Long-Term Contract Records, Provable Years Later
On 15–20 year contracts, prove cryptographically that a record legitimately existed and was legitimately amended at the time — without revealing its contents — even when amounts, specs, or inspection records are disputed years later.
🔔 Plan · Lemma Critical →For long-term contract owners
Prove years later that surviving records weren't rewritten — ending the doubt over price, spec, and whether the inspection really happened.
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Long-term maintenance / contract managers in manufacturing and critical infrastructure (power, water, transport)
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Public-sector teams accountable for ledgers and inspection records
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Teams troubled by "we have records but can't prove they're untampered" in audits or disputes
Hand over the source, or just the facts?
Change what reaches the AI, and the leakage risk goes with it.
- contract_id:
- CT-2024-08-15-001
- parties:
- Corp A, Corp B
- amount:
- 5,200,000 JPY
- terms:
- 60 months / monthly
- clauses:
- Art. 1–18 (full text)
- signatures:
- Tanaka (A CFO), Suzuki (B CEO)
- subject:
- did:lemma:contract-CT2024
- issuer:
- did:lemma:org-A-corp
- sourceHash:
- 0x9f3a…c4e8
- lineageChain:
- [draft, review, sign]
- recordedAt:
- 2024-08-15T10:23:00Z
- integrity:
- poseidon-merkle
- ZK verified:
- ✓ VALID
We anchor the moment a contract, quote, or inspection record is created. The original stays in-house (or in your current system); what leaves is only the cryptographic fact of when, by whom, under which content hash, and tamper-free it existed. Even after amendments, "it legitimately existed and was legitimately amended" can be proven without revealing the contents.
However many years later a dispute or audit arrives, the parties, auditors, and third parties verify the same proof independently — without disclosing the original data.
Choose on three criteria.
Only work that needs all three at once — pass without exposing, independent verification, tamper-proof — is Lemma's domain.
| Method | Pass without exposing | Independent verification | Tamper-proof |
|---|---|---|---|
| Access control only | △ | ✗ | ✗ |
| Masking / anonymization | △ | ✗ | ✗ |
| Encryption only | ✓ | ✗ | ✗ |
| Lemma (ZK proof)the only one with all 3 | ✓ | ✓ | ✓ |
What's next
We enter through AI-adoption and data-governance support and a PoC, and stay alongside you through to operations.
- A 30-minute review — identify records in long-term contracts/ledgers where dispute/audit risk concentrates.
- Narrow to 1–2 decisions (results) to prove — e.g. "legitimately approved/amended at this point." Not the whole ledger.
- Design connection and amendment handling — connection to existing ledger/contract systems, versioning, amendment anchoring.
- Prove one path via a (quote-based) PoC.
- Hands-on support from rollout through operations — existing plan tiers (Civic / Critical / Compliance) serve only as a cost reference; the setup and pricing are designed together.
Using the Metawater work as a template, we'll confirm in the first 30 minutes where to start anchoring in your ledgers/contracts.
The bigger picture
The bigger picture this use case belongs to.
We map use scenarios across industries and workflows by the five proofs.
See use scenarios for Verifiable Origin in Solutions →TRY LEMMA
Run it yourself.
No sales call needed — start hands-on with Lemma's products.