iOS provides built-in support for file-level encryption through the Data Protection API. By enabling Data Protection, you ensure that files are encrypted automatically when the device is locked.

Enabling Data Protection

To use Data Protection, your app must be configured to support it. This is done by setting the appropriate file protection level when saving files:

Understanding File Protection Levels

iOS offers several file protection levels, each with different security guarantees:

• .completeFileProtection: Files are encrypted and inaccessible when the device is locked.
• .completeUntilFirstUserAuthentication: Files are encrypted until the device is unlocked for the first time after a restart.
• .completeUnlessOpen: Files are encrypted unless they are open when the device is locked.

The Keychain is a secure storage service provided by iOS for storing small amounts of sensitive data, such as passwords, encryption keys, and certificates. Data stored in the Keychain is encrypted and can only be accessed by your app.

Using the Keychain

Storing data in the Keychain is straightforward, but requires careful management to avoid issues such as data loss or unauthorized access. Here’s how you can securely store a password:

In this example, savePassword securely stores a password in the Keychain, and getPassword retrieves it when needed.

For scenarios where you prefer to use high-level APIs for cryptographic operations, Swift's native Security framework is an excellent choice. Below is an example of securely encrypting and decrypting data using the Security framework:

Encrypting Data

The following example demonstrates how to encrypt data using a public key. This is commonly used for scenarios such as securely transmitting data:

Decrypting Data

To decrypt data, you would use the private key corresponding to the public key. Below is an example:

Another important aspect of data protection is ensuring that sensitive user input is handled securely and that data isn't inadvertently exposed through the clipboard or screenshots.

Securing Text Input

When dealing with sensitive information, such as passwords or personal data, it's important to use secure text input fields. For instance, setting the isSecureTextEntry property on a UITextField ensures that the input is not displayed as plain text:

This simple step prevents sensitive information from being exposed on the screen.

Protecting Clipboard Data

The iOS clipboard is shared across all apps, which means that any data copied to the clipboard can potentially be accessed by other apps. To protect sensitive data, avoid copying it to the clipboard. If you must use the clipboard, consider clearing it immediately after use:

Preventing Screenshots

To prevent sensitive information from being captured in screenshots or recorded by screen recording, you can use the isScreenCaptured property and handle it accordingly. Additionally, you can obscure sensitive data when the app is backgrounded:

This technique places an overlay on top of your app's UI or apply a blur effect to the entire view to any sensitive content when the app is sent to the background.