NetHash

This app is designed to enable the user to test if data files are being sent correctly to their device.

Quantitatively, this is done by computing and comparing file size and SHA-256 checksum. Qualitatively, the user can visually compare images between the original and whatever non-original version is sent by their mobile ISP.

Test your connection by selecting one or more files to test and tapping the test button.

Tap on a test to see its details, or long-press to view it (if it is an image).

You can also add your own tests. To create a new test, the app needs to detect the correct checksum and size of the file, and therefore must be run over a trusted WiFi network, or, by using HTTPS, or by creating and scanning a QR code from the NetHash Applet (http://dermochel1.dermochelys.com/html/NetHashApplet.html)

If you create a test via QR code while connected to WiFi, the app will automatically retrieve the file data, for later viewing. If you create the test while you are connected to a mobile network, you can later connect to WiFi and retrieve the file data by using the menu option when viewing test details.

Tap on a test result to see its details, including the effective transfer rate.

Long-press a test result to to view it (if it is an image) or to compare it to the original. You can also share one or more results to share, by means of either a brief text summary, or a detailed comma-separated values (CSV) file.

Lastly, you can quickly and easily see some details about your phone and network connection, including APN (for GSM mobile networks), and MCC+MNC (country and carrier code) via the Phone Info menu option.

This app was created after the author discovered in late 2011 that a US mobile provider had begun mandatory compression of most JPEG (and some PNG and GIF) images sent over their network via HTTP.

The practice remains murky, in the author's opinion, with only one provider openly providing information on the internet, while others leave vague references to the possibility in their Terms and Conditions, if they even acknowledge the possibility at all. Even calling technical support does not provide any information regarding this practice.

The author believes that this practice should see more disclosure outside of the Terms and Conditions, and that it should be able to be disabled at the user's request. This app is a step towards empowering users to know exactly what they are getting when they purchase mobile internet service.

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The author would like to extend special thanks and credit to Caribbean artist Tracey Chan for kindly allowing the use of some of her photos in this app.