Re: Per-identity subdomains for Nostr storage (XSS isolation)

Library: https://github.com/nostrapps/bech32-label

Demo: https://nostrapps.github.io/bech32-label/

pá 8. 8. 2025 v 18:16 odesílatel Melvin Carvalho <melvincarvalho@gmail.com>
napsal:

> Hi all,
>
> To reduce cross-tenant XSS/CSRF risk, I’d like to standardize a simple
> per-identity subdomain convention so each user’s data lives on its own
> origin (separate cookies, localStorage, Service Workers, caches).
>
> Proposal:
>
> Input: 32-byte Nostr pubkey.
>
> Encoding: bech32 data-only (same alphabet as npub), no HRP, no checksum.
>
> Rule: convert 8→5 bits MSB-first with zero-padding; map to the bech32
> charset; result is exactly 52 lowercase chars.
>
> Usage: <52-char-label>.<provider-domain> as the storage origin.
>
> Why not other encodings?
>
> 64-char hex can’t be a single DNS label—label max is 63, so it’s one
> character too long.
>
> Full npub… is display-friendly but not ideal as a normative origin ID. It
> carries an HRP/checksum that isn’t tied to cryptographic versioning (e.g.,
> bech32 vs bech32m / taproot semantics), so it’s not future-proof. Perhaps
> best treated as UI display only.
>
> Benefits: deterministic, DNS-safe, reversible, widely familiar to the
> Nostr community (same bech32 alphabet), and easy to implement
> consistently—satisfying the Test of Independent Invention.
>
> If there’s interest, I can share a tiny draft (spec + test vectors + JS
> helper) for review.
>
> Best,
> Melvin
>