Observed arrival · 2026-09-26
The cat is inside the Zcash transaction
ZCAT is a browser demo that uses a published Zcash viewing key to decrypt and reassemble an image embedded in a shielded payment.
○Open
⊠Login
$Paid
†Ads
✦Pretty
●Pro
◎Niche
◉Human
⚑Risk
ƒJS
- For
- Zcash users and privacy-technology tinkerers
- Worth noticing
- The image is split across 19 512-byte memo parts; a deliberately different viewing key demonstrates that the decryption is key-dependent.
Field notes
The page lays out a three-step browser workflow: fetch the public transaction from Blockchair, try the published read-only viewing key against its 20 encrypted parts, then sort and join the 19 parts that open. It says the image bytes occupy Zcash shielded-payment memo data in 19 chunks of 512 bytes, and that a fingerprint check is applied before display. A “Use someone else’s key” control provides a negative test; the page says processing stays in the browser.
Observed signals
Read the marks
Editorial observations of this landing page, not a rating.
○OpenPublic substance visible
✦PrettyNotable craft visible
●ProPolished or operationally mature
◎NicheUnusually specific use
One card from the complete issue