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Re: [ambient-light] Security and Privacy considerations for ALS

From: Alexander Shalamov via GitHub <sysbot+gh@w3.org>
Date: Tue, 02 May 2017 13:13:30 +0000
To: public-device-apis-log@w3.org
Message-ID: <issue_comment.created-298631563-1493730809-sysbot+gh@w3.org>
@lknik We are investigating different mitigation strategies for AmbientLightSensor. Could you provide details of the setup you've used, so that everyone can reproduce the results? Would be nice to know:
- type of device
- lighting conditions
- distance to walls / ceiling or nearby objects that reflect / absorb ambient or screen light

One of the solutions is to round-up readings. We could use simple JS wrapper, to find 'safe rounding zone' for ALS readings.

```
class RoundedAmbientLightSensor {
  constructor(frequency, threshold) {
    this.onchange_ = null;
    this.illuminance_ = null;
    this.sensor_ = new AmbientLightSensor({ frequency });
    this.sensor_.onchange = () => {
      let old_illuminance = this.illuminance_;
      if (this.sensor_.illuminance != null)
        this.illuminance_  = Math.ceil(this.sensor_.illuminance / threshold) * threshold;
      if (this.onchange_ != null 
          && this.illuminance_ != null
          && old_illuminance != this.illuminance_) {
        this.onchange_();
      }
    };
  }

  set onchange(func) {
    this.onchange_ = func;
  }

  get onchange() {
    return this.onchange_;
  }

  get illuminance() {
    return this.illuminance_;
  }

  get timestamp() {
    return this.sensor_.timestamp;
  }

  start() {
    this.sensor_.start();
  }

  stop() {
    this.sensor_.stop();
  }
}
```
Example of how to use wrapper:

```
let x = new RoundedAmbientLightSensor(20, 20);
x.onchange = () => { console.log(x.illuminance); }
x.start();
```

Would you have time to re-run tests that you mentioned in your [blog post](https://blog.lukaszolejnik.com/stealing-sensitive-browser-data-with-the-w3c-ambient-light-sensor-api/)? For example, with different thresholds (5, 10, 20, 50)?

-- 
GitHub Notification of comment by alexshalamov
Please view or discuss this issue at https://github.com/w3c/ambient-light/issues/13#issuecomment-298631563 using your GitHub account
Received on Tuesday, 2 May 2017 13:13:36 UTC

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