Decryption using the Counter (CTR) mode.
Gwenda (PNG version), <a href="//commons.wikimedia.org/wiki/User:WhiteTimberwolf" title="User:WhiteTimberwolf">WhiteTimberwolf</a> (SVG version)
<a href="//commons.wikimedia.org/wiki/File:Ctr_decryption.png" title="File:Ctr decryption.png">PNG version</a>