Select a logo for Tails

Originally created by Tails on #5797 (Redmine)

(non-blocking)

We need a logo for Tails.

Requirements:

Free licence, compatible with GPL3+.
An image with an approximate 1:1 ratio, like the onion logo.
Plus the same image along with the “Tails” word either:
* merged with the image as in the Tor logo;
* on the side of the image.
The “Tails” name must be spelled with an uppercase “T” only, and lowercase “ails”.
The image should convey the ideas behind Tails: secrecy, privacy, anonymity, mystery, simplicity (Tails is ready-to-use).
The logo has to be a bit serious, but not sad.
Until now we reuse the colors from Tor (green and purple), but this can be changed.
We cannot reuse directly the Tor or Debian logo, but evoking it is ok (use Tor colors, or evoking the Debian swirl).
The image should be suited to print on nice stickers that people want to have on their computers, and on t-shirts that people are happy to wear.
Make sure that the fonts that you use are compatible with GPL3. To be on the safe side, use fonts available in Debian main, otherwise prove their compatibility with GPL3.

We like the idea of the tail, the cat or the mask that was used by Incognito in the past. Other ideas that meet the requirements are welcome too.

Edited May 21, 2020 by import-from-Redmine

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