@startuml
skinparam monochrome true
skinparam defaultFontName Arial
skinparam classFontSize 10
skinparam sequenceBoxBorderColor #black
participant "**Accessor Authentication Service gate**" as aas 
participant "**Accessor Authentication Application gate**" as aaa 
autonumber
 ...
aaa->aas: AAS-OP-GET-CHALLENGE-Service-Command
aas-->aaa: eAAS-OK, aChallenge 
...
aaa->aas: AAS-OP-AUTHENTICATE-ACCESSOR-Service-Command (Certification_Path<sub>ATK_AAA</sub>)
aas-->aaa: eAAS-OK, (Certification_Path<sub>ATK.AAS</sub>)
@enduml