iCloud secures your information by encrypting it when it's in transit, storing it in iCloud in an encrypted format, and using secure tokens for authentication. For certain sensitive information, Apple uses end-to-end encryption. This means that only you can access your information, and only on devices where you’re signed into iCloud. No one else, not even Apple, can access end-to-end encrypted information.
End-to-end encryption requires that you have two-factor authentication turned on for your Apple ID. Keeping your software up-to-date and using two-factor authentication are the most important things that you can do to maintain the security of your devices and data.
Here's more detail on how iCloud protects your data.
|In transit||On server|
|Backup||Yes||Yes||A minimum of 128-bit AES encryption|
|Find My Friends||Yes||Yes|
|Find My iPhone||Yes||Yes|
|Messages in iCloud||Yes||Yes|
|iCloud.com||Yes||N/A||All sessions at iCloud.com are encrypted with TLS 1.2. Any data accessed via iCloud.com is encrypted on server as indicated in this table.|
|Back to My Mac||Yes||N/A||Back to My Mac does not store data on iCloud. Data retrieved from other computers is encrypted with TLS 1.2 while in transit.|
All traffic between your devices and iCloud Mail is encrypted with TLS 1.2. Consistent with standard industry practice, iCloud does not encrypt data stored on IMAP mail servers. All Apple email clients support optional S/MIME encryption.
End-to-end encrypted data
End-to-end encryption provides the highest level of data security. Your data is protected with a key derived from information unique to your device, combined with your device passcode, which only you know. No one else can access or read this data.
These features and their data are transmitted and stored in iCloud using end-to-end encryption:
- Home data
- Health data (requires iOS 12 or later)
- iCloud Keychain (includes all of your saved accounts and passwords)
- Payment information
- Quicktype Keyboard learned vocabulary (requires iOS 11 or later)
- Screen Time
- Siri information
- Wi-Fi network information
To access your data on a new device, you might have to enter the passcode for an existing or former device.
Messages in iCloud also uses end-to-end encryption. If you have iCloud Backup turned on, your backup includes a copy of the key protecting your Messages. This ensures you can recover your Messages if you lose access to iCloud Keychain and your trusted devices. When you turn off iCloud Backup, a new key is generated on your device to protect future messages and isn't stored by Apple.
With two-factor authentication, your account can only be accessed on devices you trust, like your iPhone, iPad, or Mac. When you want to sign in with your Apple ID on a new device the first time, you need to provide two pieces of information — your password and the six-digit verification code that's auto-displayed on your trusted devices.
Use of secure tokens for authentication
When you access iCloud services with Apple’s built-in apps (for example, Mail, Contacts, and Calendar apps on iOS or macOS), authentication is handled using a secure token. Secure tokens eliminate the need to store your iCloud password on devices and computers.
End-to-end encryption for Health data requires iOS 12 and two-factor authentication. Otherwise, your data is still encrypted in storage and transmission but is not encrypted end-to-end. After you turn on two-factor authentication and update to iOS 12, your Health data is migrated to end-to-end encryption.
If you back up your device using iTunes or iCloud backups, Health data is stored only if the backup is encrypted.
Learn more about advanced security features in the iOS Security Guide.