3dtours
8a889db069
A photo's landing section can now be the QR card, and that section is the only one that hands something out: the server writes the photo's own stored look back as the app's .recipe file, at GET /api/photos/:id/preset.recipe, for any row the curator ticked into the qr slot. Nothing new is stored — the file is built from the recipe the upload already carried, so it works for a photo uploaded by the phone too. The admin pane grows a fourth checkbox and a fourth row (QR card); the row draws the download link as a scannable code, and the box is dead for a photo with no stored look. The landing's QR card now encodes the curated photo's own link instead of a mock address. The listing exposes hasPreset, never the recipe itself.
59 lines
2.2 KiB
TypeScript
59 lines
2.2 KiB
TypeScript
// The `.recipe` file the app writes on EXPORT and reads back on IMPORT. It is a
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// small XML envelope around a scrambled hex payload, and the landing page's QR
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// card hands a photo's look back as exactly this file, so the server has to
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// write the app's own format. The source of truth is the web app's
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// `shared/utils/recipeShare.ts`; this module and the phone app's
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// `src/utils/recipeShare.ts` are its copies, and `test/security.mjs` pins the
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// envelope's shape. Change all three together, or the QR stops importing.
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//
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// ponytail: obfuscation, not cryptography — the key ships inside the app. Same
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// caveat as the app's copy: swap in a real cipher at these two functions if the
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// envelope ever has to resist a determined reader.
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const KEY = 'RecipesCam::recipe-share::v1';
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const ALGORITHM = 'xor16-v1';
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const hash = (s: string): number => {
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let h = 0x811c9dc5;
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for (let i = 0; i < s.length; i++) {
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h ^= s.charCodeAt(i);
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h = Math.imul(h, 0x01000193);
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}
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return h >>> 0;
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};
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// xorshift32: one 16-bit word of keystream per call.
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const stream = (seed: number) => {
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let s = seed >>> 0 || 0x9e3779b9;
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return () => {
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s ^= s << 13;
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s >>>= 0;
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s ^= s >>> 17;
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s ^= s << 5;
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s >>>= 0;
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return s & 0xffff;
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};
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};
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// 16-bit code units, hex-encoded: no encoder needed, every UTF-16 char (names
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// with Vietnamese diacritics included) survives the round trip.
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const scramble = (text: string, salt: number): string => {
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const k = stream(hash(`${KEY}|${salt}`));
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let out = '';
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for (let i = 0; i < text.length; i++) out += (text.charCodeAt(i) ^ k()).toString(16).padStart(4, '0');
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return out;
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};
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// The recipe as the app stored it, wrapped in the envelope. The payload is the
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// stored JSON whole: the parser on the other side keeps the fields it knows and
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// drops the rest, so this side needs no opinion about what a recipe contains.
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export function recipeFile(recipeJson: string): string {
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const salt = Math.floor(Math.random() * 0xffffffff) >>> 0;
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return [
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'<?xml version="1.0" encoding="UTF-8"?>',
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`<recipescam-recipe version="1" algorithm="${ALGORITHM}" salt="${salt.toString(16)}">`,
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` <payload>${scramble(recipeJson, salt)}</payload>`,
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'</recipescam-recipe>',
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'',
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].join('\n');
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}
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