Ideas
“Pitch deck v1 — Skylark”
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Browser-side SHA-256 · Anchored in Bitcoin · No trusted third party
Anchor what you know, before they say you didn’t.
Drop a file or paste text. Your browser computes its fingerprint locally and stamps the fingerprint into the Bitcoin blockchain via OpenTimestamps. The original content never leaves your device. What you get back is a permanent, reproducible receipt.
Your file stays local
Only the hash is recorded
Verifiable by anyone, forever
01
How it works
Four steps. No magic.
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01
Prepare a stable document.
PDF is ideal because the bytes don’t shuffle. Any file works — the fingerprint is computed over raw bytes, not over the rendered content.
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02
Compute the fingerprint locally.
Your browser hashes the file with SHA-256 via Web Crypto. The hash is the only thing sent to ProofLedger. We never see the file’s bytes, name, or text content.
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03
Anchor the fingerprint in Bitcoin.
We submit the hash to the OpenTimestamps calendar network, which aggregates it into a Merkle tree and anchors the root in a Bitcoin block. Roughly six hours later, your proof carries a real block height.
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04
Keep the proof. Keep the original.
Verification needs both. Anyone with the original file plus the proof can recompute the hash and confirm the Bitcoin attestation independently — no ProofLedger required.
02
Transparency
What ProofLedger sees. What it doesn’t.
What we see
- The 64-character SHA-256 hash you submit.
- The title and (if you submitted one) the file name.
- An optional private note. Never shown publicly.
- The OpenTimestamps proof bytes returned by the calendar.
- Your IP, briefly, for rate-limit accounting.
What we don’t see
- The file’s bytes, contents, or text body.
- Any password, key, or identifier inside the file.
- Other documents that share the same fingerprint (there are none).
- Whether the same file has been certified elsewhere.
- Anything about who you are, unless you tell us.
03
Use cases
A short, opinionated list of what to certify.
Anywhere a date matters more than a signature. Examples are fictional but the format is real.
Predictions
“Election call — district 4”
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Research
“Hypothesis register — batch 17”
2c11e9…1f4d
Legal
“Whistleblower memo — pre-disclosure”
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Art
“Lyrics — track 03”
7a3e21…4b10
Real estate
“Move-in inventory — apt 4B”
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Personal
“Promise letter — sent unsigned”
10ef99…aa01
Digital
“Post text before deletion”
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Yours