WebCrypto SHA-256 完整性校验与去重持久化

`title: WebCrypto SHA-256 完整性校验与去重持久化``categories: Web 开发/前端/数据管理``keywords: WebCrypto,SHA-256,完整性,去重,IndexedDB,OPFS``description: 使用 WebCrypto 计算 SHA-256 对资源与文件进行完整性校验，并以哈希索引实现去重持久化，减少重复存储与传输。`计算哈希async function sha256(bytes) { const digest = await crypto.subtle.digest('SHA-256', bytes); return Array.from(new Uint8Array(digest)).map(b => b.toString(16).padStart(2, '0')).join(''); } 去重写入async function dedupPut(db, name, bytes) { const hash = await sha256(bytes); // 查询是否已有同哈希记录 const exists = await hasHash(db, hash); if (exists) return { skipped: true, hash }; const root = await navigator.storage.getDirectory(); const handle = await root.getFileHandle(name, { create: true }); const writable = await handle.createWritable(); await writable.write(bytes); await writable.close(); await putMeta(db, { id: crypto.randomUUID(), name, hash, size: bytes.byteLength, ts: Date.now() }); return { skipped: false, hash }; } 索引与查询IndexedDB 以 `hash` 建索引，快速检测重复；读取时校验一致性并修复损坏。