安全Security
凭证的归宿，是系统钥匙串。
安全模型
- 私钥存入系统钥匙串，受设备解锁保护、不以明文落盘。
- 密码与可同步密钥经 iCloud 钥匙串端到端加密，连 Apple 也读不到。
- 主机指纹 TOFU 校验——首次信任、之后变更即拦截（防中间人）。
- 启动生物识别解锁；复制后自动清空剪贴板。
- 所有配置本地存储，离线可用、无需账号。
与同步的关系
同步默认关闭；开启后配置与凭证分轨上云，敏感数据仍不落明文库。完整说明（同步哪些、不同步哪些、iCloud 与第三方两种方式）见 多端同步。
Credentials belong in the system Keychain.
Security model
- Private keys go into the system Keychain — protected by device unlock, never written in plaintext.
- Passwords and syncable keys are end-to-end encrypted in the iCloud Keychain, unreadable even to Apple.
- TOFU host-fingerprint checks — trust on first use, block on change (anti-MITM).
- Biometric unlock on launch; clipboard auto-clears after copy.
- All config stored locally — works offline, no account.
How this relates to sync
Sync is off by default. When you turn it on, config and secrets travel on separate tracks — never as plaintext in the config store. See Multi-device Sync for what syncs, what doesn’t, and the iCloud vs third-party options.