How Celare’s encryption works

Keys

• Each vault has its own random 256-bit master key. Everything in the vault is encrypted with keys derived from it.
• Your pattern is turned into a key with PBKDF2-HMAC-SHA256 (600,000 rounds), salted with a random value that stays on your iPhone. That key unlocks the master key. Because the salt never leaves your device, a copy of your files alone isn’t enough to guess your pattern.
• Your recovery phrase (9 words from the standard BIP39 list, about 99 bits of randomness) is turned into a second key with PBKDF2-HMAC-SHA256 (2,000,000 rounds). It also unlocks the master key, and it works on a new iPhone.
• Changing your pattern only re-wraps the master key. Your files don’t need to be re-encrypted.

Files

• Files are encrypted with AES-256-GCM in 1 MiB chunks. Each file has its own key. Each chunk is authenticated, so a chunk that’s changed, reordered or cut off is rejected.
• File names, thumbnails and the vault’s index are encrypted too. On disk, every file has a random name, and files from all vaults sit together, so nothing shows which vault a file belongs to.
• Videos are decrypted in memory as they play. Plaintext is never written to storage, with a few short-lived exceptions (exporting, previewing documents and converting video on import) that use iOS’s strongest file protection and are deleted immediately.
• Celare uses only Apple’s CryptoKit and CommonCrypto. No custom cryptography.

Hidden vaults

• Any valid pattern opens a vault. There’s no list of vaults and no “wrong pattern” message.
• The number of vault files on disk is padded with same-sized placeholders, and their timestamps are kept identical, so the storage doesn’t reveal how many vaults you have (for up to 16 vaults).

iCloud Backup

Backups upload the already-encrypted files to your own private iCloud database. Nothing is decrypted or re-encrypted on the way. Apple sees only encrypted data with random names.

What Celare can’t protect against

Being honest about limits matters as much as the features:

• Someone who sees you draw your pattern can open that vault.
• A compromised or jailbroken iPhone, or malware running on it, can see what’s on screen while a vault is open.
• On the free plan, the 3-vault limit can reveal that you have 3 vaults if someone tries to create a fourth. Pro has no limit, so it doesn’t.
• Someone who can compare your device’s storage or iCloud records over time may notice patterns in which files change. We pad and normalise what we can, but we can’t hide all activity.
• iOS keeps keys in memory while a vault is open. Celare wipes its key buffers when it locks, but the Swift language can’t guarantee every copy is erased.
• If you lose both your pattern and your recovery phrase, your data is gone. There is no backdoor, for anyone.

Questions or found an issue? support@celare.app