66 lines
2.1 KiB
JavaScript
66 lines
2.1 KiB
JavaScript
// Content-addressable hashing for GEP assets.
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// Provides canonical JSON serialization and SHA-256 based asset IDs.
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// This enables deduplication, tamper detection, and cross-node consistency.
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const crypto = require('crypto');
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// Schema version for all GEP asset types.
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// Bump MINOR for additive fields; MAJOR for breaking changes.
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const SCHEMA_VERSION = '1.5.0';
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// Canonical JSON: deterministic serialization with sorted keys at all levels.
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// Arrays preserve order; non-finite numbers become null; undefined becomes null.
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function canonicalize(obj) {
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if (obj === null || obj === undefined) return 'null';
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if (typeof obj === 'boolean') return obj ? 'true' : 'false';
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if (typeof obj === 'number') {
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if (!Number.isFinite(obj)) return 'null';
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return String(obj);
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}
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if (typeof obj === 'string') return JSON.stringify(obj);
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if (Array.isArray(obj)) {
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return '[' + obj.map(canonicalize).join(',') + ']';
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}
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if (typeof obj === 'object') {
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const keys = Object.keys(obj).sort();
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const pairs = [];
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for (const k of keys) {
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pairs.push(JSON.stringify(k) + ':' + canonicalize(obj[k]));
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}
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return '{' + pairs.join(',') + '}';
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}
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return 'null';
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}
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// Compute a content-addressable asset ID.
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// Excludes self-referential fields (asset_id itself) from the hash input.
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// Returns "sha256:<hex>".
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function computeAssetId(obj, excludeFields) {
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if (!obj || typeof obj !== 'object') return null;
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const exclude = new Set(Array.isArray(excludeFields) ? excludeFields : ['asset_id']);
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const clean = {};
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for (const k of Object.keys(obj)) {
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if (exclude.has(k)) continue;
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clean[k] = obj[k];
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}
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const canonical = canonicalize(clean);
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const hash = crypto.createHash('sha256').update(canonical, 'utf8').digest('hex');
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return 'sha256:' + hash;
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}
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// Verify that an object's asset_id matches its content.
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function verifyAssetId(obj) {
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if (!obj || typeof obj !== 'object') return false;
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const claimed = obj.asset_id;
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if (!claimed || typeof claimed !== 'string') return false;
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const computed = computeAssetId(obj);
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return claimed === computed;
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}
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module.exports = {
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SCHEMA_VERSION,
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canonicalize,
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computeAssetId,
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verifyAssetId,
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};
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