Custody is a three-line definition: hold the document, prove you held it, return that proof on demand. Fund Base Camp executes each line with a primitive that anyone can independently verify through the public verification system. No proprietary cryptography, no opaque database calls.
A sponsor uploads a Forward Purchase Agreement, wire receipt, pledge instrument, or subscription record through the FBC admin dashboard or REST endpoint. The bytes are streamed into per-SPV isolated storage and a SHA-256 digest is computed before the response returns. The digest is the document's mathematical fingerprint, later surfaced through the public custody verification endpoint.
The SHA-256 digest is submitted to OpenTimestamps, a free public timestamping service that aggregates submitted hashes into Merkle trees and commits their roots into Bitcoin transactions. Once the containing transaction has ≥3 confirmations, the anchor is final: undoing the timestamp would require reorganising the Bitcoin chain — an attack with an explicit, public, multi-million-dollar economic cost. Sponsors can review additional operational safeguards on the security architecture page.
Optional belt-and-suspenders: the same hash is co-anchored to an RFC 3161 timestamping authority for audiences that prefer the traditional PKI-rooted proof.
Each investor and each sponsor receives a Fund Base Camp transaction code at subscription, with the form FBC-[series]-[role]-[ticket]. The code is opaque — it encodes no personally-identifying information, no document content, no balance, nothing that could leak in a screenshot. It is only an index into the custody table on the verification server.
Codes are case-insensitive, fixed-length, and printable. They can be embedded in subscription confirmations, signed PPM appendices, custodian receipts, or scanned QR labels.
Anyone holding a transaction code can submit it at fundbasecamp.com/verify or query the public API at /api/v1/verify/{code}. The response is the structural custody record: the SPV, the documents in custody, each document's SHA-256, the anchor reference, and the date of the most recent independent attestation. No PII is returned; the queries themselves are not retained beyond standard rate-limit accounting.
The same response is available as a downloadable receipt PDF for offline keeping and long-term investor record retention through the document custody framework.
{
"code": "FBC-26A-INV-0042",
"spv": "Limen Markets Series 2026-A LLC",
"docs": [
{ "title": "Forward Purchase Agreement",
"sha256": "8f3c4e21…b7d6f5",
"deposited": "2026-06-12T18:04:11Z" },
{ "title": "Wire receipt", "sha256": "2d7e9a1c…f9b2e5d", "..." }
],
"anchor": {
"service": "OpenTimestamps",
"chain": "bitcoin",
"block": 891204,
"txid": "3a9f…4f01",
"confs": 6
},
"attestation": "2026-Q2 AUP · Lukas & Co. CPAs",
"status": "VERIFIED"
}
What this design avoids. No proprietary hash function, no Fund-Base-Camp-controlled timestamp service, no custodial signature scheme, no requirement to trust Fund Base Camp's database. Every claim made by the verification page can be checked against a public artifact — the Bitcoin blockchain — by anyone who downloads the proof file.
Two commands. A document. An .ots proof file. Anyone can do this on any machine, offline, without contacting Fund Base Camp at all through the public verification workflow.
If the sponsor has delivered the document to you, hash it locally and compare to the value returned by the verification page. Any difference indicates the document has been altered since deposit.
Fund Base Camp publishes the .ots proof artifact for each document. Anyone can verify it against the Bitcoin blockchain using the open-source OpenTimestamps client.
The verification page produces a downloadable PDF receipt containing the full custody record, the anchor reference, and instructions for re-verifying offline. Keep it with your subscription documents.
The receipt is self-contained: an investor can re-verify everything in it years later, even if Fund Base Camp's verification API is offline, by re-hashing the document and checking the included .ots proof against any Bitcoin full node.
/verify endpointSponsors who run their own investor portals can embed verification by calling the public verify endpoint. Authentication is not required; rate limits apply per IP. No PII is accepted or returned.
GET https://fundbasecamp.com/api/v1/verify/{code} # curl example $ curl https://fundbasecamp.com/api/v1/verify/FBC-26A-INV-0042 { "code": "FBC-26A-INV-0042", "spv": "Limen Markets Series 2026-A LLC", "underlying": "Space Exploration Technologies Corp.", "role": "investor", "deposited": "2026-06-12T18:04:11Z", "documents": [ { "title": "Forward Purchase Agreement", "sha256": "8f3c4e21a9b7d6f5e8c1a4b7d6f5e8c1a4b7d6f5e8c1a4b7d6f5e8c1a4b7d6f5", "size_bytes": 184221 }, { "...": "..." } ], "anchor": { "service": "opentimestamps", "chain": "bitcoin", "block": 891204, "txid": "3a9f…4f01", "confirmations": 6, "anchored_at": "2026-06-12T18:43:51Z", "proof_url": "https://fundbasecamp.com/proofs/FBC-26A-INV-0042.ots" }, "attestation": { "period": "2026-Q2", "firm": "Lukas & Co. CPAs", "published": "2026-04-15", "report_url": "https://fundbasecamp.com/security#aup" }, "status": "VERIFIED" }
Want to integrate? Email engineering@fundbasecamp.com for API keys (only required for ingestion endpoints, not verification) and review the sponsor integration overview for deployment workflows and custody onboarding.