Fig. 4

Snapshots of the Debian keyring evolution at different points in time, showing signature age: blue, ≤1 year; green, between 1 and 2 years; yellow, between 2 and 3 years; orange, between 3 and 4 years; red, ≥4 years. Signature coloring is relative to each of the snapshots: blue edges in a represent signatures made throughout 2008. a January 2009 b January 2010 c January 2011 d January 2012 e January 2014 f December 2014 g January 2015