6 ms·

They don't have the SEP key (that is generated in and never leaves the Secure Enclave) which it's presumably encrypted with.

bluejekyll 9y ago
When the data is in transit between devices, what encryption is being used? I mean I could speculate a manner in which it’s possible to restrict this between two devices and their respective secure enclaves, but is Apple doing that? This would mean that when backed up in Apple’s servers l, they’d have to backup per device... maybe they do?
- karlshea 9y ago
  They do all sorts of device key exchange, if you haven't watched the talk at Black Hat I'd highly recommend it: https://youtu.be/BLGFriOKz6U?t=6m55s https://youtu.be/BLGFriOKz6U?t=6m55s (link goes to beginning of Secure Enclave content, and later on in the talk he discusses iCloud which uses the SEP keys)
  - bluejekyll 9y ago
    Excellent. I’ll take a look at that, thanks for the post.
- abalone 9y ago
  The white paper goes into some detail on the encryption and key exchange mechanisms. Basically devices exchange public keys so their private keys never have to (and physically can’t) leave the SEP. Backups are different. Those are not encrypted with device keys because obviously you want to recover from loss of device and restore to a brand new one. But if you’re not comfortable with that, you can do local encrypted backups with your own password via iTunes. And as noted the most sensitive data like HealthKit is only included in encrypted backups. White paper also discusses a special escrow service for backing up your keychain, incidentally.
  - karlshea 9y ago
    > White paper also discusses a special escrow service for backing up your keychain, incidentally. My foggy understanding is that iCloud backups are encrypted with a key stored in iCloud Keychain, which is encrypted within the hardware security module escrow service they run, so after iOS 10 they can't actually decrypt your backup. Edit: oh, I replied to you below as well. That video has the details but it's been awhile since I watched it.
    - comstock 9y ago
      This contradicts statements made by Apple, most information in iCloud backups is not encrypted end-to-end. https://support.apple.com/en-us/HT202303 https://support.apple.com/en-us/HT202303
      - karlshea 9y ago
        See the iOS Security Guide page 55: https://www.apple.com/business/docs/iOS_Security_Guide.pdf https://www.apple.com/business/docs/iOS_Security_Guide.pdf It sounds like (although I'm not an expert) that it would still be impossible for them to encrypt files in higher data protection classes, since the iCloud backup keys are stored within iCloud Keychain, which is end-to-end encrypted. Edit: and honestly if I'm misinterpreting that and it's an issue for a specific person, they should just use iTunes encrypted backups and not rely on iCloud.
        comstock 9y ago
        The statements only refer to: “When files are created in Data Protection classes that aren’t accessible when the device is locked” So not photos, most data.
comstock 9y ago
iCloud backups can be decrypted by Apple, because they have the key the data is encrypted with serverside. Are you saying this data is different?
- karmelapple 9y ago
  Yes. The Secure Enclave stores the data like a fingerprint, and that data - to the best of my knowledge - is not backed up to the cloud.
  - comstock 9y ago
    Right, but we’re talking about medical data. Which in lieu of further information I assume would be backed up in the same way as iCloud data. Unless there are statements to the contrary?
  - StevenRayOrr 9y ago
    "Health data can be stored in iCloud. When configured for iCloud storage, Health data is synced between devices and secured by encryption that protects the data both in transit and at rest. Health data is only included in encrypted iTunes Backups. It is not included in either unencrypted iTunes backups or iCloud Backup." https://www.apple.com/business/docs/iOS_Security_Guide.pdf https://www.apple.com/business/docs/iOS_Security_Guide.pdf -- pg. 29 under the Health Data subsection. Edit: @bobwaycott points out the significance of this quote in the below child comment.
    - bobwaycott 9y ago
      > Health data is only included in encrypted iTunes Backups. It is not included in either unencrypted iTunes backups or iCloud Backup. Unless I’m misunderstanding you, your quote disagrees with your assertion. Health data is only included in encrypted iTunes backups. It is not included in unencrypted iTunes backups or in iCloud backups. Of course, that’s just backups. It does say it can be configured to be stored and synced between devices via iCloud, where it is encrypted in transit and at rest. That appears to indicate it is stored pre-encrypted, and does not indicate there is any way to access it outside ones devices.

bluejekyll 9y ago

When the data is in transit between devices, what encryption is being used? I mean I could speculate a manner in which it’s possible to restrict this between two devices and their respective secure enclaves, but is Apple doing that? This would mean that when backed up in Apple’s servers l, they’d have to backup per device... maybe they do?

karlshea 9y ago
They do all sorts of device key exchange, if you haven't watched the talk at Black Hat I'd highly recommend it: https://youtu.be/BLGFriOKz6U?t=6m55s https://youtu.be/BLGFriOKz6U?t=6m55s (link goes to beginning of Secure Enclave content, and later on in the talk he discusses iCloud which uses the SEP keys)
- bluejekyll 9y ago
  Excellent. I’ll take a look at that, thanks for the post.
abalone 9y ago
The white paper goes into some detail on the encryption and key exchange mechanisms. Basically devices exchange public keys so their private keys never have to (and physically can’t) leave the SEP. Backups are different. Those are not encrypted with device keys because obviously you want to recover from loss of device and restore to a brand new one. But if you’re not comfortable with that, you can do local encrypted backups with your own password via iTunes. And as noted the most sensitive data like HealthKit is only included in encrypted backups. White paper also discusses a special escrow service for backing up your keychain, incidentally.
- karlshea 9y ago
  > White paper also discusses a special escrow service for backing up your keychain, incidentally. My foggy understanding is that iCloud backups are encrypted with a key stored in iCloud Keychain, which is encrypted within the hardware security module escrow service they run, so after iOS 10 they can't actually decrypt your backup. Edit: oh, I replied to you below as well. That video has the details but it's been awhile since I watched it.
  - comstock 9y ago
    This contradicts statements made by Apple, most information in iCloud backups is not encrypted end-to-end. https://support.apple.com/en-us/HT202303 https://support.apple.com/en-us/HT202303
    - karlshea 9y ago
      See the iOS Security Guide page 55: https://www.apple.com/business/docs/iOS_Security_Guide.pdf https://www.apple.com/business/docs/iOS_Security_Guide.pdf It sounds like (although I'm not an expert) that it would still be impossible for them to encrypt files in higher data protection classes, since the iCloud backup keys are stored within iCloud Keychain, which is end-to-end encrypted. Edit: and honestly if I'm misinterpreting that and it's an issue for a specific person, they should just use iTunes encrypted backups and not rely on iCloud.
      - comstock 9y ago
        The statements only refer to: “When files are created in Data Protection classes that aren’t accessible when the device is locked” So not photos, most data.

comstock 9y ago

iCloud backups can be decrypted by Apple, because they have the key the data is encrypted with serverside. Are you saying this data is different?

karmelapple 9y ago
Yes. The Secure Enclave stores the data like a fingerprint, and that data - to the best of my knowledge - is not backed up to the cloud.
- comstock 9y ago
  Right, but we’re talking about medical data. Which in lieu of further information I assume would be backed up in the same way as iCloud data. Unless there are statements to the contrary?
- StevenRayOrr 9y ago
  "Health data can be stored in iCloud. When configured for iCloud storage, Health data is synced between devices and secured by encryption that protects the data both in transit and at rest. Health data is only included in encrypted iTunes Backups. It is not included in either unencrypted iTunes backups or iCloud Backup." https://www.apple.com/business/docs/iOS_Security_Guide.pdf https://www.apple.com/business/docs/iOS_Security_Guide.pdf -- pg. 29 under the Health Data subsection. Edit: @bobwaycott points out the significance of this quote in the below child comment.
  - bobwaycott 9y ago
    > Health data is only included in encrypted iTunes Backups. It is not included in either unencrypted iTunes backups or iCloud Backup. Unless I’m misunderstanding you, your quote disagrees with your assertion. Health data is only included in encrypted iTunes backups. It is not included in unencrypted iTunes backups or in iCloud backups. Of course, that’s just backups. It does say it can be configured to be stored and synced between devices via iCloud, where it is encrypted in transit and at rest. That appears to indicate it is stored pre-encrypted, and does not indicate there is any way to access it outside ones devices.