Lightweight iOS library for local device fingerprinting

Demo application on the App Store

Installation (CocoaPods)

# Podfile
pod 'FingerprintJS'

Note: If you've never used CocoaPods for dependency management, check out their Using CocoaPods guide that will walk you through the setup process.

Quick Start (async/await - preferred)

import FingerprintJS
 
let fingerprinter = FingerprinterFactory.getInstance()
async {
    // Get fingerprint for the current device
    let fingerprint = await fingerprinter.getFingerprint()
    
    // Do something awesome with the fingerprint
}

Quick Start (closures - backwards compatibility)

import FingerprintJS 

let fingerprinter = FingerprinterFactory.getInstance()
fingerprinter.getFingerprint { fingerprint in
    // Do something awesome with the fingerprint
}

Fingerprint vs. DeviceId

FingerprintJS provides two main methods that return different kinds of identifiers:

1. Device identifier retrieved by calling Fingerprinter::getDeviceId() that internally uses the identifierForVendor() method which returns a unique identifier for the current application (tied to the device). FingerprintJS further remembers this identifier in the keychain, making the identifier stable even between app reinstalls.

2. Fingerprinter::getFingerprint() computes a device fingerprint by gathering device information (hardware, OS, device settings, etc.) and computing a hash value from available items. The fingerprint isn't currently as stable as the Device Identifier, because the values might change between OS updates or when the user changes settings used to compute the previous value. Furthermore, the fingerprint stability can be customized by supplying the stabilityLevel option to the Configuration object.

Configuration

Fingerprinter instance can be configured through the Configuration object that provides options to select the fingerprint version, set the desired fingerprint stability level, or change the algorithm that is used to compute the individual fingerprints.

// note that this example exists only to illustrate the available options
// and that its outcome mirrors the current default configuration

let configuration = Configuration(version: .latest, stabilityLevel: .optimal, algorithm: .sha256)
let fingerprinter = FingerprinterFactory.getInstance(config)

// fingerprinter uses latest fingerprint version with OPTIMAL stability level and SHA256 algorithm

Fingerprint Stability Levels

There are three different fingerprint stability levels, as defined in FingerprintStabilityLevel enum.

• unique that indicates the use of every signal the library is able to collect. This stability level is recommended for obtaining the most accurate fingerprint.
• optimal that indicates the use of a combination of signals that don’t change and signals that might change, though not very often. This is the default stability level and it is recommended as providing the best balance between fingerprint stability and fingerprint accuracy.
• stable that indicates the use of hardware signals or signals that aren’t supposed to change at all. This stability level is recommended for obtaining the most stable fingerprint.

NOTE: The supplied stability level is only applicable in fingerprint version v3 and later, such that it is ignored if you use fingerprint versions v1 or v2.

Creating Custom Fingerprinting Function

The default hashing function which computes the fingerprint from the content data is SHA256. The Configuration object offers a way to inject a custom hashing function by specifying .custom(YourCustomFingerprintFunctionInstance) in the algorithm variable:

struct HitchhikersFunction: FingerprintFunction {
    func fingerprint(_ data: Data) -> String {
        return "42"
    }
}

let fingerprintFunction = HitchhikersFunction()
let config = Configuration(version: .latest, stabilityLevel: .optimal, algorithm: .custom(fingerprintFunction))
let fingerprinter = FingerprinterFactory.getInstance(config)

let fingerprint = await fingerprinter.getFingerprint() // returns "42"

Keep in mind that the change in the supplied hashing function will inevitably lead to the change of the output fingerprint.

License

This library is MIT licensed. Copyright FingerprintJS, Inc. 2022.