Is it possible to disable screen resolution tracking? -GDPR Anonymity

T_Vandermosten · November 11, 2020, 3:39am

Hey all,

I hope you’re well

I am working on the anonymisation of the tracking data (not using cookies). There are more academic papers recently showing that a combination of device/OS/resolution/session time/Ip address/browser can actually sometime allow identification of people. I would like to disable the resolution tracking, as it’s not critical to my business, and would reinforce the privacy of my users. Is there a way to do that? I couldn’t find it in the documentation I have gone through so far.

Your help would be amazing, and appreciated

Have a great day!

Thibault

Lukas · November 12, 2020, 10:02am

Hi,

To be honest, I think that of the ones you listed, screen resolution is the one that identifies users the least as a significant fraction of users just have 1920x1080 or another very popular resolution.

There is no easy way to do it, but you could write a plugin that adds custom code to the piwik.js and overwrites this function during initialisation replaces this function

github.com

matomo-org/matomo/blob/0e7530e93f0ada22024e7226badc1d94c8309f3c/js/piwik.js#L3053


/*
 * Update domain hash
 */
function updateDomainHash() {
    domainHash = hash((configCookieDomain || domainAlias) + (configCookiePath || '/')).slice(0, 4); // 4 hexits = 16 bits
}

/*
 * Browser features (plugins, resolution, cookies)
 */
function detectBrowserFeatures() {
    if (isDefined(browserFeatures.res)) {
        return browserFeatures;
    }
    var i,
        mimeType,
        pluginMap = {
            // document types
            pdf: 'application/pdf',

            // media players

with one that doesn’t return the screen resolution (or other features).

Lukas · November 17, 2020, 9:19am

Hi,

I just thought of a much simpler solution:

You can disable the “Resolution” plugin in Matomo which is responsible for recording and aggregating this data:

Just keep in mind that the data is still sent to Matomo, but it just doesn’t store it.