How Cryptograph Works

From request to signature

The iPhone displays the portfolio, prepares unsigned requests, handles networking, and relays data. It does not hold the mnemonic or private spending keys.

Apple Watch holds the signing material. Cryptograph decodes each request on the watch, displays the consequential details, and requires approval there before producing a signature.

A compromised iPhone can expose public wallet information, prepare a malicious request, or try to mislead you. It cannot produce a signature. Review the details shown on Apple Watch before approving.

Why Apple Watch?

• A separate surface: Apple Watch has no Safari app. Cryptograph keeps signing material on a separate device, outside the iPhone's browser, message, and third-party app surface.
• Already with you: Approval happens on a device worn on the wrist, without another object to carry or retrieve.
• No purchase record with Cryptograph: The app is sold through Apple's App Store. Cryptograph requires no account and receives no customer name or shipping address.
• A familiar form: An Apple Watch does not announce a dedicated crypto device in a pocket, bag, or hotel room.
• Physical controls: A watch passcode and wrist detection are required. Time Lock can add delays and location-aware spend limits.

What You Trust

• Apple Secure Enclave: Hardware-isolated chip on the watch that stores the encryption key for your mnemonic. The key cannot be exported.
• Cryptograph's implementation: The wallet software that generates keys, builds transactions, and manages signing. Security-critical code is open source.
• App Store distribution: The app is delivered through Apple's App Store. No sideloading, no direct downloads.

Cryptograph's signing architecture does not depend on a company-held key or custody service. Network access and market data still travel through external infrastructure. The watch remains the signing authority, and approval on the watch remains essential.

Recovery

• Backups are encrypted on the watch before any data reaches the phone
• The phone never sees plaintext recovery data. It handles only opaque ciphertext
• Encryption: PBKDF2 (1,000,000 iterations) + ChaCha20-Poly1305, secured with a PIN or passphrase you choose on the watch
• Existing wallets can be imported from 12 or 24 BIP39 words; the advanced 24-word flow also supports a BIP39 passphrase
• BIP39 passphrases are limited to 1–50 printable ASCII characters with no leading, trailing, or repeated spaces. Why Cryptograph uses this stricter profile
• For a Cryptograph-generated wallet, your Recovery Sheet or Photo Backup is the intended way to restore after losing the watch
• Loss of both the watch and every recovery copy is permanent. There is no backdoor, server recovery, or override

Cryptograph requires you to create and verify a backup during initial setup. There is no "skip" button.

Supply Chain Security

• Updatable wallets require trust: A compromised update can misuse legitimate key-access paths during normal use. This is true for any wallet with updatable software or firmware.
• The update mechanism is the security boundary: A hardware wallet is only as trustworthy as its latest firmware update. The device itself is not the boundary; the update path is.
• Complexity expands the attack surface: A hardware wallet includes firmware, companion apps, update channels, and dependencies. Every layer increases the trusted computing base. Complexity is a security liability.
• Cryptograph keeps the critical path narrow: Keys remain on Apple Watch. Signing happens on the watch. There is no backend custody and no large host application required to manage keys.
• Independent distribution adds friction: Cryptograph is distributed through Apple's App Store, an independent third party that reviews updates. This is friction, not a guarantee, but it requires an attacker to compromise both the developer and pass external review.
• Small, inspectable code surface: Cryptograph is implemented as native code with a deliberately small dependency surface. Security-critical components are open source. The goal is not to eliminate trust, but to make it visible and easier to reason about.

Limits

• Compromised updates: Any updatable wallet must trust its update mechanism. If an attacker compromises the developer's build pipeline, a tampered version of the app can misuse legitimate key-access paths and exfiltrate secrets. Secure Enclave protects keys at rest, not against a compromised version of the app at runtime. Cryptograph reduces this risk by keeping key use narrow and visible, distributing through Apple's App Store (independent friction), and making security-critical code publicly inspectable.
• Apple platform compromise: A fundamental breach of the Secure Enclave or watchOS is out of scope. Cryptograph trusts Apple's hardware security.
• Lost recovery material: If you lose your watch and your Recovery Sheet or Photo Backup, your funds are permanently inaccessible.
• Physical coercion: Time Lock imposes delays and spend limits, but sustained coercion longer than your configured delay can eventually overcome it.

For the full technical analysis, see the Technical Security Overview.