owned product through uxuiai.org · live · verified 2026-07-27
Cinder
Most private note services encrypt on their own server, which means the operator can read what was sent.
the meaningful constraint
Browser-side encryption, an atomic one-time delivery, least-privilege AWS roles, accessibility, and an honest account of the limits all have to hold at once.
the smallest consequential decision
Keep the key in the URL fragment where no server ever receives it, delete the stored copy and verify its absence before any response byte exists, and publish what Cinder cannot protect beside what it can.
implementation depth
- SvelteKit and Svelte 5
- Web Crypto AES-256-GCM in the browser
- AWS Lambda, DynamoDB, S3, and CloudFront
- published threat model, with unit, API, and browser test layers covering the security claims
what shipped or remains public
A live zero-knowledge service for a one-time note or a single encrypted file up to 4 MiB, where receiving the bytes is itself proof the stored copy was already deleted.
privacy relevance
Encryption and decryption happen in the browser and the key never reaches a server; Cinder stores ciphertext only, and it states plainly that it cannot protect a compromised device, a leaked link, metadata, or copies someone already kept.
accessibility relevance
The whole journey is reachable without a mouse or a screen: every outcome is announced, focus follows each view change, and a 2.57:1 button label measured in light mode was fixed before release.
correction path
If this public evidence has changed, email a correction for this record.