Incremental browser-based device fingerprinting

1. A method for incrementally fingerprinting a computing device, comprising:

(a) executing from a website, responsive to the website receiving a resource request through a web browser of a computing device, device-identification code for identifying the computing device, the device-identification code programmed to retrieve a complete set of device configuration metrics from the web browser;

(b) interrupting execution of the device-identification code after retrieval of a first subset of the device configuration metrics;

(c) generating a partial device fingerprint from the first subset of device configuration metrics;

(d) generating a temporary device identifier from the partial device fingerprint;

(e) generating a subset indicator identifying the device configuration metrics that compose the first subset;

(f) writing the temporary device identifier and the subset indicator to browser-based storage of the computing device;

(g) resuming execution of the device-identification code;

(h) querying the browser-based storage for presence of the temporary device identifier; and

(i) retrieving, responsive to detecting the temporary device identifier, a second subset of the device configuration metrics, the second subset comprising device configuration metrics not identified by the subset indicator.

2. The method of claim 1 further comprising storing the partial device fingerprint and the subset indicator in a fingerprint database.

3. The method of claim 2 further comprising updating the partial device fingerprint responsive to retrieving the second subset of the device configuration metrics.

4. The method of claim 1 wherein the interrupting of execution of the device-identification code occurs as a result of one of (i) the web browser exiting the web page, (ii) the first subset satisfying a predetermined fingerprinting criteria, and (iii) expiration of an allotted execution time.

5. The method of claim 1 wherein the resuming of execution of the device-identification code occurs as a result of one of (i) the web browser revisiting the web page, (ii) the web page fulfilling the resource request, and (iii) the web page reaching a predetermined stage in its rendering sequence.

6. The method of claim 1 further comprising, upon resuming execution of the device-identification code,

(a) querying the browser-based storage for the subset indicator, and if the subset indicator indicates that all device configuration metrics in the set have been retrieved:

(b) omitting further retrieving steps; and

(c) promoting the temporary device identifier to a permanent device identifier by (i) marking the subset indicator as permanent in the browser-based storage, and (ii) writing the temporary device identifier to device-based storage on the computing device.

7. The method of claim 6 wherein device-based storage comprises storage reserved for a Flash cookie.

8. The method of claim 1 wherein browser-based storage comprises one of DOM storage and HTML 5 storage.

9. The method of claim 1 wherein the partial device fingerprint is generated by a hashing algorithm operating on data that represents a combination of the retrieved device configuration metrics.

10. The method of claim 1 wherein the first subset consists of device configuration metrics from the complete set of device configuration metrics that:

(a) are retrievable from the web browser within a time period specified by the website; and

(b) provide highest probability among all subsets satisfying condition (i) of uniquely identifying the computing device.