Editing Weak key (section)

In [[cryptography]], a '''weak key''' is a [[key (cryptography)|key]], which, used with a specific [[cipher]], makes the cipher behave in some undesirable way. Weak keys usually represent a very small fraction of the overall keyspace, which usually means that, a cipher key made by [[random number generation]] is very unlikely to give rise to a security problem.  Nevertheless, it is considered desirable for a cipher to have no weak keys.  A cipher with no weak keys is said to have a ''flat'', or ''linear'',  [[key space (cryptography)|key space]].