Cloud Sync & Encryption

Sync notes across all your devices with end-to-end encryption. AES-256-GCM + Argon2id. Your passphrase, your data.

4 min read
Last updated: 4/7/2026
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Cloud Sync keeps your notes on every device. It's end-to-end encrypted - AICHE stores encrypted blobs and cannot read your data.

Setup

Cloud Sync is opt-in and off by default.

Desktop (Mac, Windows, Linux)

Open Settings > Cloud Sync > enable > set your passphrase.

iPhone / iPad

After your 2nd recording, the app prompts you to enable Cloud Sync. You can also enable it in Settings > Cloud Sync.

Android

Settings > Cloud Sync > enable > set passphrase.

Obsidian

The plugin uses encrypted local storage for offline queue. Full cloud sync follows the same passphrase.

How Encryption Works

  1. You set a passphrase on your device (never sent to the server)
  2. Your passphrase is processed with Argon2id (memory-hard key derivation) to create an encryption key
  3. Each note is encrypted with AES-256-GCM before leaving your device
  4. The server stores opaque encrypted blobs with version numbers and timestamps
  5. When syncing, your device downloads blobs and decrypts locally

AICHE never sees your plaintext data. The server cannot decrypt your notes even if compromised.

What Syncs

  • Transcriptions (text content)
  • Settings and preferences
  • Personal Dictionary entries (stored separately, not encrypted - needed server-side for transcription)

Per-Device Tracking

Each device has a unique ID. Sync tracks which devices have seen which changes. When you add a note on your phone, your desktop picks it up on next sync.

Conflict Resolution

If the same note is edited on two devices before syncing, the server keeps the newer version. Your device receives the server's version and can merge locally.

Passphrase Security

  • 5 wrong attempts = 5-minute cooldown before retrying
  • Forgot passphrase = reset option available (this deletes your synced data and starts fresh)
  • Your passphrase is never stored on the server
  • Changing your passphrase re-encrypts all synced data

Offline + Sync

When offline, recordings save locally on your device. When you reconnect:

  1. Local recordings upload for transcription
  2. Transcribed notes encrypt and sync to the cloud
  3. Other devices pull the new notes on their next sync
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