Editing Scytale (section)

==Message authentication hypothesis==
An alternative hypothesis is that the scytale was used for message authentication rather than encryption.<ref name=Russel99>{{cite book|last=Russel|first=Frank|title=Information Gathering in Classical Greece|year=1999|publisher=U. Michigan Press|pages=117|isbn=0-472-11064-0}}</ref>  Only if the sender wrote the message around a scytale of the same diameter as the receiver's would the receiver be able to read it.  It would therefore be difficult for enemy spies to inject false messages into the communication between two commanders.

Nonetheless, any person intercepting a scytale message, and having heard about the method, could with little difficulty find out the rod size needed (a kind of [[brute-force attack]]); once knowing that, it would be easy to supplant the sender and forge new messages.