File:128px-Padlock-black.svg.png

A black padlock icon

This apparently was created by AJ Ashton

It was imported wikimedia commons via the Open Clipart Library, where it was released explicitly into the public domain, using the Creative Commons CC0 1.0 Universal Public Domain Dedication. ...At this URL which no longer works: http://openclipart.org/clipart//signs_and_symbols/padlock_aj_ashton_01.svg

See wikimedia commons info: http://commons.wikimedia.org/wiki/File:Padlock-black.svg (And SVG vector file)