Logbook › Sealed at the Source: How a Zecboat Collection Is Made
Sealed at the Source: How a Zecboat Collection Is Made
We changed how Zecboat assets are made. Every postcard is now bound to its issuer's key, every collection's size is fixed on chain, and anyone can audit it without trusting us.
What was wrong with the old way
Our first collections used the image's fingerprint (its SHA-256 hash) as the asset's identity. That proved which picture an asset showed, but not who made it: anyone holding the image could put the same identity on a note of their own.
And how many existed was the issuer's word.
Four promises, each checkable
The collection key is the same kind of key Zcash's own asset proposal (ZIP 227) uses.
- WHO made it: every collection has its own key, and only its holder can issue
- WHAT it is: the identity binds the key to the image’s fingerprint; change one pixel and it no longer matches
- HOW MANY exist: the collection is closed on chain, and nothing issued after counts
- ANYONE can check: the issuer publishes a viewing key, and a stranger can audit everything from it
How Happy Birthday Zcash 10 was made
Each postcard is a small shielded Zcash note, 10,000 zatoshi, whose encrypted memo says which postcard it is. All ten were issued in one transaction.
- Block 3,501,212: minted. Ten postcards in one transaction.
- Block 3,501,223: closed. The issuer’s signed list of the ten is written onto the chain. No eleventh can ever count.
- Block 3,501,228: registered in the Zecboat Registry, where any wallet can find it.
The stranger's audit
Starting from nothing but the published viewing key, anyone can run 14 checks: that exactly one close exists, that the signed list rebuilds from the chain and its signature is valid, that every postcard's identity comes from the key, that nothing was issued after the close, and that every zatoshi the issuer spent is accounted for.
All three of our new collections pass all 14.
Old and new, side by side
| Before | Now | |
|---|---|---|
| The identity is | the image’s fingerprint | the collection key + the image’s fingerprint |
| Anyone can copy the identity | yes | no: only the key holder can issue |
| How many exist | the issuer’s word | closed on chain, fixed |
| How you find it | a website | the Registry, on chain |
| Who checks it | you, by hand | your wallet, one button (0.7.1) |