▁for ▁prefix ▁origin ▁validation ▁already ▁exist . ▁ ▁Resource ▁Cert ific ates ▁and ▁child ▁objects ▁ ▁R PK I ▁uses ▁X . 5 0 9 ▁PK I ▁certific ates ▁( R FC ▁ 5 2 8 0 ) ▁with ▁extensions ▁for ▁IP ▁addresses ▁and ▁AS ▁ident ifiers ▁( R FC ▁ 3 7 7 9 ). ▁It ▁allows ▁the ▁members ▁of ▁regional ▁Internet ▁reg ist ries , ▁known ▁as ▁local ▁Internet ▁reg ist ries ▁( LI R s ), ▁to ▁obtain ▁a ▁resource ▁certificate ▁listing ▁the ▁Internet ▁number ▁resources ▁they ▁hold . ▁This ▁offers ▁them ▁valid atable ▁proof ▁of ▁hold ership , ▁though ▁the ▁certificate ▁does ▁not ▁contain ▁identity ▁information . ▁Using ▁the ▁resource ▁certificate , ▁L IR s ▁can ▁create ▁crypt ographic ▁att est ations ▁about ▁the ▁route ▁announ c ements ▁they ▁author ise ▁to ▁be ▁made ▁with ▁the ▁prefix es ▁they ▁hold . ▁These ▁att est ations , ▁called ▁Route ▁Orig ination ▁Author izations ▁( RO As ), ▁are ▁described ▁below . ▁ ▁Route ▁Orig ination ▁Author izations ▁ ▁A ▁Route ▁Orig ination ▁Author ization ▁states ▁which ▁autonom ous ▁system ▁( AS ) ▁is ▁author ised ▁to ▁origin ate ▁certain ▁IP ▁prefix es . ▁In ▁addition , ▁it ▁can ▁determine ▁the ▁maximum ▁length ▁of ▁the ▁prefix ▁that ▁the ▁AS ▁is ▁author ised ▁to ▁advert ise . ▁ ▁Max imum ▁prefix ▁length ▁ ▁The ▁maximum ▁prefix ▁length ▁is ▁an ▁optional ▁field . ▁When ▁not ▁defined , ▁the ▁AS ▁is ▁only ▁author ised ▁to ▁advert ise ▁exactly ▁the ▁prefix ▁specified . ▁Any ▁more