | Ed25519 signature on every seal path | EXCEEDS |
| EU AI Act Art. 12(2) Traceability | Hash chain + prev_hash | Tamper detection re-derives canonical_bytes | EXCEEDS |
| EU AI Act Art. 12(3) Monitoring | Public verify.itechsmart.dev | W3C VC — any VC verifier works | EXCEEDS |
| EU AI Act Art. 12(4) Retention | Bitcoin OTS — permanent | No change needed — already permanent | EXCEEDS |
| HIPAA 45 CFR 164.312(b) | Immutable audit log | Non-repudiation via Ed25519 | COMPLIANT |
| NIST SP 800-53 AU-9 | Append-only protection | Cryptographic tamper detection | COMPLIANT |
| SOC2 CC7.2 System Monitoring | ProofLink chain | Verifier integrity checks | COMPLIANT |
| W3C Verifiable Credentials | Not supported | Full VC JSON-LD envelope | COMPLIANT |
| SCITT (IETF draft) | Not supported | scitt_compatible: true on all v2 receipts | READY |
How we got here.
Verify a receipt right now.
The entire ledger is public. Every receipt — v1 and v2 — is independently verifiable without access to iTechSmart's systems.