Colour trading APK and download: check what the file is
A colour trading download may not be an app file at all. See how the first bytes of a file give it away, with a worked example.
A download labelled colour trading may be an app file, a web page, a shortcut or a copy of something else. This site hosts no files and cannot say which you have. The checker looks at the file on your own phone: it works out the fingerprint, compares it with the printed one and warns when a file does not begin like an app.
In the example, color-trading-example.apk looks like an app file by its name, but it begins with 3c 68 74 6d, the start of a web page, not the ZIP marker an Android app file has. The checker adds a warning even though the fingerprint matches the value printed for it.
A match shows the file is unchanged, not that the publisher or the app is fine. Check where the file came from too.
Common questions
Can a colour trading download be something other than an app?
Yes. It can be a saved web page, a shortcut, a document or a copy of another app. An Android app file is a ZIP archive and starts with a fixed marker, so a file that does not begin that way is not packed like an app.
What is the marker at the start of an app file?
An Android app file is a ZIP archive, and every ZIP starts with the bytes 50 4b 03 04. The checker reads those four bytes on your phone and warns when a file begins with something else, such as the start of a web page.
What do I do with a file that came without a fingerprint?
Treat it as unchecked. You can work out its fingerprint, but there is nothing to hold it against. Ask the publisher for a SHA-256 value, find another route such as a web page, or leave the file alone.
Does the file I choose leave my phone?
No. Your browser reads the file on your own device and works out the fingerprint there. Nothing is sent to this site or anywhere else, and nothing is stored.
What does a matching fingerprint prove?
Only that your file is identical to the one the fingerprint was printed for. It says nothing about who made it, what the app does once it runs, or whether it is the newest version.