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That cannot work for all the payment cards etc you have right? That data never leaves the secure chip on your phone, I hope?

DaiPlusPlus 3y ago
The iPhone transfers card details to Apple Watch automatically, so no, that data is not stored in a non-exportable fashion. The data-storage capacity of things like a TPM or Apple's secure enclave is absolutely tiny (e.g. the TPM specification[1] only requires ~7KiB) - which makes sense considering it only needs to store a handful of encryption keys and other stored-secrets. [1]https://trustedcomputinggroup.org/resource/pc-client-platform-tpm-profile-ptp-specification/ https://trustedcomputinggroup.org/resource/pc-client-platfor...
- iancarroll 3y ago
  Payment cards aren’t transferred to Apple Watch automatically. The enrollment process occurs again and the watch receives its own unique card number. The iPhone does allow you to initiate the enrollment for your Apple Watch without entering the card number again, you just need to re-enter the CVV.
- rendx 3y ago
  The actual TPM storage may be tiny, but you can use it to encrypt and decrypt arbitrary amounts of data. All the TPM needs to hold is the key. That you can actively ask it to transfer data to the Watch or Cloud doesn't automatically mean that it is not using the TPM for storing that data at rest, requiring the phone to be unlocked for any such transfer.
- eightyfive 3y ago
  Cards on an Apple Watch are provisioned separately from those on a paired phone. They have different card numbers, and are provisioned as two separate passes, each with its own fraud control. Once a pass has been added to one Apple device, a reference token to that physical card is added to your iCloud account, which can be used to initiate the provisioning flow on other devices. Usually that token requires at least a CVV to prove possession, but may also require bank-issued OTP or phone call verification as well. The Secure Enclave is small, but supported between 8 and 16 cards, depending on hardware. As of iOS 17, the atorage is based on actual space available and can store upwards of 30 cards on an iPhone 14.
  - DaiPlusPlus 3y ago
    Ah, so that's how it works, thank you for the clarification.

DaiPlusPlus 3y ago

The iPhone transfers card details to Apple Watch automatically, so no, that data is not stored in a non-exportable fashion. The data-storage capacity of things like a TPM or Apple's secure enclave is absolutely tiny (e.g. the TPM specification[1] only requires ~7KiB) - which makes sense considering it only needs to store a handful of encryption keys and other stored-secrets. [1]https://trustedcomputinggroup.org/resource/pc-client-platform-tpm-profile-ptp-specification/ https://trustedcomputinggroup.org/resource/pc-client-platfor...

iancarroll 3y ago
Payment cards aren’t transferred to Apple Watch automatically. The enrollment process occurs again and the watch receives its own unique card number. The iPhone does allow you to initiate the enrollment for your Apple Watch without entering the card number again, you just need to re-enter the CVV.
rendx 3y ago
The actual TPM storage may be tiny, but you can use it to encrypt and decrypt arbitrary amounts of data. All the TPM needs to hold is the key. That you can actively ask it to transfer data to the Watch or Cloud doesn't automatically mean that it is not using the TPM for storing that data at rest, requiring the phone to be unlocked for any such transfer.
eightyfive 3y ago
Cards on an Apple Watch are provisioned separately from those on a paired phone. They have different card numbers, and are provisioned as two separate passes, each with its own fraud control. Once a pass has been added to one Apple device, a reference token to that physical card is added to your iCloud account, which can be used to initiate the provisioning flow on other devices. Usually that token requires at least a CVV to prove possession, but may also require bank-issued OTP or phone call verification as well. The Secure Enclave is small, but supported between 8 and 16 cards, depending on hardware. As of iOS 17, the atorage is based on actual space available and can store upwards of 30 cards on an iPhone 14.
- DaiPlusPlus 3y ago
  Ah, so that's how it works, thank you for the clarification.